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-rw-r--r--nixos/modules/services/backup/automysqlbackup.nix119
-rw-r--r--nixos/modules/services/backup/bacula.nix578
-rw-r--r--nixos/modules/services/backup/borgbackup.nix730
-rw-r--r--nixos/modules/services/backup/borgbackup.xml209
-rw-r--r--nixos/modules/services/backup/borgmatic.nix57
-rw-r--r--nixos/modules/services/backup/btrbk.nix220
-rw-r--r--nixos/modules/services/backup/duplicati.nix86
-rw-r--r--nixos/modules/services/backup/duplicity.nix196
-rw-r--r--nixos/modules/services/backup/mysql-backup.nix130
-rw-r--r--nixos/modules/services/backup/postgresql-backup.nix164
-rw-r--r--nixos/modules/services/backup/postgresql-wal-receiver.nix204
-rw-r--r--nixos/modules/services/backup/restic-rest-server.nix111
-rw-r--r--nixos/modules/services/backup/restic.nix290
-rw-r--r--nixos/modules/services/backup/rsnapshot.nix75
-rw-r--r--nixos/modules/services/backup/sanoid.nix204
-rw-r--r--nixos/modules/services/backup/syncoid.nix421
-rw-r--r--nixos/modules/services/backup/tarsnap.nix408
-rw-r--r--nixos/modules/services/backup/tsm.nix125
-rw-r--r--nixos/modules/services/backup/zfs-replication.nix90
-rw-r--r--nixos/modules/services/backup/znapzend.nix469
-rw-r--r--nixos/modules/services/backup/zrepl.nix54
21 files changed, 4940 insertions, 0 deletions
diff --git a/nixos/modules/services/backup/automysqlbackup.nix b/nixos/modules/services/backup/automysqlbackup.nix
new file mode 100644
index 00000000000..fd2764a40ad
--- /dev/null
+++ b/nixos/modules/services/backup/automysqlbackup.nix
@@ -0,0 +1,119 @@
+{ config, lib, pkgs, ... }:
+
+let
+
+  inherit (lib) concatMapStringsSep concatStringsSep isInt isList literalExpression;
+  inherit (lib) mapAttrs mapAttrsToList mkDefault mkEnableOption mkIf mkOption optional types;
+
+  cfg = config.services.automysqlbackup;
+  pkg = pkgs.automysqlbackup;
+  user = "automysqlbackup";
+  group = "automysqlbackup";
+
+  toStr = val:
+    if isList val then "( ${concatMapStringsSep " " (val: "'${val}'") val} )"
+    else if isInt val then toString val
+    else if true == val then "'yes'"
+    else if false == val then "'no'"
+    else "'${toString val}'";
+
+  configFile = pkgs.writeText "automysqlbackup.conf" ''
+    #version=${pkg.version}
+    # DONT'T REMOVE THE PREVIOUS VERSION LINE!
+    #
+    ${concatStringsSep "\n" (mapAttrsToList (name: value: "CONFIG_${name}=${toStr value}") cfg.config)}
+  '';
+
+in
+{
+  # interface
+  options = {
+    services.automysqlbackup = {
+
+      enable = mkEnableOption "AutoMySQLBackup";
+
+      calendar = mkOption {
+        type = types.str;
+        default = "01:15:00";
+        description = ''
+          Configured when to run the backup service systemd unit (DayOfWeek Year-Month-Day Hour:Minute:Second).
+        '';
+      };
+
+      config = mkOption {
+        type = with types; attrsOf (oneOf [ str int bool (listOf str) ]);
+        default = {};
+        description = ''
+          automysqlbackup configuration. Refer to
+          <filename>''${pkgs.automysqlbackup}/etc/automysqlbackup.conf</filename>
+          for details on supported values.
+        '';
+        example = literalExpression ''
+          {
+            db_names = [ "nextcloud" "matomo" ];
+            table_exclude = [ "nextcloud.oc_users" "nextcloud.oc_whats_new" ];
+            mailcontent = "log";
+            mail_address = "admin@example.org";
+          }
+        '';
+      };
+
+    };
+  };
+
+  # implementation
+  config = mkIf cfg.enable {
+
+    assertions = [
+      { assertion = !config.services.mysqlBackup.enable;
+        message = "Please choose one of services.mysqlBackup or services.automysqlbackup.";
+      }
+    ];
+
+    services.automysqlbackup.config = mapAttrs (name: mkDefault) {
+      mysql_dump_username = user;
+      mysql_dump_host = "localhost";
+      mysql_dump_socket = "/run/mysqld/mysqld.sock";
+      backup_dir = "/var/backup/mysql";
+      db_exclude = [ "information_schema" "performance_schema" ];
+      mailcontent = "stdout";
+      mysql_dump_single_transaction = true;
+    };
+
+    systemd.timers.automysqlbackup = {
+      description = "automysqlbackup timer";
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        OnCalendar = cfg.calendar;
+        AccuracySec = "5m";
+      };
+    };
+
+    systemd.services.automysqlbackup = {
+      description = "automysqlbackup service";
+      serviceConfig = {
+        User = user;
+        Group = group;
+        ExecStart = "${pkg}/bin/automysqlbackup ${configFile}";
+      };
+    };
+
+    environment.systemPackages = [ pkg ];
+
+    users.users.${user} = {
+      group = group;
+      isSystemUser = true;
+    };
+    users.groups.${group} = { };
+
+    systemd.tmpfiles.rules = [
+      "d '${cfg.config.backup_dir}' 0750 ${user} ${group} - -"
+    ];
+
+    services.mysql.ensureUsers = optional (config.services.mysql.enable && cfg.config.mysql_dump_host == "localhost") {
+      name = user;
+      ensurePermissions = { "*.*" = "SELECT, SHOW VIEW, TRIGGER, LOCK TABLES"; };
+    };
+
+  };
+}
diff --git a/nixos/modules/services/backup/bacula.nix b/nixos/modules/services/backup/bacula.nix
new file mode 100644
index 00000000000..59890204234
--- /dev/null
+++ b/nixos/modules/services/backup/bacula.nix
@@ -0,0 +1,578 @@
+{ config, lib, pkgs, ... }:
+
+
+# TODO: test configuration when building nixexpr (use -t parameter)
+# TODO: support sqlite3 (it's deprecate?) and mysql
+
+with lib;
+
+let
+  libDir = "/var/lib/bacula";
+
+  fd_cfg = config.services.bacula-fd;
+  fd_conf = pkgs.writeText "bacula-fd.conf"
+    ''
+      Client {
+        Name = "${fd_cfg.name}";
+        FDPort = ${toString fd_cfg.port};
+        WorkingDirectory = "${libDir}";
+        Pid Directory = "/run";
+        ${fd_cfg.extraClientConfig}
+      }
+
+      ${concatStringsSep "\n" (mapAttrsToList (name: value: ''
+      Director {
+        Name = "${name}";
+        Password = "${value.password}";
+        Monitor = "${value.monitor}";
+      }
+      '') fd_cfg.director)}
+
+      Messages {
+        Name = Standard;
+        syslog = all, !skipped, !restored
+        ${fd_cfg.extraMessagesConfig}
+      }
+    '';
+
+  sd_cfg = config.services.bacula-sd;
+  sd_conf = pkgs.writeText "bacula-sd.conf"
+    ''
+      Storage {
+        Name = "${sd_cfg.name}";
+        SDPort = ${toString sd_cfg.port};
+        WorkingDirectory = "${libDir}";
+        Pid Directory = "/run";
+        ${sd_cfg.extraStorageConfig}
+      }
+
+      ${concatStringsSep "\n" (mapAttrsToList (name: value: ''
+      Autochanger {
+        Name = "${name}";
+        Device = ${concatStringsSep ", " (map (a: "\"${a}\"") value.devices)};
+        Changer Device =  "${value.changerDevice}";
+        Changer Command = "${value.changerCommand}";
+        ${value.extraAutochangerConfig}
+      }
+      '') sd_cfg.autochanger)}
+
+      ${concatStringsSep "\n" (mapAttrsToList (name: value: ''
+      Device {
+        Name = "${name}";
+        Archive Device = "${value.archiveDevice}";
+        Media Type = "${value.mediaType}";
+        ${value.extraDeviceConfig}
+      }
+      '') sd_cfg.device)}
+
+      ${concatStringsSep "\n" (mapAttrsToList (name: value: ''
+      Director {
+        Name = "${name}";
+        Password = "${value.password}";
+        Monitor = "${value.monitor}";
+      }
+      '') sd_cfg.director)}
+
+      Messages {
+        Name = Standard;
+        syslog = all, !skipped, !restored
+        ${sd_cfg.extraMessagesConfig}
+      }
+    '';
+
+  dir_cfg = config.services.bacula-dir;
+  dir_conf = pkgs.writeText "bacula-dir.conf"
+    ''
+    Director {
+      Name = "${dir_cfg.name}";
+      Password = "${dir_cfg.password}";
+      DirPort = ${toString dir_cfg.port};
+      Working Directory = "${libDir}";
+      Pid Directory = "/run/";
+      QueryFile = "${pkgs.bacula}/etc/query.sql";
+      ${dir_cfg.extraDirectorConfig}
+    }
+
+    Catalog {
+      Name = "PostgreSQL";
+      dbname = "bacula";
+      user = "bacula";
+    }
+
+    Messages {
+      Name = Standard;
+      syslog = all, !skipped, !restored
+      ${dir_cfg.extraMessagesConfig}
+    }
+
+    ${dir_cfg.extraConfig}
+    '';
+
+  directorOptions = {...}:
+  {
+    options = {
+      password = mkOption {
+        type = types.str;
+        # TODO: required?
+        description = ''
+          Specifies the password that must be supplied for the default Bacula
+          Console to be authorized. The same password must appear in the
+          Director resource of the Console configuration file. For added
+          security, the password is never passed across the network but instead
+          a challenge response hash code created with the password. This
+          directive is required. If you have either /dev/random or bc on your
+          machine, Bacula will generate a random password during the
+          configuration process, otherwise it will be left blank and you must
+          manually supply it.
+
+          The password is plain text. It is not generated through any special
+          process but as noted above, it is better to use random text for
+          security reasons.
+        '';
+      };
+
+      monitor = mkOption {
+        type = types.enum [ "no" "yes" ];
+        default = "no";
+        example = "yes";
+        description = ''
+          If Monitor is set to <literal>no</literal>, this director will have
+          full access to this Storage daemon. If Monitor is set to
+          <literal>yes</literal>, this director will only be able to fetch the
+          current status of this Storage daemon.
+
+          Please note that if this director is being used by a Monitor, we
+          highly recommend to set this directive to yes to avoid serious
+          security problems.
+        '';
+      };
+    };
+  };
+
+  autochangerOptions = {...}:
+  {
+    options = {
+      changerDevice = mkOption {
+        type = types.str;
+        description = ''
+          The specified name-string must be the generic SCSI device name of the
+          autochanger that corresponds to the normal read/write Archive Device
+          specified in the Device resource. This generic SCSI device name
+          should be specified if you have an autochanger or if you have a
+          standard tape drive and want to use the Alert Command (see below).
+          For example, on Linux systems, for an Archive Device name of
+          <literal>/dev/nst0</literal>, you would specify
+          <literal>/dev/sg0</literal> for the Changer Device name.  Depending
+          on your exact configuration, and the number of autochangers or the
+          type of autochanger, what you specify here can vary. This directive
+          is optional. See the Using AutochangersAutochangersChapter chapter of
+          this manual for more details of using this and the following
+          autochanger directives.
+          '';
+      };
+
+      changerCommand = mkOption {
+        type = types.str;
+        description = ''
+          The name-string specifies an external program to be called that will
+          automatically change volumes as required by Bacula. Normally, this
+          directive will be specified only in the AutoChanger resource, which
+          is then used for all devices. However, you may also specify the
+          different Changer Command in each Device resource. Most frequently,
+          you will specify the Bacula supplied mtx-changer script as follows:
+
+          <literal>"/path/mtx-changer %c %o %S %a %d"</literal>
+
+          and you will install the mtx on your system (found in the depkgs
+          release). An example of this command is in the default bacula-sd.conf
+          file. For more details on the substitution characters that may be
+          specified to configure your autochanger please see the
+          AutochangersAutochangersChapter chapter of this manual. For FreeBSD
+          users, you might want to see one of the several chio scripts in
+          examples/autochangers.
+          '';
+        default = "/etc/bacula/mtx-changer %c %o %S %a %d";
+      };
+
+      devices = mkOption {
+        description = "";
+        type = types.listOf types.str;
+      };
+
+      extraAutochangerConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Autochanger directive.
+        '';
+        example = ''
+
+        '';
+      };
+    };
+  };
+
+
+  deviceOptions = {...}:
+  {
+    options = {
+      archiveDevice = mkOption {
+        # TODO: required?
+        type = types.str;
+        description = ''
+          The specified name-string gives the system file name of the storage
+          device managed by this storage daemon. This will usually be the
+          device file name of a removable storage device (tape drive), for
+          example <literal>/dev/nst0</literal> or
+          <literal>/dev/rmt/0mbn</literal>. For a DVD-writer, it will be for
+          example <literal>/dev/hdc</literal>. It may also be a directory name
+          if you are archiving to disk storage. In this case, you must supply
+          the full absolute path to the directory. When specifying a tape
+          device, it is preferable that the "non-rewind" variant of the device
+          file name be given.
+        '';
+      };
+
+      mediaType = mkOption {
+        # TODO: required?
+        type = types.str;
+        description = ''
+          The specified name-string names the type of media supported by this
+          device, for example, <literal>DLT7000</literal>. Media type names are
+          arbitrary in that you set them to anything you want, but they must be
+          known to the volume database to keep track of which storage daemons
+          can read which volumes. In general, each different storage type
+          should have a unique Media Type associated with it. The same
+          name-string must appear in the appropriate Storage resource
+          definition in the Director's configuration file.
+
+          Even though the names you assign are arbitrary (i.e. you choose the
+          name you want), you should take care in specifying them because the
+          Media Type is used to determine which storage device Bacula will
+          select during restore. Thus you should probably use the same Media
+          Type specification for all drives where the Media can be freely
+          interchanged. This is not generally an issue if you have a single
+          Storage daemon, but it is with multiple Storage daemons, especially
+          if they have incompatible media.
+
+          For example, if you specify a Media Type of <literal>DDS-4</literal>
+          then during the restore, Bacula will be able to choose any Storage
+          Daemon that handles <literal>DDS-4</literal>. If you have an
+          autochanger, you might want to name the Media Type in a way that is
+          unique to the autochanger, unless you wish to possibly use the
+          Volumes in other drives. You should also ensure to have unique Media
+          Type names if the Media is not compatible between drives. This
+          specification is required for all devices.
+
+          In addition, if you are using disk storage, each Device resource will
+          generally have a different mount point or directory. In order for
+          Bacula to select the correct Device resource, each one must have a
+          unique Media Type.
+        '';
+      };
+
+      extraDeviceConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Device directive.
+        '';
+        example = ''
+          LabelMedia = yes
+          Random Access = no
+          AutomaticMount = no
+          RemovableMedia = no
+          MaximumOpenWait = 60
+          AlwaysOpen = no
+        '';
+      };
+    };
+  };
+
+in {
+  options = {
+    services.bacula-fd = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable the Bacula File Daemon.
+        '';
+      };
+
+      name = mkOption {
+        default = "${config.networking.hostName}-fd";
+        defaultText = literalExpression ''"''${config.networking.hostName}-fd"'';
+        type = types.str;
+        description = ''
+          The client name that must be used by the Director when connecting.
+          Generally, it is a good idea to use a name related to the machine so
+          that error messages can be easily identified if you have multiple
+          Clients. This directive is required.
+        '';
+      };
+
+      port = mkOption {
+        default = 9102;
+        type = types.int;
+        description = ''
+          This specifies the port number on which the Client listens for
+          Director connections. It must agree with the FDPort specified in
+          the Client resource of the Director's configuration file.
+        '';
+      };
+
+      director = mkOption {
+        default = {};
+        description = ''
+          This option defines director resources in Bacula File Daemon.
+        '';
+        type = with types; attrsOf (submodule directorOptions);
+      };
+
+      extraClientConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Client directive.
+        '';
+        example = ''
+          Maximum Concurrent Jobs = 20;
+          Heartbeat Interval = 30;
+        '';
+      };
+
+      extraMessagesConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Messages directive.
+        '';
+        example = ''
+          console = all
+        '';
+      };
+    };
+
+    services.bacula-sd = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable Bacula Storage Daemon.
+        '';
+      };
+
+      name = mkOption {
+        default = "${config.networking.hostName}-sd";
+        defaultText = literalExpression ''"''${config.networking.hostName}-sd"'';
+        type = types.str;
+        description = ''
+          Specifies the Name of the Storage daemon.
+        '';
+      };
+
+      port = mkOption {
+        default = 9103;
+        type = types.int;
+        description = ''
+          Specifies port number on which the Storage daemon listens for
+          Director connections.
+        '';
+      };
+
+      director = mkOption {
+        default = {};
+        description = ''
+          This option defines Director resources in Bacula Storage Daemon.
+        '';
+        type = with types; attrsOf (submodule directorOptions);
+      };
+
+      device = mkOption {
+        default = {};
+        description = ''
+          This option defines Device resources in Bacula Storage Daemon.
+        '';
+        type = with types; attrsOf (submodule deviceOptions);
+      };
+
+      autochanger = mkOption {
+        default = {};
+        description = ''
+          This option defines Autochanger resources in Bacula Storage Daemon.
+        '';
+        type = with types; attrsOf (submodule autochangerOptions);
+      };
+
+      extraStorageConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Storage directive.
+        '';
+        example = ''
+          Maximum Concurrent Jobs = 20;
+          Heartbeat Interval = 30;
+        '';
+      };
+
+      extraMessagesConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Messages directive.
+        '';
+        example = ''
+          console = all
+        '';
+      };
+
+    };
+
+    services.bacula-dir = {
+      enable = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Whether to enable Bacula Director Daemon.
+        '';
+      };
+
+      name = mkOption {
+        default = "${config.networking.hostName}-dir";
+        defaultText = literalExpression ''"''${config.networking.hostName}-dir"'';
+        type = types.str;
+        description = ''
+          The director name used by the system administrator. This directive is
+          required.
+        '';
+      };
+
+      port = mkOption {
+        default = 9101;
+        type = types.int;
+        description = ''
+          Specify the port (a positive integer) on which the Director daemon
+          will listen for Bacula Console connections. This same port number
+          must be specified in the Director resource of the Console
+          configuration file. The default is 9101, so normally this directive
+          need not be specified. This directive should not be used if you
+          specify DirAddresses (N.B plural) directive.
+        '';
+      };
+
+      password = mkOption {
+        # TODO: required?
+        type = types.str;
+        description = ''
+           Specifies the password that must be supplied for a Director.
+        '';
+      };
+
+      extraMessagesConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Messages directive.
+        '';
+        example = ''
+          console = all
+        '';
+      };
+
+      extraDirectorConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration to be passed in Director directive.
+        '';
+        example = ''
+          Maximum Concurrent Jobs = 20;
+          Heartbeat Interval = 30;
+        '';
+      };
+
+      extraConfig = mkOption {
+        default = "";
+        type = types.lines;
+        description = ''
+          Extra configuration for Bacula Director Daemon.
+        '';
+        example = ''
+          TODO
+        '';
+      };
+    };
+  };
+
+  config = mkIf (fd_cfg.enable || sd_cfg.enable || dir_cfg.enable) {
+    systemd.services.bacula-fd = mkIf fd_cfg.enable {
+      after = [ "network.target" ];
+      description = "Bacula File Daemon";
+      wantedBy = [ "multi-user.target" ];
+      path = [ pkgs.bacula ];
+      serviceConfig = {
+        ExecStart = "${pkgs.bacula}/sbin/bacula-fd -f -u root -g bacula -c ${fd_conf}";
+        ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+        LogsDirectory = "bacula";
+        StateDirectory = "bacula";
+      };
+    };
+
+    systemd.services.bacula-sd = mkIf sd_cfg.enable {
+      after = [ "network.target" ];
+      description = "Bacula Storage Daemon";
+      wantedBy = [ "multi-user.target" ];
+      path = [ pkgs.bacula ];
+      serviceConfig = {
+        ExecStart = "${pkgs.bacula}/sbin/bacula-sd -f -u bacula -g bacula -c ${sd_conf}";
+        ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+        LogsDirectory = "bacula";
+        StateDirectory = "bacula";
+      };
+    };
+
+    services.postgresql.enable = dir_cfg.enable == true;
+
+    systemd.services.bacula-dir = mkIf dir_cfg.enable {
+      after = [ "network.target" "postgresql.service" ];
+      description = "Bacula Director Daemon";
+      wantedBy = [ "multi-user.target" ];
+      path = [ pkgs.bacula ];
+      serviceConfig = {
+        ExecStart = "${pkgs.bacula}/sbin/bacula-dir -f -u bacula -g bacula -c ${dir_conf}";
+        ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+        LogsDirectory = "bacula";
+        StateDirectory = "bacula";
+      };
+      preStart = ''
+        if ! test -e "${libDir}/db-created"; then
+            ${pkgs.postgresql}/bin/createuser --no-superuser --no-createdb --no-createrole bacula
+            #${pkgs.postgresql}/bin/createdb --owner bacula bacula
+
+            # populate DB
+            ${pkgs.bacula}/etc/create_bacula_database postgresql
+            ${pkgs.bacula}/etc/make_bacula_tables postgresql
+            ${pkgs.bacula}/etc/grant_bacula_privileges postgresql
+            touch "${libDir}/db-created"
+        else
+            ${pkgs.bacula}/etc/update_bacula_tables postgresql || true
+        fi
+      '';
+    };
+
+    environment.systemPackages = [ pkgs.bacula ];
+
+    users.users.bacula = {
+      group = "bacula";
+      uid = config.ids.uids.bacula;
+      home = "${libDir}";
+      createHome = true;
+      description = "Bacula Daemons user";
+      shell = "${pkgs.bash}/bin/bash";
+    };
+
+    users.groups.bacula.gid = config.ids.gids.bacula;
+  };
+}
diff --git a/nixos/modules/services/backup/borgbackup.nix b/nixos/modules/services/backup/borgbackup.nix
new file mode 100644
index 00000000000..4c9ddfe4674
--- /dev/null
+++ b/nixos/modules/services/backup/borgbackup.nix
@@ -0,0 +1,730 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  isLocalPath = x:
+    builtins.substring 0 1 x == "/"      # absolute path
+    || builtins.substring 0 1 x == "."   # relative path
+    || builtins.match "[.*:.*]" == null; # not machine:path
+
+  mkExcludeFile = cfg:
+    # Write each exclude pattern to a new line
+    pkgs.writeText "excludefile" (concatStringsSep "\n" cfg.exclude);
+
+  mkKeepArgs = cfg:
+    # If cfg.prune.keep e.g. has a yearly attribute,
+    # its content is passed on as --keep-yearly
+    concatStringsSep " "
+      (mapAttrsToList (x: y: "--keep-${x}=${toString y}") cfg.prune.keep);
+
+  mkBackupScript = cfg: ''
+    on_exit()
+    {
+      exitStatus=$?
+      # Reset the EXIT handler, or else we're called again on 'exit' below
+      trap - EXIT
+      ${cfg.postHook}
+      exit $exitStatus
+    }
+    trap 'on_exit' INT TERM QUIT EXIT
+
+    archiveName="${if cfg.archiveBaseName == null then "" else cfg.archiveBaseName + "-"}$(date ${cfg.dateFormat})"
+    archiveSuffix="${optionalString cfg.appendFailedSuffix ".failed"}"
+    ${cfg.preHook}
+  '' + optionalString cfg.doInit ''
+    # Run borg init if the repo doesn't exist yet
+    if ! borg list $extraArgs > /dev/null; then
+      borg init $extraArgs \
+        --encryption ${cfg.encryption.mode} \
+        $extraInitArgs
+      ${cfg.postInit}
+    fi
+  '' + ''
+    (
+      set -o pipefail
+      ${optionalString (cfg.dumpCommand != null) ''${escapeShellArg cfg.dumpCommand} | \''}
+      borg create $extraArgs \
+        --compression ${cfg.compression} \
+        --exclude-from ${mkExcludeFile cfg} \
+        $extraCreateArgs \
+        "::$archiveName$archiveSuffix" \
+        ${if cfg.paths == null then "-" else escapeShellArgs cfg.paths}
+    )
+  '' + optionalString cfg.appendFailedSuffix ''
+    borg rename $extraArgs \
+      "::$archiveName$archiveSuffix" "$archiveName"
+  '' + ''
+    ${cfg.postCreate}
+  '' + optionalString (cfg.prune.keep != { }) ''
+    borg prune $extraArgs \
+      ${mkKeepArgs cfg} \
+      ${optionalString (cfg.prune.prefix != null) "--prefix ${escapeShellArg cfg.prune.prefix} \\"}
+      $extraPruneArgs
+    ${cfg.postPrune}
+  '';
+
+  mkPassEnv = cfg: with cfg.encryption;
+    if passCommand != null then
+      { BORG_PASSCOMMAND = passCommand; }
+    else if passphrase != null then
+      { BORG_PASSPHRASE = passphrase; }
+    else { };
+
+  mkBackupService = name: cfg:
+    let
+      userHome = config.users.users.${cfg.user}.home;
+    in nameValuePair "borgbackup-job-${name}" {
+      description = "BorgBackup job ${name}";
+      path = with pkgs; [
+        borgbackup openssh
+      ];
+      script = mkBackupScript cfg;
+      serviceConfig = {
+        User = cfg.user;
+        Group = cfg.group;
+        # Only run when no other process is using CPU or disk
+        CPUSchedulingPolicy = "idle";
+        IOSchedulingClass = "idle";
+        ProtectSystem = "strict";
+        ReadWritePaths =
+          [ "${userHome}/.config/borg" "${userHome}/.cache/borg" ]
+          ++ cfg.readWritePaths
+          # Borg needs write access to repo if it is not remote
+          ++ optional (isLocalPath cfg.repo) cfg.repo;
+        PrivateTmp = cfg.privateTmp;
+      };
+      environment = {
+        BORG_REPO = cfg.repo;
+        inherit (cfg) extraArgs extraInitArgs extraCreateArgs extraPruneArgs;
+      } // (mkPassEnv cfg) // cfg.environment;
+    };
+
+  mkBackupTimers = name: cfg:
+    nameValuePair "borgbackup-job-${name}" {
+      description = "BorgBackup job ${name} timer";
+      wantedBy = [ "timers.target" ];
+      timerConfig = {
+        Persistent = cfg.persistentTimer;
+        OnCalendar = cfg.startAt;
+      };
+      # if remote-backup wait for network
+      after = optional (cfg.persistentTimer && !isLocalPath cfg.repo) "network-online.target";
+    };
+
+  # utility function around makeWrapper
+  mkWrapperDrv = {
+      original, name, set ? {}
+    }:
+    pkgs.runCommand "${name}-wrapper" {
+      buildInputs = [ pkgs.makeWrapper ];
+    } (with lib; ''
+      makeWrapper "${original}" "$out/bin/${name}" \
+        ${concatStringsSep " \\\n " (mapAttrsToList (name: value: ''--set ${name} "${value}"'') set)}
+    '');
+
+  mkBorgWrapper = name: cfg: mkWrapperDrv {
+    original = "${pkgs.borgbackup}/bin/borg";
+    name = "borg-job-${name}";
+    set = { BORG_REPO = cfg.repo; } // (mkPassEnv cfg) // cfg.environment;
+  };
+
+  # Paths listed in ReadWritePaths must exist before service is started
+  mkActivationScript = name: cfg:
+    let
+      install = "install -o ${cfg.user} -g ${cfg.group}";
+    in
+      nameValuePair "borgbackup-job-${name}" (stringAfter [ "users" ] (''
+        # Ensure that the home directory already exists
+        # We can't assert createHome == true because that's not the case for root
+        cd "${config.users.users.${cfg.user}.home}"
+        ${install} -d .config/borg
+        ${install} -d .cache/borg
+      '' + optionalString (isLocalPath cfg.repo && !cfg.removableDevice) ''
+        ${install} -d ${escapeShellArg cfg.repo}
+      ''));
+
+  mkPassAssertion = name: cfg: {
+    assertion = with cfg.encryption;
+      mode != "none" -> passCommand != null || passphrase != null;
+    message =
+      "passCommand or passphrase has to be specified because"
+      + '' borgbackup.jobs.${name}.encryption != "none"'';
+  };
+
+  mkRepoService = name: cfg:
+    nameValuePair "borgbackup-repo-${name}" {
+      description = "Create BorgBackup repository ${name} directory";
+      script = ''
+        mkdir -p ${escapeShellArg cfg.path}
+        chown ${cfg.user}:${cfg.group} ${escapeShellArg cfg.path}
+      '';
+      serviceConfig = {
+        # The service's only task is to ensure that the specified path exists
+        Type = "oneshot";
+      };
+      wantedBy = [ "multi-user.target" ];
+    };
+
+  mkAuthorizedKey = cfg: appendOnly: key:
+    let
+      # Because of the following line, clients do not need to specify an absolute repo path
+      cdCommand = "cd ${escapeShellArg cfg.path}";
+      restrictedArg = "--restrict-to-${if cfg.allowSubRepos then "path" else "repository"} .";
+      appendOnlyArg = optionalString appendOnly "--append-only";
+      quotaArg = optionalString (cfg.quota != null) "--storage-quota ${cfg.quota}";
+      serveCommand = "borg serve ${restrictedArg} ${appendOnlyArg} ${quotaArg}";
+    in
+      ''command="${cdCommand} && ${serveCommand}",restrict ${key}'';
+
+  mkUsersConfig = name: cfg: {
+    users.${cfg.user} = {
+      openssh.authorizedKeys.keys =
+        (map (mkAuthorizedKey cfg false) cfg.authorizedKeys
+        ++ map (mkAuthorizedKey cfg true) cfg.authorizedKeysAppendOnly);
+      useDefaultShell = true;
+      group = cfg.group;
+      isSystemUser = true;
+    };
+    groups.${cfg.group} = { };
+  };
+
+  mkKeysAssertion = name: cfg: {
+    assertion = cfg.authorizedKeys != [ ] || cfg.authorizedKeysAppendOnly != [ ];
+    message =
+      "borgbackup.repos.${name} does not make sense"
+      + " without at least one public key";
+  };
+
+  mkSourceAssertions = name: cfg: {
+    assertion = count isNull [ cfg.dumpCommand cfg.paths ] == 1;
+    message = ''
+      Exactly one of borgbackup.jobs.${name}.paths or borgbackup.jobs.${name}.dumpCommand
+      must be set.
+    '';
+  };
+
+  mkRemovableDeviceAssertions = name: cfg: {
+    assertion = !(isLocalPath cfg.repo) -> !cfg.removableDevice;
+    message = ''
+      borgbackup.repos.${name}: repo isn't a local path, thus it can't be a removable device!
+    '';
+  };
+
+in {
+  meta.maintainers = with maintainers; [ dotlambda ];
+  meta.doc = ./borgbackup.xml;
+
+  ###### interface
+
+  options.services.borgbackup.jobs = mkOption {
+    description = ''
+      Deduplicating backups using BorgBackup.
+      Adding a job will cause a borg-job-NAME wrapper to be added
+      to your system path, so that you can perform maintenance easily.
+      See also the chapter about BorgBackup in the NixOS manual.
+    '';
+    default = { };
+    example = literalExpression ''
+      { # for a local backup
+        rootBackup = {
+          paths = "/";
+          exclude = [ "/nix" ];
+          repo = "/path/to/local/repo";
+          encryption = {
+            mode = "repokey";
+            passphrase = "secret";
+          };
+          compression = "auto,lzma";
+          startAt = "weekly";
+        };
+      }
+      { # Root backing each day up to a remote backup server. We assume that you have
+        #   * created a password less key: ssh-keygen -N "" -t ed25519 -f /path/to/ssh_key
+        #     best practices are: use -t ed25519, /path/to = /run/keys
+        #   * the passphrase is in the file /run/keys/borgbackup_passphrase
+        #   * you have initialized the repository manually
+        paths = [ "/etc" "/home" ];
+        exclude = [ "/nix" "'**/.cache'" ];
+        doInit = false;
+        repo =  "user3@arep.repo.borgbase.com:repo";
+        encryption = {
+          mode = "repokey-blake2";
+          passCommand = "cat /path/to/passphrase";
+        };
+        environment = { BORG_RSH = "ssh -i /path/to/ssh_key"; };
+        compression = "auto,lzma";
+        startAt = "daily";
+    };
+    '';
+    type = types.attrsOf (types.submodule (let globalConfig = config; in
+      { name, config, ... }: {
+        options = {
+
+          paths = mkOption {
+            type = with types; nullOr (coercedTo str lib.singleton (listOf str));
+            default = null;
+            description = ''
+              Path(s) to back up.
+              Mutually exclusive with <option>dumpCommand</option>.
+            '';
+            example = "/home/user";
+          };
+
+          dumpCommand = mkOption {
+            type = with types; nullOr path;
+            default = null;
+            description = ''
+              Backup the stdout of this program instead of filesystem paths.
+              Mutually exclusive with <option>paths</option>.
+            '';
+            example = "/path/to/createZFSsend.sh";
+          };
+
+          repo = mkOption {
+            type = types.str;
+            description = "Remote or local repository to back up to.";
+            example = "user@machine:/path/to/repo";
+          };
+
+          removableDevice = mkOption {
+            type = types.bool;
+            default = false;
+            description = "Whether the repo (which must be local) is a removable device.";
+          };
+
+          archiveBaseName = mkOption {
+            type = types.nullOr (types.strMatching "[^/{}]+");
+            default = "${globalConfig.networking.hostName}-${name}";
+            defaultText = literalExpression ''"''${config.networking.hostName}-<name>"'';
+            description = ''
+              How to name the created archives. A timestamp, whose format is
+              determined by <option>dateFormat</option>, will be appended. The full
+              name can be modified at runtime (<literal>$archiveName</literal>).
+              Placeholders like <literal>{hostname}</literal> must not be used.
+              Use <literal>null</literal> for no base name.
+            '';
+          };
+
+          dateFormat = mkOption {
+            type = types.str;
+            description = ''
+              Arguments passed to <command>date</command>
+              to create a timestamp suffix for the archive name.
+            '';
+            default = "+%Y-%m-%dT%H:%M:%S";
+            example = "-u +%s";
+          };
+
+          startAt = mkOption {
+            type = with types; either str (listOf str);
+            default = "daily";
+            description = ''
+              When or how often the backup should run.
+              Must be in the format described in
+              <citerefentry><refentrytitle>systemd.time</refentrytitle>
+              <manvolnum>7</manvolnum></citerefentry>.
+              If you do not want the backup to start
+              automatically, use <literal>[ ]</literal>.
+              It will generate a systemd service borgbackup-job-NAME.
+              You may trigger it manually via systemctl restart borgbackup-job-NAME.
+            '';
+          };
+
+          persistentTimer = mkOption {
+            default = false;
+            type = types.bool;
+            example = true;
+            description = ''
+              Set the <literal>persistentTimer</literal> option for the
+              <citerefentry><refentrytitle>systemd.timer</refentrytitle>
+              <manvolnum>5</manvolnum></citerefentry>
+              which triggers the backup immediately if the last trigger
+              was missed (e.g. if the system was powered down).
+            '';
+          };
+
+          user = mkOption {
+            type = types.str;
+            description = ''
+              The user <command>borg</command> is run as.
+              User or group need read permission
+              for the specified <option>paths</option>.
+            '';
+            default = "root";
+          };
+
+          group = mkOption {
+            type = types.str;
+            description = ''
+              The group borg is run as. User or group needs read permission
+              for the specified <option>paths</option>.
+            '';
+            default = "root";
+          };
+
+          encryption.mode = mkOption {
+            type = types.enum [
+              "repokey" "keyfile"
+              "repokey-blake2" "keyfile-blake2"
+              "authenticated" "authenticated-blake2"
+              "none"
+            ];
+            description = ''
+              Encryption mode to use. Setting a mode
+              other than <literal>"none"</literal> requires
+              you to specify a <option>passCommand</option>
+              or a <option>passphrase</option>.
+            '';
+            example = "repokey-blake2";
+          };
+
+          encryption.passCommand = mkOption {
+            type = with types; nullOr str;
+            description = ''
+              A command which prints the passphrase to stdout.
+              Mutually exclusive with <option>passphrase</option>.
+            '';
+            default = null;
+            example = "cat /path/to/passphrase_file";
+          };
+
+          encryption.passphrase = mkOption {
+            type = with types; nullOr str;
+            description = ''
+              The passphrase the backups are encrypted with.
+              Mutually exclusive with <option>passCommand</option>.
+              If you do not want the passphrase to be stored in the
+              world-readable Nix store, use <option>passCommand</option>.
+            '';
+            default = null;
+          };
+
+          compression = mkOption {
+            # "auto" is optional,
+            # compression mode must be given,
+            # compression level is optional
+            type = types.strMatching "none|(auto,)?(lz4|zstd|zlib|lzma)(,[[:digit:]]{1,2})?";
+            description = ''
+              Compression method to use. Refer to
+              <command>borg help compression</command>
+              for all available options.
+            '';
+            default = "lz4";
+            example = "auto,lzma";
+          };
+
+          exclude = mkOption {
+            type = with types; listOf str;
+            description = ''
+              Exclude paths matching any of the given patterns. See
+              <command>borg help patterns</command> for pattern syntax.
+            '';
+            default = [ ];
+            example = [
+              "/home/*/.cache"
+              "/nix"
+            ];
+          };
+
+          readWritePaths = mkOption {
+            type = with types; listOf path;
+            description = ''
+              By default, borg cannot write anywhere on the system but
+              <literal>$HOME/.config/borg</literal> and <literal>$HOME/.cache/borg</literal>.
+              If, for example, your preHook script needs to dump files
+              somewhere, put those directories here.
+            '';
+            default = [ ];
+            example = [
+              "/var/backup/mysqldump"
+            ];
+          };
+
+          privateTmp = mkOption {
+            type = types.bool;
+            description = ''
+              Set the <literal>PrivateTmp</literal> option for
+              the systemd-service. Set to false if you need sockets
+              or other files from global /tmp.
+            '';
+            default = true;
+          };
+
+          doInit = mkOption {
+            type = types.bool;
+            description = ''
+              Run <command>borg init</command> if the
+              specified <option>repo</option> does not exist.
+              You should set this to <literal>false</literal>
+              if the repository is located on an external drive
+              that might not always be mounted.
+            '';
+            default = true;
+          };
+
+          appendFailedSuffix = mkOption {
+            type = types.bool;
+            description = ''
+              Append a <literal>.failed</literal> suffix
+              to the archive name, which is only removed if
+              <command>borg create</command> has a zero exit status.
+            '';
+            default = true;
+          };
+
+          prune.keep = mkOption {
+            # Specifying e.g. `prune.keep.yearly = -1`
+            # means there is no limit of yearly archives to keep
+            # The regex is for use with e.g. --keep-within 1y
+            type = with types; attrsOf (either int (strMatching "[[:digit:]]+[Hdwmy]"));
+            description = ''
+              Prune a repository by deleting all archives not matching any of the
+              specified retention options. See <command>borg help prune</command>
+              for the available options.
+            '';
+            default = { };
+            example = literalExpression ''
+              {
+                within = "1d"; # Keep all archives from the last day
+                daily = 7;
+                weekly = 4;
+                monthly = -1;  # Keep at least one archive for each month
+              }
+            '';
+          };
+
+          prune.prefix = mkOption {
+            type = types.nullOr (types.str);
+            description = ''
+              Only consider archive names starting with this prefix for pruning.
+              By default, only archives created by this job are considered.
+              Use <literal>""</literal> or <literal>null</literal> to consider all archives.
+            '';
+            default = config.archiveBaseName;
+            defaultText = literalExpression "archiveBaseName";
+          };
+
+          environment = mkOption {
+            type = with types; attrsOf str;
+            description = ''
+              Environment variables passed to the backup script.
+              You can for example specify which SSH key to use.
+            '';
+            default = { };
+            example = { BORG_RSH = "ssh -i /path/to/key"; };
+          };
+
+          preHook = mkOption {
+            type = types.lines;
+            description = ''
+              Shell commands to run before the backup.
+              This can for example be used to mount file systems.
+            '';
+            default = "";
+            example = ''
+              # To add excluded paths at runtime
+              extraCreateArgs="$extraCreateArgs --exclude /some/path"
+            '';
+          };
+
+          postInit = mkOption {
+            type = types.lines;
+            description = ''
+              Shell commands to run after <command>borg init</command>.
+            '';
+            default = "";
+          };
+
+          postCreate = mkOption {
+            type = types.lines;
+            description = ''
+              Shell commands to run after <command>borg create</command>. The name
+              of the created archive is stored in <literal>$archiveName</literal>.
+            '';
+            default = "";
+          };
+
+          postPrune = mkOption {
+            type = types.lines;
+            description = ''
+              Shell commands to run after <command>borg prune</command>.
+            '';
+            default = "";
+          };
+
+          postHook = mkOption {
+            type = types.lines;
+            description = ''
+              Shell commands to run just before exit. They are executed
+              even if a previous command exits with a non-zero exit code.
+              The latter is available as <literal>$exitStatus</literal>.
+            '';
+            default = "";
+          };
+
+          extraArgs = mkOption {
+            type = types.str;
+            description = ''
+              Additional arguments for all <command>borg</command> calls the
+              service has. Handle with care.
+            '';
+            default = "";
+            example = "--remote-path=/path/to/borg";
+          };
+
+          extraInitArgs = mkOption {
+            type = types.str;
+            description = ''
+              Additional arguments for <command>borg init</command>.
+              Can also be set at runtime using <literal>$extraInitArgs</literal>.
+            '';
+            default = "";
+            example = "--append-only";
+          };
+
+          extraCreateArgs = mkOption {
+            type = types.str;
+            description = ''
+              Additional arguments for <command>borg create</command>.
+              Can also be set at runtime using <literal>$extraCreateArgs</literal>.
+            '';
+            default = "";
+            example = "--stats --checkpoint-interval 600";
+          };
+
+          extraPruneArgs = mkOption {
+            type = types.str;
+            description = ''
+              Additional arguments for <command>borg prune</command>.
+              Can also be set at runtime using <literal>$extraPruneArgs</literal>.
+            '';
+            default = "";
+            example = "--save-space";
+          };
+
+        };
+      }
+    ));
+  };
+
+  options.services.borgbackup.repos = mkOption {
+    description = ''
+      Serve BorgBackup repositories to given public SSH keys,
+      restricting their access to the repository only.
+      See also the chapter about BorgBackup in the NixOS manual.
+      Also, clients do not need to specify the absolute path when accessing the repository,
+      i.e. <literal>user@machine:.</literal> is enough. (Note colon and dot.)
+    '';
+    default = { };
+    type = types.attrsOf (types.submodule (
+      { ... }: {
+        options = {
+          path = mkOption {
+            type = types.path;
+            description = ''
+              Where to store the backups. Note that the directory
+              is created automatically, with correct permissions.
+            '';
+            default = "/var/lib/borgbackup";
+          };
+
+          user = mkOption {
+            type = types.str;
+            description = ''
+              The user <command>borg serve</command> is run as.
+              User or group needs write permission
+              for the specified <option>path</option>.
+            '';
+            default = "borg";
+          };
+
+          group = mkOption {
+            type = types.str;
+            description = ''
+              The group <command>borg serve</command> is run as.
+              User or group needs write permission
+              for the specified <option>path</option>.
+            '';
+            default = "borg";
+          };
+
+          authorizedKeys = mkOption {
+            type = with types; listOf str;
+            description = ''
+              Public SSH keys that are given full write access to this repository.
+              You should use a different SSH key for each repository you write to, because
+              the specified keys are restricted to running <command>borg serve</command>
+              and can only access this single repository.
+            '';
+            default = [ ];
+          };
+
+          authorizedKeysAppendOnly = mkOption {
+            type = with types; listOf str;
+            description = ''
+              Public SSH keys that can only be used to append new data (archives) to the repository.
+              Note that archives can still be marked as deleted and are subsequently removed from disk
+              upon accessing the repo with full write access, e.g. when pruning.
+            '';
+            default = [ ];
+          };
+
+          allowSubRepos = mkOption {
+            type = types.bool;
+            description = ''
+              Allow clients to create repositories in subdirectories of the
+              specified <option>path</option>. These can be accessed using
+              <literal>user@machine:path/to/subrepo</literal>. Note that a
+              <option>quota</option> applies to repositories independently.
+              Therefore, if this is enabled, clients can create multiple
+              repositories and upload an arbitrary amount of data.
+            '';
+            default = false;
+          };
+
+          quota = mkOption {
+            # See the definition of parse_file_size() in src/borg/helpers/parseformat.py
+            type = with types; nullOr (strMatching "[[:digit:].]+[KMGTP]?");
+            description = ''
+              Storage quota for the repository. This quota is ensured for all
+              sub-repositories if <option>allowSubRepos</option> is enabled
+              but not for the overall storage space used.
+            '';
+            default = null;
+            example = "100G";
+          };
+
+        };
+      }
+    ));
+  };
+
+  ###### implementation
+
+  config = mkIf (with config.services.borgbackup; jobs != { } || repos != { })
+    (with config.services.borgbackup; {
+      assertions =
+        mapAttrsToList mkPassAssertion jobs
+        ++ mapAttrsToList mkKeysAssertion repos
+        ++ mapAttrsToList mkSourceAssertions jobs
+        ++ mapAttrsToList mkRemovableDeviceAssertions jobs;
+
+      system.activationScripts = mapAttrs' mkActivationScript jobs;
+
+      systemd.services =
+        # A job named "foo" is mapped to systemd.services.borgbackup-job-foo
+        mapAttrs' mkBackupService jobs
+        # A repo named "foo" is mapped to systemd.services.borgbackup-repo-foo
+        // mapAttrs' mkRepoService repos;
+
+      # A job named "foo" is mapped to systemd.timers.borgbackup-job-foo
+      # only generate the timer if interval (startAt) is set
+      systemd.timers = mapAttrs' mkBackupTimers (filterAttrs (_: cfg: cfg.startAt != []) jobs);
+
+      users = mkMerge (mapAttrsToList mkUsersConfig repos);
+
+      environment.systemPackages = with pkgs; [ borgbackup ] ++ (mapAttrsToList mkBorgWrapper jobs);
+    });
+}
diff --git a/nixos/modules/services/backup/borgbackup.xml b/nixos/modules/services/backup/borgbackup.xml
new file mode 100644
index 00000000000..8f623c93656
--- /dev/null
+++ b/nixos/modules/services/backup/borgbackup.xml
@@ -0,0 +1,209 @@
+<chapter xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xmlns:xi="http://www.w3.org/2001/XInclude"
+         version="5.0"
+         xml:id="module-borgbase">
+ <title>BorgBackup</title>
+  <para>
+  <emphasis>Source:</emphasis>
+  <filename>modules/services/backup/borgbackup.nix</filename>
+ </para>
+ <para>
+  <emphasis>Upstream documentation:</emphasis>
+  <link xlink:href="https://borgbackup.readthedocs.io/"/>
+ </para>
+ <para>
+  <link xlink:href="https://www.borgbackup.org/">BorgBackup</link> (short: Borg)
+  is a deduplicating backup program. Optionally, it supports compression and
+  authenticated encryption.
+  </para>
+  <para>
+  The main goal of Borg is to provide an efficient and secure way to backup
+  data. The data deduplication technique used makes Borg suitable for daily
+  backups since only changes are stored. The authenticated encryption technique
+  makes it suitable for backups to not fully trusted targets.
+ </para>
+  <section xml:id="module-services-backup-borgbackup-configuring">
+  <title>Configuring</title>
+  <para>
+   A complete list of options for the Borgbase module may be found
+   <link linkend="opt-services.borgbackup.jobs">here</link>.
+  </para>
+</section>
+ <section xml:id="opt-services-backup-borgbackup-local-directory">
+  <title>Basic usage for a local backup</title>
+
+  <para>
+   A very basic configuration for backing up to a locally accessible directory
+   is:
+<programlisting>
+{
+    opt.services.borgbackup.jobs = {
+      { rootBackup = {
+          paths = "/";
+          exclude = [ "/nix" "/path/to/local/repo" ];
+          repo = "/path/to/local/repo";
+          doInit = true;
+          encryption = {
+            mode = "repokey";
+            passphrase = "secret";
+          };
+          compression = "auto,lzma";
+          startAt = "weekly";
+        };
+      }
+    };
+}</programlisting>
+  </para>
+  <warning>
+    <para>
+        If you do not want the passphrase to be stored in the world-readable
+        Nix store, use passCommand. You find an example below.
+    </para>
+  </warning>
+ </section>
+<section xml:id="opt-services-backup-create-server">
+  <title>Create a borg backup server</title>
+  <para>You should use a different SSH key for each repository you write to,
+    because the specified keys are restricted to running borg serve and can only
+    access this single repository. You need the output of the generate pub file.
+  </para>
+    <para>
+<screen>
+<prompt># </prompt>sudo ssh-keygen -N '' -t ed25519 -f /run/keys/id_ed25519_my_borg_repo
+<prompt># </prompt>cat /run/keys/id_ed25519_my_borg_repo
+ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAID78zmOyA+5uPG4Ot0hfAy+sLDPU1L4AiIoRYEIVbbQ/ root@nixos</screen>
+    </para>
+    <para>
+      Add the following snippet to your NixOS configuration:
+      <programlisting>
+{
+  services.borgbackup.repos = {
+    my_borg_repo = {
+      authorizedKeys = [
+        "ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAID78zmOyA+5uPG4Ot0hfAy+sLDPU1L4AiIoRYEIVbbQ/ root@nixos"
+      ] ;
+      path = "/var/lib/my_borg_repo" ;
+    };
+  };
+}</programlisting>
+    </para>
+</section>
+
+ <section xml:id="opt-services-backup-borgbackup-remote-server">
+  <title>Backup to the borg repository server</title>
+  <para>The following NixOS snippet creates an hourly backup to the service
+    (on the host nixos) as created in the section above. We assume
+    that you have stored a secret passphrasse in the file
+    <code>/run/keys/borgbackup_passphrase</code>, which should be only
+    accessible by root
+  </para>
+  <para>
+      <programlisting>
+{
+  services.borgbackup.jobs = {
+    backupToLocalServer = {
+      paths = [ "/etc/nixos" ];
+      doInit = true;
+      repo =  "borg@nixos:." ;
+      encryption = {
+        mode = "repokey-blake2";
+        passCommand = "cat /run/keys/borgbackup_passphrase";
+      };
+      environment = { BORG_RSH = "ssh -i /run/keys/id_ed25519_my_borg_repo"; };
+      compression = "auto,lzma";
+      startAt = "hourly";
+    };
+  };
+};</programlisting>
+  </para>
+  <para>The following few commands (run as root) let you test your backup.
+      <programlisting>
+> nixos-rebuild switch
+...restarting the following units: polkit.service
+> systemctl restart borgbackup-job-backupToLocalServer
+> sleep 10
+> systemctl restart borgbackup-job-backupToLocalServer
+> export BORG_PASSPHRASE=topSecrect
+> borg list --rsh='ssh -i /run/keys/id_ed25519_my_borg_repo' borg@nixos:.
+nixos-backupToLocalServer-2020-03-30T21:46:17 Mon, 2020-03-30 21:46:19 [84feb97710954931ca384182f5f3cb90665f35cef214760abd7350fb064786ac]
+nixos-backupToLocalServer-2020-03-30T21:46:30 Mon, 2020-03-30 21:46:32 [e77321694ecd160ca2228611747c6ad1be177d6e0d894538898de7a2621b6e68]</programlisting>
+    </para>
+</section>
+
+ <section xml:id="opt-services-backup-borgbackup-borgbase">
+  <title>Backup to a hosting service</title>
+
+  <para>
+    Several companies offer <link
+      xlink:href="https://www.borgbackup.org/support/commercial.html">(paid)
+      hosting services</link> for Borg repositories.
+  </para>
+  <para>
+    To backup your home directory to borgbase you have to:
+  </para>
+  <itemizedlist>
+  <listitem>
+    <para>
+      Generate a SSH key without a password, to access the remote server. E.g.
+    </para>
+    <para>
+        <programlisting>sudo ssh-keygen -N '' -t ed25519 -f /run/keys/id_ed25519_borgbase</programlisting>
+    </para>
+  </listitem>
+  <listitem>
+    <para>
+      Create the repository on the server by following the instructions for your
+      hosting server.
+    </para>
+  </listitem>
+  <listitem>
+    <para>
+      Initialize the repository on the server. Eg.
+      <programlisting>
+sudo borg init --encryption=repokey-blake2  \
+    -rsh "ssh -i /run/keys/id_ed25519_borgbase" \
+    zzz2aaaaa@zzz2aaaaa.repo.borgbase.com:repo</programlisting>
+  </para>
+  </listitem>
+  <listitem>
+<para>Add it to your NixOS configuration, e.g.
+<programlisting>
+{
+    services.borgbackup.jobs = {
+    my_Remote_Backup = {
+        paths = [ "/" ];
+        exclude = [ "/nix" "'**/.cache'" ];
+        repo =  "zzz2aaaaa@zzz2aaaaa.repo.borgbase.com:repo";
+          encryption = {
+          mode = "repokey-blake2";
+          passCommand = "cat /run/keys/borgbackup_passphrase";
+        };
+        BORG_RSH = "ssh -i /run/keys/id_ed25519_borgbase";
+        compression = "auto,lzma";
+        startAt = "daily";
+    };
+  };
+}}</programlisting>
+  </para>
+  </listitem>
+</itemizedlist>
+ </section>
+  <section xml:id="opt-services-backup-borgbackup-vorta">
+  <title>Vorta backup client for the desktop</title>
+  <para>
+    Vorta is a backup client for macOS and Linux desktops. It integrates the
+    mighty BorgBackup with your desktop environment to protect your data from
+    disk failure, ransomware and theft.
+  </para>
+  <para>
+   It can be installed in NixOS e.g. by adding <package>pkgs.vorta</package>
+   to <xref linkend="opt-environment.systemPackages" />.
+  </para>
+  <para>
+    Details about using Vorta can be found under <link
+      xlink:href="https://vorta.borgbase.com/usage">https://vorta.borgbase.com
+      </link>.
+  </para>
+ </section>
+</chapter>
diff --git a/nixos/modules/services/backup/borgmatic.nix b/nixos/modules/services/backup/borgmatic.nix
new file mode 100644
index 00000000000..5e5c0bbeccc
--- /dev/null
+++ b/nixos/modules/services/backup/borgmatic.nix
@@ -0,0 +1,57 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.borgmatic;
+  cfgfile = pkgs.writeText "config.yaml" (builtins.toJSON cfg.settings);
+in {
+  options.services.borgmatic = {
+    enable = mkEnableOption "borgmatic";
+
+    settings = mkOption {
+      description = ''
+        See https://torsion.org/borgmatic/docs/reference/configuration/
+      '';
+      type = types.submodule {
+        freeformType = with lib.types; attrsOf anything;
+        options.location = {
+          source_directories = mkOption {
+            type = types.listOf types.str;
+            description = ''
+              List of source directories to backup (required). Globs and
+              tildes are expanded.
+            '';
+            example = [ "/home" "/etc" "/var/log/syslog*" ];
+          };
+          repositories = mkOption {
+            type = types.listOf types.str;
+            description = ''
+              Paths to local or remote repositories (required). Tildes are
+              expanded. Multiple repositories are backed up to in
+              sequence. Borg placeholders can be used. See the output of
+              "borg help placeholders" for details. See ssh_command for
+              SSH options like identity file or port. If systemd service
+              is used, then add local repository paths in the systemd
+              service file to the ReadWritePaths list.
+            '';
+            example = [
+              "user@backupserver:sourcehostname.borg"
+              "user@backupserver:{fqdn}"
+            ];
+          };
+        };
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+
+    environment.systemPackages = [ pkgs.borgmatic ];
+
+    environment.etc."borgmatic/config.yaml".source = cfgfile;
+
+    systemd.packages = [ pkgs.borgmatic ];
+
+  };
+}
diff --git a/nixos/modules/services/backup/btrbk.nix b/nixos/modules/services/backup/btrbk.nix
new file mode 100644
index 00000000000..0c00b934405
--- /dev/null
+++ b/nixos/modules/services/backup/btrbk.nix
@@ -0,0 +1,220 @@
+{ config, pkgs, lib, ... }:
+let
+  cfg = config.services.btrbk;
+  sshEnabled = cfg.sshAccess != [ ];
+  serviceEnabled = cfg.instances != { };
+  attr2Lines = attr:
+    let
+      pairs = lib.attrsets.mapAttrsToList (name: value: { inherit name value; }) attr;
+      isSubsection = value:
+        if builtins.isAttrs value then true
+        else if builtins.isString value then false
+        else throw "invalid type in btrbk config ${builtins.typeOf value}";
+      sortedPairs = lib.lists.partition (x: isSubsection x.value) pairs;
+    in
+    lib.flatten (
+      # non subsections go first
+      (
+        map (pair: [ "${pair.name} ${pair.value}" ]) sortedPairs.wrong
+      )
+      ++ # subsections go last
+      (
+        map
+          (
+            pair:
+            lib.mapAttrsToList
+              (
+                childname: value:
+                  [ "${pair.name} ${childname}" ] ++ (map (x: " " + x) (attr2Lines value))
+              )
+              pair.value
+          )
+          sortedPairs.right
+      )
+    )
+  ;
+  addDefaults = settings: { backend = "btrfs-progs-sudo"; } // settings;
+  mkConfigFile = settings: lib.concatStringsSep "\n" (attr2Lines (addDefaults settings));
+  mkTestedConfigFile = name: settings:
+    let
+      configFile = pkgs.writeText "btrbk-${name}.conf" (mkConfigFile settings);
+    in
+    pkgs.runCommand "btrbk-${name}-tested.conf" { } ''
+      mkdir foo
+      cp ${configFile} $out
+      if (set +o pipefail; ${pkgs.btrbk}/bin/btrbk -c $out ls foo 2>&1 | grep $out);
+      then
+      echo btrbk configuration is invalid
+      cat $out
+      exit 1
+      fi;
+    '';
+in
+{
+  options = {
+    services.btrbk = {
+      extraPackages = lib.mkOption {
+        description = "Extra packages for btrbk, like compression utilities for <literal>stream_compress</literal>";
+        type = lib.types.listOf lib.types.package;
+        default = [ ];
+        example = lib.literalExpression "[ pkgs.xz ]";
+      };
+      niceness = lib.mkOption {
+        description = "Niceness for local instances of btrbk. Also applies to remote ones connecting via ssh when positive.";
+        type = lib.types.ints.between (-20) 19;
+        default = 10;
+      };
+      ioSchedulingClass = lib.mkOption {
+        description = "IO scheduling class for btrbk (see ionice(1) for a quick description). Applies to local instances, and remote ones connecting by ssh if set to idle.";
+        type = lib.types.enum [ "idle" "best-effort" "realtime" ];
+        default = "best-effort";
+      };
+      instances = lib.mkOption {
+        description = "Set of btrbk instances. The instance named <literal>btrbk</literal> is the default one.";
+        type = with lib.types;
+          attrsOf (
+            submodule {
+              options = {
+                onCalendar = lib.mkOption {
+                  type = lib.types.str;
+                  default = "daily";
+                  description = "How often this btrbk instance is started. See systemd.time(7) for more information about the format.";
+                };
+                settings = lib.mkOption {
+                  type = let t = lib.types.attrsOf (lib.types.either lib.types.str (t // { description = "instances of this type recursively"; })); in t;
+                  default = { };
+                  example = {
+                    snapshot_preserve_min = "2d";
+                    snapshot_preserve = "14d";
+                    volume = {
+                      "/mnt/btr_pool" = {
+                        target = "/mnt/btr_backup/mylaptop";
+                        subvolume = {
+                          "rootfs" = { };
+                          "home" = { snapshot_create = "always"; };
+                        };
+                      };
+                    };
+                  };
+                  description = "configuration options for btrbk. Nested attrsets translate to subsections.";
+                };
+              };
+            }
+          );
+        default = { };
+      };
+      sshAccess = lib.mkOption {
+        description = "SSH keys that should be able to make or push snapshots on this system remotely with btrbk";
+        type = with lib.types; listOf (
+          submodule {
+            options = {
+              key = lib.mkOption {
+                type = str;
+                description = "SSH public key allowed to login as user <literal>btrbk</literal> to run remote backups.";
+              };
+              roles = lib.mkOption {
+                type = listOf (enum [ "info" "source" "target" "delete" "snapshot" "send" "receive" ]);
+                example = [ "source" "info" "send" ];
+                description = "What actions can be performed with this SSH key. See ssh_filter_btrbk(1) for details";
+              };
+            };
+          }
+        );
+        default = [ ];
+      };
+    };
+
+  };
+  config = lib.mkIf (sshEnabled || serviceEnabled) {
+    environment.systemPackages = [ pkgs.btrbk ] ++ cfg.extraPackages;
+    security.sudo.extraRules = [
+      {
+        users = [ "btrbk" ];
+        commands = [
+          { command = "${pkgs.btrfs-progs}/bin/btrfs"; options = [ "NOPASSWD" ]; }
+          { command = "${pkgs.coreutils}/bin/mkdir"; options = [ "NOPASSWD" ]; }
+          { command = "${pkgs.coreutils}/bin/readlink"; options = [ "NOPASSWD" ]; }
+          # for ssh, they are not the same than the one hard coded in ${pkgs.btrbk}
+          { command = "/run/current-system/bin/btrfs"; options = [ "NOPASSWD" ]; }
+          { command = "/run/current-system/sw/bin/mkdir"; options = [ "NOPASSWD" ]; }
+          { command = "/run/current-system/sw/bin/readlink"; options = [ "NOPASSWD" ]; }
+        ];
+      }
+    ];
+    users.users.btrbk = {
+      isSystemUser = true;
+      # ssh needs a home directory
+      home = "/var/lib/btrbk";
+      createHome = true;
+      shell = "${pkgs.bash}/bin/bash";
+      group = "btrbk";
+      openssh.authorizedKeys.keys = map
+        (
+          v:
+          let
+            options = lib.concatMapStringsSep " " (x: "--" + x) v.roles;
+            ioniceClass = {
+              "idle" = 3;
+              "best-effort" = 2;
+              "realtime" = 1;
+            }.${cfg.ioSchedulingClass};
+          in
+          ''command="${pkgs.util-linux}/bin/ionice -t -c ${toString ioniceClass} ${lib.optionalString (cfg.niceness >= 1) "${pkgs.coreutils}/bin/nice -n ${toString cfg.niceness}"} ${pkgs.btrbk}/share/btrbk/scripts/ssh_filter_btrbk.sh --sudo ${options}" ${v.key}''
+        )
+        cfg.sshAccess;
+    };
+    users.groups.btrbk = { };
+    systemd.tmpfiles.rules = [
+      "d /var/lib/btrbk 0750 btrbk btrbk"
+      "d /var/lib/btrbk/.ssh 0700 btrbk btrbk"
+      "f /var/lib/btrbk/.ssh/config 0700 btrbk btrbk - StrictHostKeyChecking=accept-new"
+    ];
+    environment.etc = lib.mapAttrs'
+      (
+        name: instance: {
+          name = "btrbk/${name}.conf";
+          value.source = mkTestedConfigFile name instance.settings;
+        }
+      )
+      cfg.instances;
+    systemd.services = lib.mapAttrs'
+      (
+        name: _: {
+          name = "btrbk-${name}";
+          value = {
+            description = "Takes BTRFS snapshots and maintains retention policies.";
+            unitConfig.Documentation = "man:btrbk(1)";
+            path = [ "/run/wrappers" ] ++ cfg.extraPackages;
+            serviceConfig = {
+              User = "btrbk";
+              Group = "btrbk";
+              Type = "oneshot";
+              ExecStart = "${pkgs.btrbk}/bin/btrbk -c /etc/btrbk/${name}.conf run";
+              Nice = cfg.niceness;
+              IOSchedulingClass = cfg.ioSchedulingClass;
+              StateDirectory = "btrbk";
+            };
+          };
+        }
+      )
+      cfg.instances;
+
+    systemd.timers = lib.mapAttrs'
+      (
+        name: instance: {
+          name = "btrbk-${name}";
+          value = {
+            description = "Timer to take BTRFS snapshots and maintain retention policies.";
+            wantedBy = [ "timers.target" ];
+            timerConfig = {
+              OnCalendar = instance.onCalendar;
+              AccuracySec = "10min";
+              Persistent = true;
+            };
+          };
+        }
+      )
+      cfg.instances;
+  };
+
+}
diff --git a/nixos/modules/services/backup/duplicati.nix b/nixos/modules/services/backup/duplicati.nix
new file mode 100644
index 00000000000..97864c44691
--- /dev/null
+++ b/nixos/modules/services/backup/duplicati.nix
@@ -0,0 +1,86 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+
+let
+  cfg = config.services.duplicati;
+in
+{
+  options = {
+    services.duplicati = {
+      enable = mkEnableOption "Duplicati";
+
+      port = mkOption {
+        default = 8200;
+        type = types.int;
+        description = ''
+          Port serving the web interface
+        '';
+      };
+
+      dataDir = mkOption {
+        type = types.str;
+        default = "/var/lib/duplicati";
+        description = ''
+          The directory where Duplicati stores its data files.
+
+          <note><para>
+            If left as the default value this directory will automatically be created
+            before the Duplicati server starts, otherwise you are responsible for ensuring
+            the directory exists with appropriate ownership and permissions.
+          </para></note>
+        '';
+      };
+
+      interface = mkOption {
+        default = "127.0.0.1";
+        type = types.str;
+        description = ''
+          Listening interface for the web UI
+          Set it to "any" to listen on all available interfaces
+        '';
+      };
+
+      user = mkOption {
+        default = "duplicati";
+        type = types.str;
+        description = ''
+          Duplicati runs as it's own user. It will only be able to backup world-readable files.
+          Run as root with special care.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [ pkgs.duplicati ];
+
+    systemd.services.duplicati = {
+      description = "Duplicati backup";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = mkMerge [
+        {
+          User = cfg.user;
+          Group = "duplicati";
+          ExecStart = "${pkgs.duplicati}/bin/duplicati-server --webservice-interface=${cfg.interface} --webservice-port=${toString cfg.port} --server-datafolder=${cfg.dataDir}";
+          Restart = "on-failure";
+        }
+        (mkIf (cfg.dataDir == "/var/lib/duplicati") {
+          StateDirectory = "duplicati";
+        })
+      ];
+    };
+
+    users.users = lib.optionalAttrs (cfg.user == "duplicati") {
+      duplicati = {
+        uid = config.ids.uids.duplicati;
+        home = cfg.dataDir;
+        group = "duplicati";
+      };
+    };
+    users.groups.duplicati.gid = config.ids.gids.duplicati;
+
+  };
+}
+
diff --git a/nixos/modules/services/backup/duplicity.nix b/nixos/modules/services/backup/duplicity.nix
new file mode 100644
index 00000000000..6949fa8b995
--- /dev/null
+++ b/nixos/modules/services/backup/duplicity.nix
@@ -0,0 +1,196 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+let
+  cfg = config.services.duplicity;
+
+  stateDirectory = "/var/lib/duplicity";
+
+  localTarget =
+    if hasPrefix "file://" cfg.targetUrl
+    then removePrefix "file://" cfg.targetUrl else null;
+
+in
+{
+  options.services.duplicity = {
+    enable = mkEnableOption "backups with duplicity";
+
+    root = mkOption {
+      type = types.path;
+      default = "/";
+      description = ''
+        Root directory to backup.
+      '';
+    };
+
+    include = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = [ "/home" ];
+      description = ''
+        List of paths to include into the backups. See the FILE SELECTION
+        section in <citerefentry><refentrytitle>duplicity</refentrytitle>
+        <manvolnum>1</manvolnum></citerefentry> for details on the syntax.
+      '';
+    };
+
+    exclude = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      description = ''
+        List of paths to exclude from backups. See the FILE SELECTION section in
+        <citerefentry><refentrytitle>duplicity</refentrytitle>
+        <manvolnum>1</manvolnum></citerefentry> for details on the syntax.
+      '';
+    };
+
+    targetUrl = mkOption {
+      type = types.str;
+      example = "s3://host:port/prefix";
+      description = ''
+        Target url to backup to. See the URL FORMAT section in
+        <citerefentry><refentrytitle>duplicity</refentrytitle>
+        <manvolnum>1</manvolnum></citerefentry> for supported urls.
+      '';
+    };
+
+    secretFile = mkOption {
+      type = types.nullOr types.path;
+      default = null;
+      description = ''
+        Path of a file containing secrets (gpg passphrase, access key...) in
+        the format of EnvironmentFile as described by
+        <citerefentry><refentrytitle>systemd.exec</refentrytitle>
+        <manvolnum>5</manvolnum></citerefentry>. For example:
+        <programlisting>
+        PASSPHRASE=<replaceable>...</replaceable>
+        AWS_ACCESS_KEY_ID=<replaceable>...</replaceable>
+        AWS_SECRET_ACCESS_KEY=<replaceable>...</replaceable>
+        </programlisting>
+      '';
+    };
+
+    frequency = mkOption {
+      type = types.nullOr types.str;
+      default = "daily";
+      description = ''
+        Run duplicity with the given frequency (see
+        <citerefentry><refentrytitle>systemd.time</refentrytitle>
+        <manvolnum>7</manvolnum></citerefentry> for the format).
+        If null, do not run automatically.
+      '';
+    };
+
+    extraFlags = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = [ "--backend-retry-delay" "100" ];
+      description = ''
+        Extra command-line flags passed to duplicity. See
+        <citerefentry><refentrytitle>duplicity</refentrytitle>
+        <manvolnum>1</manvolnum></citerefentry>.
+      '';
+    };
+
+    fullIfOlderThan = mkOption {
+      type = types.str;
+      default = "never";
+      example = "1M";
+      description = ''
+        If <literal>"never"</literal> (the default) always do incremental
+        backups (the first backup will be a full backup, of course).  If
+        <literal>"always"</literal> always do full backups.  Otherwise, this
+        must be a string representing a duration. Full backups will be made
+        when the latest full backup is older than this duration. If this is not
+        the case, an incremental backup is performed.
+      '';
+    };
+
+    cleanup = {
+      maxAge = mkOption {
+        type = types.nullOr types.str;
+        default = null;
+        example = "6M";
+        description = ''
+          If non-null, delete all backup sets older than the given time.  Old backup sets
+          will not be deleted if backup sets newer than time depend on them.
+        '';
+      };
+      maxFull = mkOption {
+        type = types.nullOr types.int;
+        default = null;
+        example = 2;
+        description = ''
+          If non-null, delete all backups sets that are older than the count:th last full
+          backup (in other words, keep the last count full backups and
+          associated incremental sets).
+        '';
+      };
+      maxIncr = mkOption {
+        type = types.nullOr types.int;
+        default = null;
+        example = 1;
+        description = ''
+          If non-null, delete incremental sets of all backups sets that are
+          older than the count:th last full backup (in other words, keep only
+          old full backups and not their increments).
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd = {
+      services.duplicity = {
+        description = "backup files with duplicity";
+
+        environment.HOME = stateDirectory;
+
+        script =
+          let
+            target = escapeShellArg cfg.targetUrl;
+            extra = escapeShellArgs ([ "--archive-dir" stateDirectory ] ++ cfg.extraFlags);
+            dup = "${pkgs.duplicity}/bin/duplicity";
+          in
+          ''
+            set -x
+            ${dup} cleanup ${target} --force ${extra}
+            ${lib.optionalString (cfg.cleanup.maxAge != null) "${dup} remove-older-than ${lib.escapeShellArg cfg.cleanup.maxAge} ${target} --force ${extra}"}
+            ${lib.optionalString (cfg.cleanup.maxFull != null) "${dup} remove-all-but-n-full ${toString cfg.cleanup.maxFull} ${target} --force ${extra}"}
+            ${lib.optionalString (cfg.cleanup.maxIncr != null) "${dup} remove-all-inc-of-but-n-full ${toString cfg.cleanup.maxIncr} ${target} --force ${extra}"}
+            exec ${dup} ${if cfg.fullIfOlderThan == "always" then "full" else "incr"} ${lib.escapeShellArgs (
+              [ cfg.root cfg.targetUrl ]
+              ++ concatMap (p: [ "--include" p ]) cfg.include
+              ++ concatMap (p: [ "--exclude" p ]) cfg.exclude
+              ++ (lib.optionals (cfg.fullIfOlderThan != "never" && cfg.fullIfOlderThan != "always") [ "--full-if-older-than" cfg.fullIfOlderThan ])
+              )} ${extra}
+          '';
+        serviceConfig = {
+          PrivateTmp = true;
+          ProtectSystem = "strict";
+          ProtectHome = "read-only";
+          StateDirectory = baseNameOf stateDirectory;
+        } // optionalAttrs (localTarget != null) {
+          ReadWritePaths = localTarget;
+        } // optionalAttrs (cfg.secretFile != null) {
+          EnvironmentFile = cfg.secretFile;
+        };
+      } // optionalAttrs (cfg.frequency != null) {
+        startAt = cfg.frequency;
+      };
+
+      tmpfiles.rules = optional (localTarget != null) "d ${localTarget} 0700 root root -";
+    };
+
+    assertions = singleton {
+      # Duplicity will fail if the last file selection option is an include. It
+      # is not always possible to detect but this simple case can be caught.
+      assertion = cfg.include != [ ] -> cfg.exclude != [ ] || cfg.extraFlags != [ ];
+      message = ''
+        Duplicity will fail if you only specify included paths ("Because the
+        default is to include all files, the expression is redundant. Exiting
+        because this probably isn't what you meant.")
+      '';
+    };
+  };
+}
diff --git a/nixos/modules/services/backup/mysql-backup.nix b/nixos/modules/services/backup/mysql-backup.nix
new file mode 100644
index 00000000000..c40a0b5abc4
--- /dev/null
+++ b/nixos/modules/services/backup/mysql-backup.nix
@@ -0,0 +1,130 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  inherit (pkgs) mariadb gzip;
+
+  cfg = config.services.mysqlBackup;
+  defaultUser = "mysqlbackup";
+
+  backupScript = ''
+    set -o pipefail
+    failed=""
+    ${concatMapStringsSep "\n" backupDatabaseScript cfg.databases}
+    if [ -n "$failed" ]; then
+      echo "Backup of database(s) failed:$failed"
+      exit 1
+    fi
+  '';
+  backupDatabaseScript = db: ''
+    dest="${cfg.location}/${db}.gz"
+    if ${mariadb}/bin/mysqldump ${if cfg.singleTransaction then "--single-transaction" else ""} ${db} | ${gzip}/bin/gzip -c > $dest.tmp; then
+      mv $dest.tmp $dest
+      echo "Backed up to $dest"
+    else
+      echo "Failed to back up to $dest"
+      rm -f $dest.tmp
+      failed="$failed ${db}"
+    fi
+  '';
+
+in
+
+{
+  options = {
+
+    services.mysqlBackup = {
+
+      enable = mkEnableOption "MySQL backups";
+
+      calendar = mkOption {
+        type = types.str;
+        default = "01:15:00";
+        description = ''
+          Configured when to run the backup service systemd unit (DayOfWeek Year-Month-Day Hour:Minute:Second).
+        '';
+      };
+
+      user = mkOption {
+        type = types.str;
+        default = defaultUser;
+        description = ''
+          User to be used to perform backup.
+        '';
+      };
+
+      databases = mkOption {
+        default = [];
+        type = types.listOf types.str;
+        description = ''
+          List of database names to dump.
+        '';
+      };
+
+      location = mkOption {
+        type = types.path;
+        default = "/var/backup/mysql";
+        description = ''
+          Location to put the gzipped MySQL database dumps.
+        '';
+      };
+
+      singleTransaction = mkOption {
+        default = false;
+        type = types.bool;
+        description = ''
+          Whether to create database dump in a single transaction
+        '';
+      };
+    };
+
+  };
+
+  config = mkIf cfg.enable {
+    users.users = optionalAttrs (cfg.user == defaultUser) {
+      ${defaultUser} = {
+        isSystemUser = true;
+        createHome = false;
+        home = cfg.location;
+        group = "nogroup";
+      };
+    };
+
+    services.mysql.ensureUsers = [{
+      name = cfg.user;
+      ensurePermissions = with lib;
+        let
+          privs = "SELECT, SHOW VIEW, TRIGGER, LOCK TABLES";
+          grant = db: nameValuePair "${db}.*" privs;
+        in
+          listToAttrs (map grant cfg.databases);
+    }];
+
+    systemd = {
+      timers.mysql-backup = {
+        description = "Mysql backup timer";
+        wantedBy = [ "timers.target" ];
+        timerConfig = {
+          OnCalendar = cfg.calendar;
+          AccuracySec = "5m";
+          Unit = "mysql-backup.service";
+        };
+      };
+      services.mysql-backup = {
+        description = "MySQL backup service";
+        enable = true;
+        serviceConfig = {
+          Type = "oneshot";
+          User = cfg.user;
+        };
+        script = backupScript;
+      };
+      tmpfiles.rules = [
+        "d ${cfg.location} 0700 ${cfg.user} - - -"
+      ];
+    };
+  };
+
+}
diff --git a/nixos/modules/services/backup/postgresql-backup.nix b/nixos/modules/services/backup/postgresql-backup.nix
new file mode 100644
index 00000000000..562458eb457
--- /dev/null
+++ b/nixos/modules/services/backup/postgresql-backup.nix
@@ -0,0 +1,164 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.services.postgresqlBackup;
+
+  postgresqlBackupService = db: dumpCmd:
+    let
+      compressSuffixes = {
+        "none" = "";
+        "gzip" = ".gz";
+        "zstd" = ".zstd";
+      };
+      compressSuffix = getAttr cfg.compression compressSuffixes;
+
+      compressCmd = getAttr cfg.compression {
+        "none" = "cat";
+        "gzip" = "${pkgs.gzip}/bin/gzip -c";
+        "zstd" = "${pkgs.zstd}/bin/zstd -c";
+      };
+
+      mkSqlPath = prefix: suffix: "${cfg.location}/${db}${prefix}.sql${suffix}";
+      curFile = mkSqlPath "" compressSuffix;
+      prevFile = mkSqlPath ".prev" compressSuffix;
+      prevFiles = map (mkSqlPath ".prev") (attrValues compressSuffixes);
+      inProgressFile = mkSqlPath ".in-progress" compressSuffix;
+    in {
+      enable = true;
+
+      description = "Backup of ${db} database(s)";
+
+      requires = [ "postgresql.service" ];
+
+      path = [ pkgs.coreutils config.services.postgresql.package ];
+
+      script = ''
+        set -e -o pipefail
+
+        umask 0077 # ensure backup is only readable by postgres user
+
+        if [ -e ${curFile} ]; then
+          rm -f ${toString prevFiles}
+          mv ${curFile} ${prevFile}
+        fi
+
+        ${dumpCmd} \
+          | ${compressCmd} \
+          > ${inProgressFile}
+
+        mv ${inProgressFile} ${curFile}
+      '';
+
+      serviceConfig = {
+        Type = "oneshot";
+        User = "postgres";
+      };
+
+      startAt = cfg.startAt;
+    };
+
+in {
+
+  imports = [
+    (mkRemovedOptionModule [ "services" "postgresqlBackup" "period" ] ''
+       A systemd timer is now used instead of cron.
+       The starting time can be configured via <literal>services.postgresqlBackup.startAt</literal>.
+    '')
+  ];
+
+  options = {
+    services.postgresqlBackup = {
+      enable = mkEnableOption "PostgreSQL dumps";
+
+      startAt = mkOption {
+        default = "*-*-* 01:15:00";
+        type = with types; either (listOf str) str;
+        description = ''
+          This option defines (see <literal>systemd.time</literal> for format) when the
+          databases should be dumped.
+          The default is to update at 01:15 (at night) every day.
+        '';
+      };
+
+      backupAll = mkOption {
+        default = cfg.databases == [];
+        defaultText = literalExpression "services.postgresqlBackup.databases == []";
+        type = lib.types.bool;
+        description = ''
+          Backup all databases using pg_dumpall.
+          This option is mutual exclusive to
+          <literal>services.postgresqlBackup.databases</literal>.
+          The resulting backup dump will have the name all.sql.gz.
+          This option is the default if no databases are specified.
+        '';
+      };
+
+      databases = mkOption {
+        default = [];
+        type = types.listOf types.str;
+        description = ''
+          List of database names to dump.
+        '';
+      };
+
+      location = mkOption {
+        default = "/var/backup/postgresql";
+        type = types.path;
+        description = ''
+          Path of directory where the PostgreSQL database dumps will be placed.
+        '';
+      };
+
+      pgdumpOptions = mkOption {
+        type = types.separatedString " ";
+        default = "-C";
+        description = ''
+          Command line options for pg_dump. This options is not used
+          if <literal>config.services.postgresqlBackup.backupAll</literal> is enabled.
+          Note that config.services.postgresqlBackup.backupAll is also active,
+          when no databases where specified.
+        '';
+      };
+
+      compression = mkOption {
+        type = types.enum ["none" "gzip" "zstd"];
+        default = "gzip";
+        description = ''
+          The type of compression to use on the generated database dump.
+        '';
+      };
+    };
+
+  };
+
+  config = mkMerge [
+    {
+      assertions = [{
+        assertion = cfg.backupAll -> cfg.databases == [];
+        message = "config.services.postgresqlBackup.backupAll cannot be used together with config.services.postgresqlBackup.databases";
+      }];
+    }
+    (mkIf cfg.enable {
+      systemd.tmpfiles.rules = [
+        "d '${cfg.location}' 0700 postgres - - -"
+      ];
+    })
+    (mkIf (cfg.enable && cfg.backupAll) {
+      systemd.services.postgresqlBackup =
+        postgresqlBackupService "all" "pg_dumpall";
+    })
+    (mkIf (cfg.enable && !cfg.backupAll) {
+      systemd.services = listToAttrs (map (db:
+        let
+          cmd = "pg_dump ${cfg.pgdumpOptions} ${db}";
+        in {
+          name = "postgresqlBackup-${db}";
+          value = postgresqlBackupService db cmd;
+        }) cfg.databases);
+    })
+  ];
+
+}
diff --git a/nixos/modules/services/backup/postgresql-wal-receiver.nix b/nixos/modules/services/backup/postgresql-wal-receiver.nix
new file mode 100644
index 00000000000..32643adfdae
--- /dev/null
+++ b/nixos/modules/services/backup/postgresql-wal-receiver.nix
@@ -0,0 +1,204 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  receiverSubmodule = {
+    options = {
+      postgresqlPackage = mkOption {
+        type = types.package;
+        example = literalExpression "pkgs.postgresql_11";
+        description = ''
+          PostgreSQL package to use.
+        '';
+      };
+
+      directory = mkOption {
+        type = types.path;
+        example = literalExpression "/mnt/pg_wal/main/";
+        description = ''
+          Directory to write the output to.
+        '';
+      };
+
+      statusInterval = mkOption {
+        type = types.int;
+        default = 10;
+        description = ''
+          Specifies the number of seconds between status packets sent back to the server.
+          This allows for easier monitoring of the progress from server.
+          A value of zero disables the periodic status updates completely,
+          although an update will still be sent when requested by the server, to avoid timeout disconnect.
+        '';
+      };
+
+      slot = mkOption {
+        type = types.str;
+        default = "";
+        example = "some_slot_name";
+        description = ''
+          Require <command>pg_receivewal</command> to use an existing replication slot (see
+          <link xlink:href="https://www.postgresql.org/docs/current/warm-standby.html#STREAMING-REPLICATION-SLOTS">Section 26.2.6 of the PostgreSQL manual</link>).
+          When this option is used, <command>pg_receivewal</command> will report a flush position to the server,
+          indicating when each segment has been synchronized to disk so that the server can remove that segment if it is not otherwise needed.
+
+          When the replication client of <command>pg_receivewal</command> is configured on the server as a synchronous standby,
+          then using a replication slot will report the flush position to the server, but only when a WAL file is closed.
+          Therefore, that configuration will cause transactions on the primary to wait for a long time and effectively not work satisfactorily.
+          The option <option>synchronous</option> must be specified in addition to make this work correctly.
+        '';
+      };
+
+      synchronous = mkOption {
+        type = types.bool;
+        default = false;
+        description = ''
+          Flush the WAL data to disk immediately after it has been received.
+          Also send a status packet back to the server immediately after flushing, regardless of <option>statusInterval</option>.
+
+          This option should be specified if the replication client of <command>pg_receivewal</command> is configured on the server as a synchronous standby,
+          to ensure that timely feedback is sent to the server.
+        '';
+      };
+
+      compress = mkOption {
+        type = types.ints.between 0 9;
+        default = 0;
+        description = ''
+          Enables gzip compression of write-ahead logs, and specifies the compression level
+          (<literal>0</literal> through <literal>9</literal>, <literal>0</literal> being no compression and <literal>9</literal> being best compression).
+          The suffix <literal>.gz</literal> will automatically be added to all filenames.
+
+          This option requires PostgreSQL >= 10.
+        '';
+      };
+
+      connection = mkOption {
+        type = types.str;
+        example = "postgresql://user@somehost";
+        description = ''
+          Specifies parameters used to connect to the server, as a connection string.
+          See <link xlink:href="https://www.postgresql.org/docs/current/libpq-connect.html#LIBPQ-CONNSTRING">Section 34.1.1 of the PostgreSQL manual</link> for more information.
+
+          Because <command>pg_receivewal</command> doesn't connect to any particular database in the cluster,
+          database name in the connection string will be ignored.
+        '';
+      };
+
+      extraArgs = mkOption {
+        type = with types; listOf str;
+        default = [ ];
+        example = literalExpression ''
+          [
+            "--no-sync"
+          ]
+        '';
+        description = ''
+          A list of extra arguments to pass to the <command>pg_receivewal</command> command.
+        '';
+      };
+
+      environment = mkOption {
+        type = with types; attrsOf str;
+        default = { };
+        example = literalExpression ''
+          {
+            PGPASSFILE = "/private/passfile";
+            PGSSLMODE = "require";
+          }
+        '';
+        description = ''
+          Environment variables passed to the service.
+          Usable parameters are listed in <link xlink:href="https://www.postgresql.org/docs/current/libpq-envars.html">Section 34.14 of the PostgreSQL manual</link>.
+        '';
+      };
+    };
+  };
+
+in {
+  options = {
+    services.postgresqlWalReceiver = {
+      receivers = mkOption {
+        type = with types; attrsOf (submodule receiverSubmodule);
+        default = { };
+        example = literalExpression ''
+          {
+            main = {
+              postgresqlPackage = pkgs.postgresql_11;
+              directory = /mnt/pg_wal/main/;
+              slot = "main_wal_receiver";
+              connection = "postgresql://user@somehost";
+            };
+          }
+        '';
+        description = ''
+          PostgreSQL WAL receivers.
+          Stream write-ahead logs from a PostgreSQL server using <command>pg_receivewal</command> (formerly <command>pg_receivexlog</command>).
+          See <link xlink:href="https://www.postgresql.org/docs/current/app-pgreceivewal.html">the man page</link> for more information.
+        '';
+      };
+    };
+  };
+
+  config = let
+    receivers = config.services.postgresqlWalReceiver.receivers;
+  in mkIf (receivers != { }) {
+    users = {
+      users.postgres = {
+        uid = config.ids.uids.postgres;
+        group = "postgres";
+        description = "PostgreSQL server user";
+      };
+
+      groups.postgres = {
+        gid = config.ids.gids.postgres;
+      };
+    };
+
+    assertions = concatLists (attrsets.mapAttrsToList (name: config: [
+      {
+        assertion = config.compress > 0 -> versionAtLeast config.postgresqlPackage.version "10";
+        message = "Invalid configuration for WAL receiver \"${name}\": compress requires PostgreSQL version >= 10.";
+      }
+    ]) receivers);
+
+    systemd.tmpfiles.rules = mapAttrsToList (name: config: ''
+      d ${escapeShellArg config.directory} 0750 postgres postgres - -
+    '') receivers;
+
+    systemd.services = with attrsets; mapAttrs' (name: config: nameValuePair "postgresql-wal-receiver-${name}" {
+      description = "PostgreSQL WAL receiver (${name})";
+      wantedBy = [ "multi-user.target" ];
+      startLimitIntervalSec = 0; # retry forever, useful in case of network disruption
+
+      serviceConfig = {
+        User = "postgres";
+        Group = "postgres";
+        KillSignal = "SIGINT";
+        Restart = "always";
+        RestartSec = 60;
+      };
+
+      inherit (config) environment;
+
+      script = let
+        receiverCommand = postgresqlPackage:
+         if (versionAtLeast postgresqlPackage.version "10")
+           then "${postgresqlPackage}/bin/pg_receivewal"
+           else "${postgresqlPackage}/bin/pg_receivexlog";
+      in ''
+        ${receiverCommand config.postgresqlPackage} \
+          --no-password \
+          --directory=${escapeShellArg config.directory} \
+          --status-interval=${toString config.statusInterval} \
+          --dbname=${escapeShellArg config.connection} \
+          ${optionalString (config.compress > 0) "--compress=${toString config.compress}"} \
+          ${optionalString (config.slot != "") "--slot=${escapeShellArg config.slot}"} \
+          ${optionalString config.synchronous "--synchronous"} \
+          ${concatStringsSep " " config.extraArgs}
+      '';
+    }) receivers;
+  };
+
+  meta.maintainers = with maintainers; [ pacien ];
+}
diff --git a/nixos/modules/services/backup/restic-rest-server.nix b/nixos/modules/services/backup/restic-rest-server.nix
new file mode 100644
index 00000000000..4717119f178
--- /dev/null
+++ b/nixos/modules/services/backup/restic-rest-server.nix
@@ -0,0 +1,111 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.restic.server;
+in
+{
+  meta.maintainers = [ maintainers.bachp ];
+
+  options.services.restic.server = {
+    enable = mkEnableOption "Restic REST Server";
+
+    listenAddress = mkOption {
+      default = ":8000";
+      example = "127.0.0.1:8080";
+      type = types.str;
+      description = "Listen on a specific IP address and port.";
+    };
+
+    dataDir = mkOption {
+      default = "/var/lib/restic";
+      type = types.path;
+      description = "The directory for storing the restic repository.";
+    };
+
+    appendOnly = mkOption {
+      default = false;
+      type = types.bool;
+      description = ''
+        Enable append only mode.
+        This mode allows creation of new backups but prevents deletion and modification of existing backups.
+        This can be useful when backing up systems that have a potential of being hacked.
+      '';
+    };
+
+    privateRepos = mkOption {
+      default = false;
+      type = types.bool;
+      description = ''
+        Enable private repos.
+        Grants access only when a subdirectory with the same name as the user is specified in the repository URL.
+      '';
+    };
+
+    prometheus = mkOption {
+      default = false;
+      type = types.bool;
+      description = "Enable Prometheus metrics at /metrics.";
+    };
+
+    extraFlags = mkOption {
+      type = types.listOf types.str;
+      default = [];
+      description = ''
+        Extra commandline options to pass to Restic REST server.
+      '';
+    };
+
+    package = mkOption {
+      default = pkgs.restic-rest-server;
+      defaultText = literalExpression "pkgs.restic-rest-server";
+      type = types.package;
+      description = "Restic REST server package to use.";
+    };
+  };
+
+  config = mkIf cfg.enable {
+    systemd.services.restic-rest-server = {
+      description = "Restic REST Server";
+      after = [ "network.target" ];
+      wantedBy = [ "multi-user.target" ];
+      serviceConfig = {
+        ExecStart = ''
+          ${cfg.package}/bin/rest-server \
+          --listen ${cfg.listenAddress} \
+          --path ${cfg.dataDir} \
+          ${optionalString cfg.appendOnly "--append-only"} \
+          ${optionalString cfg.privateRepos "--private-repos"} \
+          ${optionalString cfg.prometheus "--prometheus"} \
+          ${escapeShellArgs cfg.extraFlags} \
+        '';
+        Type = "simple";
+        User = "restic";
+        Group = "restic";
+
+        # Security hardening
+        ReadWritePaths = [ cfg.dataDir ];
+        PrivateTmp = true;
+        ProtectSystem = "strict";
+        ProtectKernelTunables = true;
+        ProtectKernelModules = true;
+        ProtectControlGroups = true;
+        PrivateDevices = true;
+      };
+    };
+
+    systemd.tmpfiles.rules = mkIf cfg.privateRepos [
+        "f ${cfg.dataDir}/.htpasswd 0700 restic restic -"
+    ];
+
+    users.users.restic = {
+      group = "restic";
+      home = cfg.dataDir;
+      createHome = true;
+      uid = config.ids.uids.restic;
+    };
+
+    users.groups.restic.gid = config.ids.uids.restic;
+  };
+}
diff --git a/nixos/modules/services/backup/restic.nix b/nixos/modules/services/backup/restic.nix
new file mode 100644
index 00000000000..8ff8e31864b
--- /dev/null
+++ b/nixos/modules/services/backup/restic.nix
@@ -0,0 +1,290 @@
+{ config, lib, pkgs, utils, ... }:
+
+with lib;
+
+let
+  # Type for a valid systemd unit option. Needed for correctly passing "timerConfig" to "systemd.timers"
+  inherit (utils.systemdUtils.unitOptions) unitOption;
+in
+{
+  options.services.restic.backups = mkOption {
+    description = ''
+      Periodic backups to create with Restic.
+    '';
+    type = types.attrsOf (types.submodule ({ config, name, ... }: {
+      options = {
+        passwordFile = mkOption {
+          type = types.str;
+          description = ''
+            Read the repository password from a file.
+          '';
+          example = "/etc/nixos/restic-password";
+        };
+
+        environmentFile = mkOption {
+          type = with types; nullOr str;
+          # added on 2021-08-28, s3CredentialsFile should
+          # be removed in the future (+ remember the warning)
+          default = config.s3CredentialsFile;
+          description = ''
+            file containing the credentials to access the repository, in the
+            format of an EnvironmentFile as described by systemd.exec(5)
+          '';
+        };
+
+        s3CredentialsFile = mkOption {
+          type = with types; nullOr str;
+          default = null;
+          description = ''
+            file containing the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
+            for an S3-hosted repository, in the format of an EnvironmentFile
+            as described by systemd.exec(5)
+          '';
+        };
+
+        rcloneOptions = mkOption {
+          type = with types; nullOr (attrsOf (oneOf [ str bool ]));
+          default = null;
+          description = ''
+            Options to pass to rclone to control its behavior.
+            See <link xlink:href="https://rclone.org/docs/#options"/> for
+            available options. When specifying option names, strip the
+            leading <literal>--</literal>. To set a flag such as
+            <literal>--drive-use-trash</literal>, which does not take a value,
+            set the value to the Boolean <literal>true</literal>.
+          '';
+          example = {
+            bwlimit = "10M";
+            drive-use-trash = "true";
+          };
+        };
+
+        rcloneConfig = mkOption {
+          type = with types; nullOr (attrsOf (oneOf [ str bool ]));
+          default = null;
+          description = ''
+            Configuration for the rclone remote being used for backup.
+            See the remote's specific options under rclone's docs at
+            <link xlink:href="https://rclone.org/docs/"/>. When specifying
+            option names, use the "config" name specified in the docs.
+            For example, to set <literal>--b2-hard-delete</literal> for a B2
+            remote, use <literal>hard_delete = true</literal> in the
+            attribute set.
+            Warning: Secrets set in here will be world-readable in the Nix
+            store! Consider using the <literal>rcloneConfigFile</literal>
+            option instead to specify secret values separately. Note that
+            options set here will override those set in the config file.
+          '';
+          example = {
+            type = "b2";
+            account = "xxx";
+            key = "xxx";
+            hard_delete = true;
+          };
+        };
+
+        rcloneConfigFile = mkOption {
+          type = with types; nullOr path;
+          default = null;
+          description = ''
+            Path to the file containing rclone configuration. This file
+            must contain configuration for the remote specified in this backup
+            set and also must be readable by root. Options set in
+            <literal>rcloneConfig</literal> will override those set in this
+            file.
+          '';
+        };
+
+        repository = mkOption {
+          type = types.str;
+          description = ''
+            repository to backup to.
+          '';
+          example = "sftp:backup@192.168.1.100:/backups/${name}";
+        };
+
+        paths = mkOption {
+          type = types.nullOr (types.listOf types.str);
+          default = null;
+          description = ''
+            Which paths to backup.  If null or an empty array, no
+            backup command will be run.  This can be used to create a
+            prune-only job.
+          '';
+          example = [
+            "/var/lib/postgresql"
+            "/home/user/backup"
+          ];
+        };
+
+        timerConfig = mkOption {
+          type = types.attrsOf unitOption;
+          default = {
+            OnCalendar = "daily";
+          };
+          description = ''
+            When to run the backup. See man systemd.timer for details.
+          '';
+          example = {
+            OnCalendar = "00:05";
+            RandomizedDelaySec = "5h";
+          };
+        };
+
+        user = mkOption {
+          type = types.str;
+          default = "root";
+          description = ''
+            As which user the backup should run.
+          '';
+          example = "postgresql";
+        };
+
+        extraBackupArgs = mkOption {
+          type = types.listOf types.str;
+          default = [];
+          description = ''
+            Extra arguments passed to restic backup.
+          '';
+          example = [
+            "--exclude-file=/etc/nixos/restic-ignore"
+          ];
+        };
+
+        extraOptions = mkOption {
+          type = types.listOf types.str;
+          default = [];
+          description = ''
+            Extra extended options to be passed to the restic --option flag.
+          '';
+          example = [
+            "sftp.command='ssh backup@192.168.1.100 -i /home/user/.ssh/id_rsa -s sftp'"
+          ];
+        };
+
+        initialize = mkOption {
+          type = types.bool;
+          default = false;
+          description = ''
+            Create the repository if it doesn't exist.
+          '';
+        };
+
+        pruneOpts = mkOption {
+          type = types.listOf types.str;
+          default = [];
+          description = ''
+            A list of options (--keep-* et al.) for 'restic forget
+            --prune', to automatically prune old snapshots.  The
+            'forget' command is run *after* the 'backup' command, so
+            keep that in mind when constructing the --keep-* options.
+          '';
+          example = [
+            "--keep-daily 7"
+            "--keep-weekly 5"
+            "--keep-monthly 12"
+            "--keep-yearly 75"
+          ];
+        };
+
+        dynamicFilesFrom = mkOption {
+          type = with types; nullOr str;
+          default = null;
+          description = ''
+            A script that produces a list of files to back up.  The
+            results of this command are given to the '--files-from'
+            option.
+          '';
+          example = "find /home/matt/git -type d -name .git";
+        };
+      };
+    }));
+    default = {};
+    example = {
+      localbackup = {
+        paths = [ "/home" ];
+        repository = "/mnt/backup-hdd";
+        passwordFile = "/etc/nixos/secrets/restic-password";
+        initialize = true;
+      };
+      remotebackup = {
+        paths = [ "/home" ];
+        repository = "sftp:backup@host:/backups/home";
+        passwordFile = "/etc/nixos/secrets/restic-password";
+        extraOptions = [
+          "sftp.command='ssh backup@host -i /etc/nixos/secrets/backup-private-key -s sftp'"
+        ];
+        timerConfig = {
+          OnCalendar = "00:05";
+          RandomizedDelaySec = "5h";
+        };
+      };
+    };
+  };
+
+  config = {
+    warnings = mapAttrsToList (n: v: "services.restic.backups.${n}.s3CredentialsFile is deprecated, please use services.restic.backups.${n}.environmentFile instead.") (filterAttrs (n: v: v.s3CredentialsFile != null) config.services.restic.backups);
+    systemd.services =
+      mapAttrs' (name: backup:
+        let
+          extraOptions = concatMapStrings (arg: " -o ${arg}") backup.extraOptions;
+          resticCmd = "${pkgs.restic}/bin/restic${extraOptions}";
+          filesFromTmpFile = "/run/restic-backups-${name}/includes";
+          backupPaths = if (backup.dynamicFilesFrom == null)
+                        then if (backup.paths != null) then concatStringsSep " " backup.paths else ""
+                        else "--files-from ${filesFromTmpFile}";
+          pruneCmd = optionals (builtins.length backup.pruneOpts > 0) [
+            ( resticCmd + " forget --prune " + (concatStringsSep " " backup.pruneOpts) )
+            ( resticCmd + " check" )
+          ];
+          # Helper functions for rclone remotes
+          rcloneRemoteName = builtins.elemAt (splitString ":" backup.repository) 1;
+          rcloneAttrToOpt = v: "RCLONE_" + toUpper (builtins.replaceStrings [ "-" ] [ "_" ] v);
+          rcloneAttrToConf = v: "RCLONE_CONFIG_" + toUpper (rcloneRemoteName + "_" + v);
+          toRcloneVal = v: if lib.isBool v then lib.boolToString v else v;
+        in nameValuePair "restic-backups-${name}" ({
+          environment = {
+            RESTIC_PASSWORD_FILE = backup.passwordFile;
+            RESTIC_REPOSITORY = backup.repository;
+          } // optionalAttrs (backup.rcloneOptions != null) (mapAttrs' (name: value:
+            nameValuePair (rcloneAttrToOpt name) (toRcloneVal value)
+          ) backup.rcloneOptions) // optionalAttrs (backup.rcloneConfigFile != null) {
+            RCLONE_CONFIG = backup.rcloneConfigFile;
+          } // optionalAttrs (backup.rcloneConfig != null) (mapAttrs' (name: value:
+            nameValuePair (rcloneAttrToConf name) (toRcloneVal value)
+          ) backup.rcloneConfig);
+          path = [ pkgs.openssh ];
+          restartIfChanged = false;
+          serviceConfig = {
+            Type = "oneshot";
+            ExecStart = (optionals (backupPaths != "") [ "${resticCmd} backup --cache-dir=%C/restic-backups-${name} ${concatStringsSep " " backup.extraBackupArgs} ${backupPaths}" ])
+                        ++ pruneCmd;
+            User = backup.user;
+            RuntimeDirectory = "restic-backups-${name}";
+            CacheDirectory = "restic-backups-${name}";
+            CacheDirectoryMode = "0700";
+          } // optionalAttrs (backup.environmentFile != null) {
+            EnvironmentFile = backup.environmentFile;
+          };
+        } // optionalAttrs (backup.initialize || backup.dynamicFilesFrom != null) {
+          preStart = ''
+            ${optionalString (backup.initialize) ''
+              ${resticCmd} snapshots || ${resticCmd} init
+            ''}
+            ${optionalString (backup.dynamicFilesFrom != null) ''
+              ${pkgs.writeScript "dynamicFilesFromScript" backup.dynamicFilesFrom} > ${filesFromTmpFile}
+            ''}
+          '';
+        } // optionalAttrs (backup.dynamicFilesFrom != null) {
+          postStart = ''
+            rm ${filesFromTmpFile}
+          '';
+        })
+      ) config.services.restic.backups;
+    systemd.timers =
+      mapAttrs' (name: backup: nameValuePair "restic-backups-${name}" {
+        wantedBy = [ "timers.target" ];
+        timerConfig = backup.timerConfig;
+      }) config.services.restic.backups;
+  };
+}
diff --git a/nixos/modules/services/backup/rsnapshot.nix b/nixos/modules/services/backup/rsnapshot.nix
new file mode 100644
index 00000000000..6635a51ec2c
--- /dev/null
+++ b/nixos/modules/services/backup/rsnapshot.nix
@@ -0,0 +1,75 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.rsnapshot;
+  cfgfile = pkgs.writeText "rsnapshot.conf" ''
+    config_version	1.2
+    cmd_cp	${pkgs.coreutils}/bin/cp
+    cmd_rm	${pkgs.coreutils}/bin/rm
+    cmd_rsync	${pkgs.rsync}/bin/rsync
+    cmd_ssh	${pkgs.openssh}/bin/ssh
+    cmd_logger	${pkgs.inetutils}/bin/logger
+    cmd_du	${pkgs.coreutils}/bin/du
+    cmd_rsnapshot_diff	${pkgs.rsnapshot}/bin/rsnapshot-diff
+    lockfile	/run/rsnapshot.pid
+    link_dest	1
+
+    ${cfg.extraConfig}
+  '';
+in
+{
+  options = {
+    services.rsnapshot = {
+      enable = mkEnableOption "rsnapshot backups";
+      enableManualRsnapshot = mkOption {
+        description = "Whether to enable manual usage of the rsnapshot command with this module.";
+        default = true;
+        type = types.bool;
+      };
+
+      extraConfig = mkOption {
+        default = "";
+        example = ''
+          retains	hourly	24
+          retain	daily	365
+          backup	/home/	localhost/
+        '';
+        type = types.lines;
+        description = ''
+          rsnapshot configuration option in addition to the defaults from
+          rsnapshot and this module.
+
+          Note that tabs are required to separate option arguments, and
+          directory names require trailing slashes.
+
+          The "extra" in the option name might be a little misleading right
+          now, as it is required to get a functional configuration.
+        '';
+      };
+
+      cronIntervals = mkOption {
+        default = {};
+        example = { hourly = "0 * * * *"; daily = "50 21 * * *"; };
+        type = types.attrsOf types.str;
+        description = ''
+          Periodicity at which intervals should be run by cron.
+          Note that the intervals also have to exist in configuration
+          as retain options.
+        '';
+      };
+    };
+  };
+
+  config = mkIf cfg.enable (mkMerge [
+    {
+      services.cron.systemCronJobs =
+        mapAttrsToList (interval: time: "${time} root ${pkgs.rsnapshot}/bin/rsnapshot -c ${cfgfile} ${interval}") cfg.cronIntervals;
+    }
+    (mkIf cfg.enableManualRsnapshot {
+      environment.systemPackages = [ pkgs.rsnapshot ];
+      environment.etc."rsnapshot.conf".source = cfgfile;
+    })
+  ]);
+}
diff --git a/nixos/modules/services/backup/sanoid.nix b/nixos/modules/services/backup/sanoid.nix
new file mode 100644
index 00000000000..5eb031b2e9f
--- /dev/null
+++ b/nixos/modules/services/backup/sanoid.nix
@@ -0,0 +1,204 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.sanoid;
+
+  datasetSettingsType = with types;
+    (attrsOf (nullOr (oneOf [ str int bool (listOf str) ]))) // {
+      description = "dataset/template options";
+    };
+
+  commonOptions = {
+    hourly = mkOption {
+      description = "Number of hourly snapshots.";
+      type = with types; nullOr ints.unsigned;
+      default = null;
+    };
+
+    daily = mkOption {
+      description = "Number of daily snapshots.";
+      type = with types; nullOr ints.unsigned;
+      default = null;
+    };
+
+    monthly = mkOption {
+      description = "Number of monthly snapshots.";
+      type = with types; nullOr ints.unsigned;
+      default = null;
+    };
+
+    yearly = mkOption {
+      description = "Number of yearly snapshots.";
+      type = with types; nullOr ints.unsigned;
+      default = null;
+    };
+
+    autoprune = mkOption {
+      description = "Whether to automatically prune old snapshots.";
+      type = with types; nullOr bool;
+      default = null;
+    };
+
+    autosnap = mkOption {
+      description = "Whether to automatically take snapshots.";
+      type = with types; nullOr bool;
+      default = null;
+    };
+  };
+
+  datasetOptions = rec {
+    use_template = mkOption {
+      description = "Names of the templates to use for this dataset.";
+      type = types.listOf (types.str // {
+        check = (types.enum (attrNames cfg.templates)).check;
+        description = "configured template name";
+      });
+      default = [ ];
+    };
+    useTemplate = use_template;
+
+    recursive = mkOption {
+      description = ''
+        Whether to recursively snapshot dataset children.
+        You can also set this to <literal>"zfs"</literal> to handle datasets
+        recursively in an atomic way without the possibility to
+        override settings for child datasets.
+      '';
+      type = with types; oneOf [ bool (enum [ "zfs" ]) ];
+      default = false;
+    };
+
+    process_children_only = mkOption {
+      description = "Whether to only snapshot child datasets if recursing.";
+      type = types.bool;
+      default = false;
+    };
+    processChildrenOnly = process_children_only;
+  };
+
+  # Extract unique dataset names
+  datasets = unique (attrNames cfg.datasets);
+
+  # Function to build "zfs allow" and "zfs unallow" commands for the
+  # filesystems we've delegated permissions to.
+  buildAllowCommand = zfsAction: permissions: dataset: lib.escapeShellArgs [
+    # Here we explicitly use the booted system to guarantee the stable API needed by ZFS
+    "-+/run/booted-system/sw/bin/zfs"
+    zfsAction
+    "sanoid"
+    (concatStringsSep "," permissions)
+    dataset
+  ];
+
+  configFile =
+    let
+      mkValueString = v:
+        if builtins.isList v then concatStringsSep "," v
+        else generators.mkValueStringDefault { } v;
+
+      mkKeyValue = k: v:
+        if v == null then ""
+        else if k == "processChildrenOnly" then ""
+        else if k == "useTemplate" then ""
+        else generators.mkKeyValueDefault { inherit mkValueString; } "=" k v;
+    in
+    generators.toINI { inherit mkKeyValue; } cfg.settings;
+
+in
+{
+
+  # Interface
+
+  options.services.sanoid = {
+    enable = mkEnableOption "Sanoid ZFS snapshotting service";
+
+    interval = mkOption {
+      type = types.str;
+      default = "hourly";
+      example = "daily";
+      description = ''
+        Run sanoid at this interval. The default is to run hourly.
+
+        The format is described in
+        <citerefentry><refentrytitle>systemd.time</refentrytitle>
+        <manvolnum>7</manvolnum></citerefentry>.
+      '';
+    };
+
+    datasets = mkOption {
+      type = types.attrsOf (types.submodule ({ config, options, ... }: {
+        freeformType = datasetSettingsType;
+        options = commonOptions // datasetOptions;
+        config.use_template = mkAliasDefinitions (mkDefault options.useTemplate or { });
+        config.process_children_only = mkAliasDefinitions (mkDefault options.processChildrenOnly or { });
+      }));
+      default = { };
+      description = "Datasets to snapshot.";
+    };
+
+    templates = mkOption {
+      type = types.attrsOf (types.submodule {
+        freeformType = datasetSettingsType;
+        options = commonOptions;
+      });
+      default = { };
+      description = "Templates for datasets.";
+    };
+
+    settings = mkOption {
+      type = types.attrsOf datasetSettingsType;
+      description = ''
+        Free-form settings written directly to the config file. See
+        <link xlink:href="https://github.com/jimsalterjrs/sanoid/blob/master/sanoid.defaults.conf"/>
+        for allowed values.
+      '';
+    };
+
+    extraArgs = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = [ "--verbose" "--readonly" "--debug" ];
+      description = ''
+        Extra arguments to pass to sanoid. See
+        <link xlink:href="https://github.com/jimsalterjrs/sanoid/#sanoid-command-line-options"/>
+        for allowed options.
+      '';
+    };
+  };
+
+  # Implementation
+
+  config = mkIf cfg.enable {
+    services.sanoid.settings = mkMerge [
+      (mapAttrs' (d: v: nameValuePair ("template_" + d) v) cfg.templates)
+      (mapAttrs (d: v: v) cfg.datasets)
+    ];
+
+    systemd.services.sanoid = {
+      description = "Sanoid snapshot service";
+      serviceConfig = {
+        ExecStartPre = (map (buildAllowCommand "allow" [ "snapshot" "mount" "destroy" ]) datasets);
+        ExecStopPost = (map (buildAllowCommand "unallow" [ "snapshot" "mount" "destroy" ]) datasets);
+        ExecStart = lib.escapeShellArgs ([
+          "${pkgs.sanoid}/bin/sanoid"
+          "--cron"
+          "--configdir"
+          (pkgs.writeTextDir "sanoid.conf" configFile)
+        ] ++ cfg.extraArgs);
+        User = "sanoid";
+        Group = "sanoid";
+        DynamicUser = true;
+        RuntimeDirectory = "sanoid";
+        CacheDirectory = "sanoid";
+      };
+      # Prevents missing snapshots during DST changes
+      environment.TZ = "UTC";
+      after = [ "zfs.target" ];
+      startAt = cfg.interval;
+    };
+  };
+
+  meta.maintainers = with maintainers; [ lopsided98 ];
+}
diff --git a/nixos/modules/services/backup/syncoid.nix b/nixos/modules/services/backup/syncoid.nix
new file mode 100644
index 00000000000..4df10f5ee02
--- /dev/null
+++ b/nixos/modules/services/backup/syncoid.nix
@@ -0,0 +1,421 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+  cfg = config.services.syncoid;
+
+  # Extract local dasaset names (so no datasets containing "@")
+  localDatasetName = d: optionals (d != null) (
+    let m = builtins.match "([^/@]+[^@]*)" d; in
+    optionals (m != null) m
+  );
+
+  # Escape as required by: https://www.freedesktop.org/software/systemd/man/systemd.unit.html
+  escapeUnitName = name:
+    lib.concatMapStrings (s: if lib.isList s then "-" else s)
+      (builtins.split "[^a-zA-Z0-9_.\\-]+" name);
+
+  # Function to build "zfs allow" commands for the filesystems we've
+  # delegated permissions to. It also checks if the target dataset
+  # exists before delegating permissions, if it doesn't exist we
+  # delegate it to the parent dataset. This should solve the case of
+  # provisoning new datasets.
+  buildAllowCommand = permissions: dataset: (
+    "-+${pkgs.writeShellScript "zfs-allow-${dataset}" ''
+      # Here we explicitly use the booted system to guarantee the stable API needed by ZFS
+
+      # Run a ZFS list on the dataset to check if it exists
+      if ${lib.escapeShellArgs [
+        "/run/booted-system/sw/bin/zfs"
+        "list"
+        dataset
+      ]} 2> /dev/null; then
+        ${lib.escapeShellArgs [
+          "/run/booted-system/sw/bin/zfs"
+          "allow"
+          cfg.user
+          (concatStringsSep "," permissions)
+          dataset
+        ]}
+      else
+        ${lib.escapeShellArgs [
+          "/run/booted-system/sw/bin/zfs"
+          "allow"
+          cfg.user
+          (concatStringsSep "," permissions)
+          # Remove the last part of the path
+          (builtins.dirOf dataset)
+        ]}
+      fi
+    ''}"
+  );
+
+  # Function to build "zfs unallow" commands for the filesystems we've
+  # delegated permissions to. Here we unallow both the target but also
+  # on the parent dataset because at this stage we have no way of
+  # knowing if the allow command did execute on the parent dataset or
+  # not in the pre-hook. We can't run the same if in the post hook
+  # since the dataset should have been created at this point.
+  buildUnallowCommand = permissions: dataset: (
+    "-+${pkgs.writeShellScript "zfs-unallow-${dataset}" ''
+      # Here we explicitly use the booted system to guarantee the stable API needed by ZFS
+      ${lib.escapeShellArgs [
+        "/run/booted-system/sw/bin/zfs"
+        "unallow"
+        cfg.user
+        (concatStringsSep "," permissions)
+        dataset
+      ]}
+      ${lib.escapeShellArgs [
+        "/run/booted-system/sw/bin/zfs"
+        "unallow"
+        cfg.user
+        (concatStringsSep "," permissions)
+        # Remove the last part of the path
+        (builtins.dirOf dataset)
+      ]}
+    ''}"
+  );
+in
+{
+
+  # Interface
+
+  options.services.syncoid = {
+    enable = mkEnableOption "Syncoid ZFS synchronization service";
+
+    interval = mkOption {
+      type = types.str;
+      default = "hourly";
+      example = "*-*-* *:15:00";
+      description = ''
+        Run syncoid at this interval. The default is to run hourly.
+
+        The format is described in
+        <citerefentry><refentrytitle>systemd.time</refentrytitle>
+        <manvolnum>7</manvolnum></citerefentry>.
+      '';
+    };
+
+    user = mkOption {
+      type = types.str;
+      default = "syncoid";
+      example = "backup";
+      description = ''
+        The user for the service. ZFS privilege delegation will be
+        automatically configured for any local pools used by syncoid if this
+        option is set to a user other than root. The user will be given the
+        "hold" and "send" privileges on any pool that has datasets being sent
+        and the "create", "mount", "receive", and "rollback" privileges on
+        any pool that has datasets being received.
+      '';
+    };
+
+    group = mkOption {
+      type = types.str;
+      default = "syncoid";
+      example = "backup";
+      description = "The group for the service.";
+    };
+
+    sshKey = mkOption {
+      type = types.nullOr types.path;
+      # Prevent key from being copied to store
+      apply = mapNullable toString;
+      default = null;
+      description = ''
+        SSH private key file to use to login to the remote system. Can be
+        overridden in individual commands.
+      '';
+    };
+
+    localSourceAllow = mkOption {
+      type = types.listOf types.str;
+      # Permissions snapshot and destroy are in case --no-sync-snap is not used
+      default = [ "bookmark" "hold" "send" "snapshot" "destroy" ];
+      description = ''
+        Permissions granted for the <option>services.syncoid.user</option> user
+        for local source datasets. See
+        <link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
+        for available permissions.
+      '';
+    };
+
+    localTargetAllow = mkOption {
+      type = types.listOf types.str;
+      default = [ "change-key" "compression" "create" "mount" "mountpoint" "receive" "rollback" ];
+      example = [ "create" "mount" "receive" "rollback" ];
+      description = ''
+        Permissions granted for the <option>services.syncoid.user</option> user
+        for local target datasets. See
+        <link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
+        for available permissions.
+        Make sure to include the <literal>change-key</literal> permission if you send raw encrypted datasets,
+        the <literal>compression</literal> permission if you send raw compressed datasets, and so on.
+        For remote target datasets you'll have to set your remote user permissions by yourself.
+      '';
+    };
+
+    commonArgs = mkOption {
+      type = types.listOf types.str;
+      default = [ ];
+      example = [ "--no-sync-snap" ];
+      description = ''
+        Arguments to add to every syncoid command, unless disabled for that
+        command. See
+        <link xlink:href="https://github.com/jimsalterjrs/sanoid/#syncoid-command-line-options"/>
+        for available options.
+      '';
+    };
+
+    service = mkOption {
+      type = types.attrs;
+      default = { };
+      description = ''
+        Systemd configuration common to all syncoid services.
+      '';
+    };
+
+    commands = mkOption {
+      type = types.attrsOf (types.submodule ({ name, ... }: {
+        options = {
+          source = mkOption {
+            type = types.str;
+            example = "pool/dataset";
+            description = ''
+              Source ZFS dataset. Can be either local or remote. Defaults to
+              the attribute name.
+            '';
+          };
+
+          target = mkOption {
+            type = types.str;
+            example = "user@server:pool/dataset";
+            description = ''
+              Target ZFS dataset. Can be either local
+              (<replaceable>pool/dataset</replaceable>) or remote
+              (<replaceable>user@server:pool/dataset</replaceable>).
+            '';
+          };
+
+          recursive = mkEnableOption ''the transfer of child datasets'';
+
+          sshKey = mkOption {
+            type = types.nullOr types.path;
+            # Prevent key from being copied to store
+            apply = mapNullable toString;
+            description = ''
+              SSH private key file to use to login to the remote system.
+              Defaults to <option>services.syncoid.sshKey</option> option.
+            '';
+          };
+
+          localSourceAllow = mkOption {
+            type = types.listOf types.str;
+            description = ''
+              Permissions granted for the <option>services.syncoid.user</option> user
+              for local source datasets. See
+              <link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
+              for available permissions.
+              Defaults to <option>services.syncoid.localSourceAllow</option> option.
+            '';
+          };
+
+          localTargetAllow = mkOption {
+            type = types.listOf types.str;
+            description = ''
+              Permissions granted for the <option>services.syncoid.user</option> user
+              for local target datasets. See
+              <link xlink:href="https://openzfs.github.io/openzfs-docs/man/8/zfs-allow.8.html"/>
+              for available permissions.
+              Make sure to include the <literal>change-key</literal> permission if you send raw encrypted datasets,
+              the <literal>compression</literal> permission if you send raw compressed datasets, and so on.
+              For remote target datasets you'll have to set your remote user permissions by yourself.
+            '';
+          };
+
+          sendOptions = mkOption {
+            type = types.separatedString " ";
+            default = "";
+            example = "Lc e";
+            description = ''
+              Advanced options to pass to zfs send. Options are specified
+              without their leading dashes and separated by spaces.
+            '';
+          };
+
+          recvOptions = mkOption {
+            type = types.separatedString " ";
+            default = "";
+            example = "ux recordsize o compression=lz4";
+            description = ''
+              Advanced options to pass to zfs recv. Options are specified
+              without their leading dashes and separated by spaces.
+            '';
+          };
+
+          useCommonArgs = mkOption {
+            type = types.bool;
+            default = true;
+            description = ''
+              Whether to add the configured common arguments to this command.
+            '';
+          };
+
+          service = mkOption {
+            type = types.attrs;
+            default = { };
+            description = ''
+              Systemd configuration specific to this syncoid service.
+            '';
+          };
+
+          extraArgs = mkOption {
+            type = types.listOf types.str;
+            default = [ ];
+            example = [ "--sshport 2222" ];
+            description = "Extra syncoid arguments for this command.";
+          };
+        };
+        config = {
+          source = mkDefault name;
+          sshKey = mkDefault cfg.sshKey;
+          localSourceAllow = mkDefault cfg.localSourceAllow;
+          localTargetAllow = mkDefault cfg.localTargetAllow;
+        };
+      }));
+      default = { };
+      example = literalExpression ''
+        {
+          "pool/test".target = "root@target:pool/test";
+        }
+      '';
+      description = "Syncoid commands to run.";
+    };
+  };
+
+  # Implementation
+
+  config = mkIf cfg.enable {
+    users = {
+      users = mkIf (cfg.user == "syncoid") {
+        syncoid = {
+          group = cfg.group;
+          isSystemUser = true;
+          # For syncoid to be able to create /var/lib/syncoid/.ssh/
+          # and to use custom ssh_config or known_hosts.
+          home = "/var/lib/syncoid";
+          createHome = false;
+        };
+      };
+      groups = mkIf (cfg.group == "syncoid") {
+        syncoid = { };
+      };
+    };
+
+    systemd.services = mapAttrs'
+      (name: c:
+        nameValuePair "syncoid-${escapeUnitName name}" (mkMerge [
+          {
+            description = "Syncoid ZFS synchronization from ${c.source} to ${c.target}";
+            after = [ "zfs.target" ];
+            startAt = cfg.interval;
+            # syncoid may need zpool to get feature@extensible_dataset
+            path = [ "/run/booted-system/sw/bin/" ];
+            serviceConfig = {
+              ExecStartPre =
+                (map (buildAllowCommand c.localSourceAllow) (localDatasetName c.source)) ++
+                (map (buildAllowCommand c.localTargetAllow) (localDatasetName c.target));
+              ExecStopPost =
+                (map (buildUnallowCommand c.localSourceAllow) (localDatasetName c.source)) ++
+                (map (buildUnallowCommand c.localTargetAllow) (localDatasetName c.target));
+              ExecStart = lib.escapeShellArgs ([ "${pkgs.sanoid}/bin/syncoid" ]
+                ++ optionals c.useCommonArgs cfg.commonArgs
+                ++ optional c.recursive "-r"
+                ++ optionals (c.sshKey != null) [ "--sshkey" c.sshKey ]
+                ++ c.extraArgs
+                ++ [
+                "--sendoptions"
+                c.sendOptions
+                "--recvoptions"
+                c.recvOptions
+                "--no-privilege-elevation"
+                c.source
+                c.target
+              ]);
+              User = cfg.user;
+              Group = cfg.group;
+              StateDirectory = [ "syncoid" ];
+              StateDirectoryMode = "700";
+              # Prevent SSH control sockets of different syncoid services from interfering
+              PrivateTmp = true;
+              # Permissive access to /proc because syncoid
+              # calls ps(1) to detect ongoing `zfs receive`.
+              ProcSubset = "all";
+              ProtectProc = "default";
+
+              # The following options are only for optimizing:
+              # systemd-analyze security | grep syncoid-'*'
+              AmbientCapabilities = "";
+              CapabilityBoundingSet = "";
+              DeviceAllow = [ "/dev/zfs" ];
+              LockPersonality = true;
+              MemoryDenyWriteExecute = true;
+              NoNewPrivileges = true;
+              PrivateDevices = true;
+              PrivateMounts = true;
+              PrivateNetwork = mkDefault false;
+              PrivateUsers = true;
+              ProtectClock = true;
+              ProtectControlGroups = true;
+              ProtectHome = true;
+              ProtectHostname = true;
+              ProtectKernelLogs = true;
+              ProtectKernelModules = true;
+              ProtectKernelTunables = true;
+              ProtectSystem = "strict";
+              RemoveIPC = true;
+              RestrictAddressFamilies = [ "AF_UNIX" "AF_INET" "AF_INET6" ];
+              RestrictNamespaces = true;
+              RestrictRealtime = true;
+              RestrictSUIDSGID = true;
+              RootDirectory = "/run/syncoid/${escapeUnitName name}";
+              RootDirectoryStartOnly = true;
+              BindPaths = [ "/dev/zfs" ];
+              BindReadOnlyPaths = [ builtins.storeDir "/etc" "/run" "/bin/sh" ];
+              # Avoid useless mounting of RootDirectory= in the own RootDirectory= of ExecStart='s mount namespace.
+              InaccessiblePaths = [ "-+/run/syncoid/${escapeUnitName name}" ];
+              MountAPIVFS = true;
+              # Create RootDirectory= in the host's mount namespace.
+              RuntimeDirectory = [ "syncoid/${escapeUnitName name}" ];
+              RuntimeDirectoryMode = "700";
+              SystemCallFilter = [
+                "@system-service"
+                # Groups in @system-service which do not contain a syscall listed by:
+                # perf stat -x, 2>perf.log -e 'syscalls:sys_enter_*' syncoid …
+                # awk >perf.syscalls -F "," '$1 > 0 {sub("syscalls:sys_enter_","",$3); print $3}' perf.log
+                # systemd-analyze syscall-filter | grep -v -e '#' | sed -e ':loop; /^[^ ]/N; s/\n //; t loop' | grep $(printf ' -e \\<%s\\>' $(cat perf.syscalls)) | cut -f 1 -d ' '
+                "~@aio"
+                "~@chown"
+                "~@keyring"
+                "~@memlock"
+                "~@privileged"
+                "~@resources"
+                "~@setuid"
+                "~@timer"
+              ];
+              SystemCallArchitectures = "native";
+              # This is for BindPaths= and BindReadOnlyPaths=
+              # to allow traversal of directories they create in RootDirectory=.
+              UMask = "0066";
+            };
+          }
+          cfg.service
+          c.service
+        ]))
+      cfg.commands;
+  };
+
+  meta.maintainers = with maintainers; [ julm lopsided98 ];
+}
diff --git a/nixos/modules/services/backup/tarsnap.nix b/nixos/modules/services/backup/tarsnap.nix
new file mode 100644
index 00000000000..9b5fd90012e
--- /dev/null
+++ b/nixos/modules/services/backup/tarsnap.nix
@@ -0,0 +1,408 @@
+{ config, lib, options, pkgs, utils, ... }:
+
+with lib;
+
+let
+  gcfg = config.services.tarsnap;
+  opt = options.services.tarsnap;
+
+  configFile = name: cfg: ''
+    keyfile ${cfg.keyfile}
+    ${optionalString (cfg.cachedir != null) "cachedir ${cfg.cachedir}"}
+    ${optionalString cfg.nodump "nodump"}
+    ${optionalString cfg.printStats "print-stats"}
+    ${optionalString cfg.printStats "humanize-numbers"}
+    ${optionalString (cfg.checkpointBytes != null) ("checkpoint-bytes "+cfg.checkpointBytes)}
+    ${optionalString cfg.aggressiveNetworking "aggressive-networking"}
+    ${concatStringsSep "\n" (map (v: "exclude ${v}") cfg.excludes)}
+    ${concatStringsSep "\n" (map (v: "include ${v}") cfg.includes)}
+    ${optionalString cfg.lowmem "lowmem"}
+    ${optionalString cfg.verylowmem "verylowmem"}
+    ${optionalString (cfg.maxbw != null) "maxbw ${toString cfg.maxbw}"}
+    ${optionalString (cfg.maxbwRateUp != null) "maxbw-rate-up ${toString cfg.maxbwRateUp}"}
+    ${optionalString (cfg.maxbwRateDown != null) "maxbw-rate-down ${toString cfg.maxbwRateDown}"}
+  '';
+in
+{
+  imports = [
+    (mkRemovedOptionModule [ "services" "tarsnap" "cachedir" ] "Use services.tarsnap.archives.<name>.cachedir")
+  ];
+
+  options = {
+    services.tarsnap = {
+      enable = mkEnableOption "periodic tarsnap backups";
+
+      keyfile = mkOption {
+        type = types.str;
+        default = "/root/tarsnap.key";
+        description = ''
+          The keyfile which associates this machine with your tarsnap
+          account.
+          Create the keyfile with <command>tarsnap-keygen</command>.
+
+          Note that each individual archive (specified below) may also have its
+          own individual keyfile specified. Tarsnap does not allow multiple
+          concurrent backups with the same cache directory and key (starting a
+          new backup will cause another one to fail). If you have multiple
+          archives specified, you should either spread out your backups to be
+          far apart, or specify a separate key for each archive. By default
+          every archive defaults to using
+          <literal>"/root/tarsnap.key"</literal>.
+
+          It's recommended for backups that you generate a key for every archive
+          using <literal>tarsnap-keygen(1)</literal>, and then generate a
+          write-only tarsnap key using <literal>tarsnap-keymgmt(1)</literal>,
+          and keep your master key(s) for a particular machine off-site.
+
+          The keyfile name should be given as a string and not a path, to
+          avoid the key being copied into the Nix store.
+        '';
+      };
+
+      archives = mkOption {
+        type = types.attrsOf (types.submodule ({ config, options, ... }:
+          {
+            options = {
+              keyfile = mkOption {
+                type = types.str;
+                default = gcfg.keyfile;
+                defaultText = literalExpression "config.${opt.keyfile}";
+                description = ''
+                  Set a specific keyfile for this archive. This defaults to
+                  <literal>"/root/tarsnap.key"</literal> if left unspecified.
+
+                  Use this option if you want to run multiple backups
+                  concurrently - each archive must have a unique key. You can
+                  generate a write-only key derived from your master key (which
+                  is recommended) using <literal>tarsnap-keymgmt(1)</literal>.
+
+                  Note: every archive must have an individual master key. You
+                  must generate multiple keys with
+                  <literal>tarsnap-keygen(1)</literal>, and then generate write
+                  only keys from those.
+
+                  The keyfile name should be given as a string and not a path, to
+                  avoid the key being copied into the Nix store.
+                '';
+              };
+
+              cachedir = mkOption {
+                type = types.nullOr types.path;
+                default = "/var/cache/tarsnap/${utils.escapeSystemdPath config.keyfile}";
+                defaultText = literalExpression ''
+                  "/var/cache/tarsnap/''${utils.escapeSystemdPath config.${options.keyfile}}"
+                '';
+                description = ''
+                  The cache allows tarsnap to identify previously stored data
+                  blocks, reducing archival time and bandwidth usage.
+
+                  Should the cache become desynchronized or corrupted, tarsnap
+                  will refuse to run until you manually rebuild the cache with
+                  <command>tarsnap --fsck</command>.
+
+                  Set to <literal>null</literal> to disable caching.
+                '';
+              };
+
+              nodump = mkOption {
+                type = types.bool;
+                default = true;
+                description = ''
+                  Exclude files with the <literal>nodump</literal> flag.
+                '';
+              };
+
+              printStats = mkOption {
+                type = types.bool;
+                default = true;
+                description = ''
+                  Print global archive statistics upon completion.
+                  The output is available via
+                  <command>systemctl status tarsnap-archive-name</command>.
+                '';
+              };
+
+              checkpointBytes = mkOption {
+                type = types.nullOr types.str;
+                default = "1GB";
+                description = ''
+                  Create a checkpoint every <literal>checkpointBytes</literal>
+                  of uploaded data (optionally specified using an SI prefix).
+
+                  1GB is the minimum value. A higher value is recommended,
+                  as checkpointing is expensive.
+
+                  Set to <literal>null</literal> to disable checkpointing.
+                '';
+              };
+
+              period = mkOption {
+                type = types.str;
+                default = "01:15";
+                example = "hourly";
+                description = ''
+                  Create archive at this interval.
+
+                  The format is described in
+                  <citerefentry><refentrytitle>systemd.time</refentrytitle>
+                  <manvolnum>7</manvolnum></citerefentry>.
+                '';
+              };
+
+              aggressiveNetworking = mkOption {
+                type = types.bool;
+                default = false;
+                description = ''
+                  Upload data over multiple TCP connections, potentially
+                  increasing tarsnap's bandwidth utilisation at the cost
+                  of slowing down all other network traffic. Not
+                  recommended unless TCP congestion is the dominant
+                  limiting factor.
+                '';
+              };
+
+              directories = mkOption {
+                type = types.listOf types.path;
+                default = [];
+                description = "List of filesystem paths to archive.";
+              };
+
+              excludes = mkOption {
+                type = types.listOf types.str;
+                default = [];
+                description = ''
+                  Exclude files and directories matching these patterns.
+                '';
+              };
+
+              includes = mkOption {
+                type = types.listOf types.str;
+                default = [];
+                description = ''
+                  Include only files and directories matching these
+                  patterns (the empty list includes everything).
+
+                  Exclusions have precedence over inclusions.
+                '';
+              };
+
+              lowmem = mkOption {
+                type = types.bool;
+                default = false;
+                description = ''
+                  Reduce memory consumption by not caching small files.
+                  Possibly beneficial if the average file size is smaller
+                  than 1 MB and the number of files is lower than the
+                  total amount of RAM in KB.
+                '';
+              };
+
+              verylowmem = mkOption {
+                type = types.bool;
+                default = false;
+                description = ''
+                  Reduce memory consumption by a factor of 2 beyond what
+                  <literal>lowmem</literal> does, at the cost of significantly
+                  slowing down the archiving process.
+                '';
+              };
+
+              maxbw = mkOption {
+                type = types.nullOr types.int;
+                default = null;
+                description = ''
+                  Abort archival if upstream bandwidth usage in bytes
+                  exceeds this threshold.
+                '';
+              };
+
+              maxbwRateUp = mkOption {
+                type = types.nullOr types.int;
+                default = null;
+                example = literalExpression "25 * 1000";
+                description = ''
+                  Upload bandwidth rate limit in bytes.
+                '';
+              };
+
+              maxbwRateDown = mkOption {
+                type = types.nullOr types.int;
+                default = null;
+                example = literalExpression "50 * 1000";
+                description = ''
+                  Download bandwidth rate limit in bytes.
+                '';
+              };
+
+              verbose = mkOption {
+                type = types.bool;
+                default = false;
+                description = ''
+                  Whether to produce verbose logging output.
+                '';
+              };
+              explicitSymlinks = mkOption {
+                type = types.bool;
+                default = false;
+                description = ''
+                  Whether to follow symlinks specified as archives.
+                '';
+              };
+              followSymlinks = mkOption {
+                type = types.bool;
+                default = false;
+                description = ''
+                  Whether to follow all symlinks in archive trees.
+                '';
+              };
+            };
+          }
+        ));
+
+        default = {};
+
+        example = literalExpression ''
+          {
+            nixos =
+              { directories = [ "/home" "/root/ssl" ];
+              };
+
+            gamedata =
+              { directories = [ "/var/lib/minecraft" ];
+                period      = "*:30";
+              };
+          }
+        '';
+
+        description = ''
+          Tarsnap archive configurations. Each attribute names an archive
+          to be created at a given time interval, according to the options
+          associated with it. When uploading to the tarsnap server,
+          archive names are suffixed by a 1 second resolution timestamp,
+          with the format <literal>%Y%m%d%H%M%S</literal>.
+
+          For each member of the set is created a timer which triggers the
+          instanced <literal>tarsnap-archive-name</literal> service unit. You may use
+          <command>systemctl start tarsnap-archive-name</command> to
+          manually trigger creation of <literal>archive-name</literal> at
+          any time.
+        '';
+      };
+    };
+  };
+
+  config = mkIf gcfg.enable {
+    assertions =
+      (mapAttrsToList (name: cfg:
+        { assertion = cfg.directories != [];
+          message = "Must specify paths for tarsnap to back up";
+        }) gcfg.archives) ++
+      (mapAttrsToList (name: cfg:
+        { assertion = !(cfg.lowmem && cfg.verylowmem);
+          message = "You cannot set both lowmem and verylowmem";
+        }) gcfg.archives);
+
+    systemd.services =
+      (mapAttrs' (name: cfg: nameValuePair "tarsnap-${name}" {
+        description = "Tarsnap archive '${name}'";
+        requires    = [ "network-online.target" ];
+        after       = [ "network-online.target" ];
+
+        path = with pkgs; [ iputils tarsnap util-linux ];
+
+        # In order for the persistent tarsnap timer to work reliably, we have to
+        # make sure that the tarsnap server is reachable after systemd starts up
+        # the service - therefore we sleep in a loop until we can ping the
+        # endpoint.
+        preStart = ''
+          while ! ping -4 -q -c 1 v1-0-0-server.tarsnap.com &> /dev/null; do sleep 3; done
+        '';
+
+        script = let
+          tarsnap = ''tarsnap --configfile "/etc/tarsnap/${name}.conf"'';
+          run = ''${tarsnap} -c -f "${name}-$(date +"%Y%m%d%H%M%S")" \
+                        ${optionalString cfg.verbose "-v"} \
+                        ${optionalString cfg.explicitSymlinks "-H"} \
+                        ${optionalString cfg.followSymlinks "-L"} \
+                        ${concatStringsSep " " cfg.directories}'';
+          cachedir = escapeShellArg cfg.cachedir;
+          in if (cfg.cachedir != null) then ''
+            mkdir -p ${cachedir}
+            chmod 0700 ${cachedir}
+
+            ( flock 9
+              if [ ! -e ${cachedir}/firstrun ]; then
+                ( flock 10
+                  flock -u 9
+                  ${tarsnap} --fsck
+                  flock 9
+                ) 10>${cachedir}/firstrun
+              fi
+            ) 9>${cachedir}/lockf
+
+             exec flock ${cachedir}/firstrun ${run}
+          '' else "exec ${run}";
+
+        serviceConfig = {
+          Type = "oneshot";
+          IOSchedulingClass = "idle";
+          NoNewPrivileges = "true";
+          CapabilityBoundingSet = [ "CAP_DAC_READ_SEARCH" ];
+          PermissionsStartOnly = "true";
+        };
+      }) gcfg.archives) //
+
+      (mapAttrs' (name: cfg: nameValuePair "tarsnap-restore-${name}"{
+        description = "Tarsnap restore '${name}'";
+        requires    = [ "network-online.target" ];
+
+        path = with pkgs; [ iputils tarsnap util-linux ];
+
+        script = let
+          tarsnap = ''tarsnap --configfile "/etc/tarsnap/${name}.conf"'';
+          lastArchive = "$(${tarsnap} --list-archives | sort | tail -1)";
+          run = ''${tarsnap} -x -f "${lastArchive}" ${optionalString cfg.verbose "-v"}'';
+          cachedir = escapeShellArg cfg.cachedir;
+
+        in if (cfg.cachedir != null) then ''
+          mkdir -p ${cachedir}
+          chmod 0700 ${cachedir}
+
+          ( flock 9
+            if [ ! -e ${cachedir}/firstrun ]; then
+              ( flock 10
+                flock -u 9
+                ${tarsnap} --fsck
+                flock 9
+              ) 10>${cachedir}/firstrun
+            fi
+          ) 9>${cachedir}/lockf
+
+           exec flock ${cachedir}/firstrun ${run}
+        '' else "exec ${run}";
+
+        serviceConfig = {
+          Type = "oneshot";
+          IOSchedulingClass = "idle";
+          NoNewPrivileges = "true";
+          CapabilityBoundingSet = [ "CAP_DAC_READ_SEARCH" ];
+          PermissionsStartOnly = "true";
+        };
+      }) gcfg.archives);
+
+    # Note: the timer must be Persistent=true, so that systemd will start it even
+    # if e.g. your laptop was asleep while the latest interval occurred.
+    systemd.timers = mapAttrs' (name: cfg: nameValuePair "tarsnap-${name}"
+      { timerConfig.OnCalendar = cfg.period;
+        timerConfig.Persistent = "true";
+        wantedBy = [ "timers.target" ];
+      }) gcfg.archives;
+
+    environment.etc =
+      mapAttrs' (name: cfg: nameValuePair "tarsnap/${name}.conf"
+        { text = configFile name cfg;
+        }) gcfg.archives;
+
+    environment.systemPackages = [ pkgs.tarsnap ];
+  };
+}
diff --git a/nixos/modules/services/backup/tsm.nix b/nixos/modules/services/backup/tsm.nix
new file mode 100644
index 00000000000..4e690ac6ecd
--- /dev/null
+++ b/nixos/modules/services/backup/tsm.nix
@@ -0,0 +1,125 @@
+{ config, lib, ... }:
+
+let
+
+  inherit (lib.attrsets) hasAttr;
+  inherit (lib.modules) mkDefault mkIf;
+  inherit (lib.options) mkEnableOption mkOption;
+  inherit (lib.types) nonEmptyStr nullOr;
+
+  options.services.tsmBackup = {
+    enable = mkEnableOption ''
+      automatic backups with the
+      IBM Spectrum Protect (Tivoli Storage Manager, TSM) client.
+      This also enables
+      <option>programs.tsmClient.enable</option>
+    '';
+    command = mkOption {
+      type = nonEmptyStr;
+      default = "backup";
+      example = "incr";
+      description = ''
+        The actual command passed to the
+        <literal>dsmc</literal> executable to start the backup.
+      '';
+    };
+    servername = mkOption {
+      type = nonEmptyStr;
+      example = "mainTsmServer";
+      description = ''
+        Create a systemd system service
+        <literal>tsm-backup.service</literal> that starts
+        a backup based on the given servername's stanza.
+        Note that this server's
+        <option>passwdDir</option> will default to
+        <filename>/var/lib/tsm-backup/password</filename>
+        (but may be overridden);
+        also, the service will use
+        <filename>/var/lib/tsm-backup</filename> as
+        <literal>HOME</literal> when calling
+        <literal>dsmc</literal>.
+      '';
+    };
+    autoTime = mkOption {
+      type = nullOr nonEmptyStr;
+      default = null;
+      example = "12:00";
+      description = ''
+        The backup service will be invoked
+        automatically at the given date/time,
+        which must be in the format described in
+        <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+        The default <literal>null</literal>
+        disables automatic backups.
+      '';
+    };
+  };
+
+  cfg = config.services.tsmBackup;
+  cfgPrg = config.programs.tsmClient;
+
+  assertions = [
+    {
+      assertion = hasAttr cfg.servername cfgPrg.servers;
+      message = "TSM service servername not found in list of servers";
+    }
+    {
+      assertion = cfgPrg.servers.${cfg.servername}.genPasswd;
+      message = "TSM service requires automatic password generation";
+    }
+  ];
+
+in
+
+{
+
+  inherit options;
+
+  config = mkIf cfg.enable {
+    inherit assertions;
+    programs.tsmClient.enable = true;
+    programs.tsmClient.servers.${cfg.servername}.passwdDir =
+      mkDefault "/var/lib/tsm-backup/password";
+    systemd.services.tsm-backup = {
+      description = "IBM Spectrum Protect (Tivoli Storage Manager) Backup";
+      # DSM_LOG needs a trailing slash to have it treated as a directory.
+      # `/var/log` would be littered with TSM log files otherwise.
+      environment.DSM_LOG = "/var/log/tsm-backup/";
+      # TSM needs a HOME dir to store certificates.
+      environment.HOME = "/var/lib/tsm-backup";
+      serviceConfig = {
+        # for exit status description see
+        # https://www.ibm.com/docs/en/spectrum-protect/8.1.13?topic=clients-client-return-codes
+        SuccessExitStatus = "4 8";
+        # The `-se` option must come after the command.
+        # The `-optfile` option suppresses a `dsm.opt`-not-found warning.
+        ExecStart =
+          "${cfgPrg.wrappedPackage}/bin/dsmc ${cfg.command} -se='${cfg.servername}' -optfile=/dev/null";
+        LogsDirectory = "tsm-backup";
+        StateDirectory = "tsm-backup";
+        StateDirectoryMode = "0750";
+        # systemd sandboxing
+        LockPersonality = true;
+        NoNewPrivileges = true;
+        PrivateDevices = true;
+        #PrivateTmp = true;  # would break backup of {/var,}/tmp
+        #PrivateUsers = true;  # would block backup of /home/*
+        ProtectClock = true;
+        ProtectControlGroups = true;
+        ProtectHome = "read-only";
+        ProtectHostname = true;
+        ProtectKernelLogs = true;
+        ProtectKernelModules = true;
+        ProtectKernelTunables = true;
+        ProtectProc = "noaccess";
+        ProtectSystem = "strict";
+        RestrictNamespaces = true;
+        RestrictSUIDSGID = true;
+      };
+      startAt = mkIf (cfg.autoTime!=null) cfg.autoTime;
+    };
+  };
+
+  meta.maintainers = [ lib.maintainers.yarny ];
+
+}
diff --git a/nixos/modules/services/backup/zfs-replication.nix b/nixos/modules/services/backup/zfs-replication.nix
new file mode 100644
index 00000000000..6d75774c78f
--- /dev/null
+++ b/nixos/modules/services/backup/zfs-replication.nix
@@ -0,0 +1,90 @@
+{ lib, pkgs, config, ... }:
+
+with lib;
+
+let
+  cfg = config.services.zfs.autoReplication;
+  recursive = optionalString cfg.recursive " --recursive";
+  followDelete = optionalString cfg.followDelete " --follow-delete";
+in {
+  options = {
+    services.zfs.autoReplication = {
+      enable = mkEnableOption "ZFS snapshot replication.";
+
+      followDelete = mkOption {
+        description = "Remove remote snapshots that don't have a local correspondant.";
+        default = true;
+        type = types.bool;
+      };
+
+      host = mkOption {
+        description = "Remote host where snapshots should be sent. <literal>lz4</literal> is expected to be installed on this host.";
+        example = "example.com";
+        type = types.str;
+      };
+
+      identityFilePath = mkOption {
+        description = "Path to SSH key used to login to host.";
+        example = "/home/username/.ssh/id_rsa";
+        type = types.path;
+      };
+
+      localFilesystem = mkOption {
+        description = "Local ZFS fileystem from which snapshots should be sent.  Defaults to the attribute name.";
+        example = "pool/file/path";
+        type = types.str;
+      };
+
+      remoteFilesystem = mkOption {
+        description = "Remote ZFS filesystem where snapshots should be sent.";
+        example = "pool/file/path";
+        type = types.str;
+      };
+
+      recursive = mkOption {
+        description = "Recursively discover snapshots to send.";
+        default = true;
+        type = types.bool;
+      };
+
+      username = mkOption {
+        description = "Username used by SSH to login to remote host.";
+        example = "username";
+        type = types.str;
+      };
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    environment.systemPackages = [
+      pkgs.lz4
+    ];
+
+    systemd.services.zfs-replication = {
+      after = [
+        "zfs-snapshot-daily.service"
+        "zfs-snapshot-frequent.service"
+        "zfs-snapshot-hourly.service"
+        "zfs-snapshot-monthly.service"
+        "zfs-snapshot-weekly.service"
+      ];
+      description = "ZFS Snapshot Replication";
+      documentation = [
+        "https://github.com/alunduil/zfs-replicate"
+      ];
+      restartIfChanged = false;
+      serviceConfig.ExecStart = "${pkgs.zfs-replicate}/bin/zfs-replicate${recursive} -l ${escapeShellArg cfg.username} -i ${escapeShellArg cfg.identityFilePath}${followDelete} ${escapeShellArg cfg.host} ${escapeShellArg cfg.remoteFilesystem} ${escapeShellArg cfg.localFilesystem}";
+      wantedBy = [
+        "zfs-snapshot-daily.service"
+        "zfs-snapshot-frequent.service"
+        "zfs-snapshot-hourly.service"
+        "zfs-snapshot-monthly.service"
+        "zfs-snapshot-weekly.service"
+      ];
+    };
+  };
+
+  meta = {
+    maintainers = with lib.maintainers; [ alunduil ];
+  };
+}
diff --git a/nixos/modules/services/backup/znapzend.nix b/nixos/modules/services/backup/znapzend.nix
new file mode 100644
index 00000000000..09e60177c39
--- /dev/null
+++ b/nixos/modules/services/backup/znapzend.nix
@@ -0,0 +1,469 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+with types;
+
+let
+
+  planDescription = ''
+      The znapzend backup plan to use for the source.
+
+      The plan specifies how often to backup and for how long to keep the
+      backups. It consists of a series of retention periodes to interval
+      associations:
+
+      <literal>
+        retA=>intA,retB=>intB,...
+      </literal>
+
+      Both intervals and retention periods are expressed in standard units
+      of time or multiples of them. You can use both the full name or a
+      shortcut according to the following listing:
+
+      <literal>
+        second|sec|s, minute|min, hour|h, day|d, week|w, month|mon|m, year|y
+      </literal>
+
+      See <citerefentry><refentrytitle>znapzendzetup</refentrytitle><manvolnum>1</manvolnum></citerefentry> for more info.
+  '';
+  planExample = "1h=>10min,1d=>1h,1w=>1d,1m=>1w,1y=>1m";
+
+  # A type for a string of the form number{b|k|M|G}
+  mbufferSizeType = str // {
+    check = x: str.check x && builtins.isList (builtins.match "^[0-9]+[bkMG]$" x);
+    description = "string of the form number{b|k|M|G}";
+  };
+
+  enabledFeatures = concatLists (mapAttrsToList (name: enabled: optional enabled name) cfg.features);
+
+  # Type for a string that must contain certain other strings (the list parameter).
+  # Note that these would need regex escaping.
+  stringContainingStrings = list: let
+    matching = s: map (str: builtins.match ".*${str}.*" s) list;
+  in str // {
+    check = x: str.check x && all isList (matching x);
+    description = "string containing all of the characters ${concatStringsSep ", " list}";
+  };
+
+  timestampType = stringContainingStrings [ "%Y" "%m" "%d" "%H" "%M" "%S" ];
+
+  destType = srcConfig: submodule ({ name, ... }: {
+    options = {
+
+      label = mkOption {
+        type = str;
+        description = "Label for this destination. Defaults to the attribute name.";
+      };
+
+      plan = mkOption {
+        type = str;
+        description = planDescription;
+        example = planExample;
+      };
+
+      dataset = mkOption {
+        type = str;
+        description = "Dataset name to send snapshots to.";
+        example = "tank/main";
+      };
+
+      host = mkOption {
+        type = nullOr str;
+        description = ''
+          Host to use for the destination dataset. Can be prefixed with
+          <literal>user@</literal> to specify the ssh user.
+        '';
+        default = null;
+        example = "john@example.com";
+      };
+
+      presend = mkOption {
+        type = nullOr str;
+        description = ''
+          Command to run before sending the snapshot to the destination.
+          Intended to run a remote script via <command>ssh</command> on the
+          destination, e.g. to bring up a backup disk or server or to put a
+          zpool online/offline. See also <option>postsend</option>.
+        '';
+        default = null;
+        example = "ssh root@bserv zpool import -Nf tank";
+      };
+
+      postsend = mkOption {
+        type = nullOr str;
+        description = ''
+          Command to run after sending the snapshot to the destination.
+          Intended to run a remote script via <command>ssh</command> on the
+          destination, e.g. to bring up a backup disk or server or to put a
+          zpool online/offline. See also <option>presend</option>.
+        '';
+        default = null;
+        example = "ssh root@bserv zpool export tank";
+      };
+    };
+
+    config = {
+      label = mkDefault name;
+      plan = mkDefault srcConfig.plan;
+    };
+  });
+
+
+
+  srcType = submodule ({ name, config, ... }: {
+    options = {
+
+      enable = mkOption {
+        type = bool;
+        description = "Whether to enable this source.";
+        default = true;
+      };
+
+      recursive = mkOption {
+        type = bool;
+        description = "Whether to do recursive snapshots.";
+        default = false;
+      };
+
+      mbuffer = {
+        enable = mkOption {
+          type = bool;
+          description = "Whether to use <command>mbuffer</command>.";
+          default = false;
+        };
+
+        port = mkOption {
+          type = nullOr ints.u16;
+          description = ''
+              Port to use for <command>mbuffer</command>.
+
+              If this is null, it will run <command>mbuffer</command> through
+              ssh.
+
+              If this is not null, it will run <command>mbuffer</command>
+              directly through TCP, which is not encrypted but faster. In that
+              case the given port needs to be open on the destination host.
+          '';
+          default = null;
+        };
+
+        size = mkOption {
+          type = mbufferSizeType;
+          description = ''
+            The size for <command>mbuffer</command>.
+            Supports the units b, k, M, G.
+          '';
+          default = "1G";
+          example = "128M";
+        };
+      };
+
+      presnap = mkOption {
+        type = nullOr str;
+        description = ''
+          Command to run before snapshots are taken on the source dataset,
+          e.g. for database locking/flushing. See also
+          <option>postsnap</option>.
+        '';
+        default = null;
+        example = literalExpression ''
+          '''''${pkgs.mariadb}/bin/mysql -e "set autocommit=0;flush tables with read lock;\\! ''${pkgs.coreutils}/bin/sleep 600" &  ''${pkgs.coreutils}/bin/echo $! > /tmp/mariadblock.pid ; sleep 10'''
+        '';
+      };
+
+      postsnap = mkOption {
+        type = nullOr str;
+        description = ''
+          Command to run after snapshots are taken on the source dataset,
+          e.g. for database unlocking. See also <option>presnap</option>.
+        '';
+        default = null;
+        example = literalExpression ''
+          "''${pkgs.coreutils}/bin/kill `''${pkgs.coreutils}/bin/cat /tmp/mariadblock.pid`;''${pkgs.coreutils}/bin/rm /tmp/mariadblock.pid"
+        '';
+      };
+
+      timestampFormat = mkOption {
+        type = timestampType;
+        description = ''
+          The timestamp format to use for constructing snapshot names.
+          The syntax is <literal>strftime</literal>-like. The string must
+          consist of the mandatory <literal>%Y %m %d %H %M %S</literal>.
+          Optionally  <literal>- _ . :</literal>  characters as well as any
+          alphanumeric character are allowed. If suffixed by a
+          <literal>Z</literal>, times will be in UTC.
+        '';
+        default = "%Y-%m-%d-%H%M%S";
+        example = "znapzend-%m.%d.%Y-%H%M%SZ";
+      };
+
+      sendDelay = mkOption {
+        type = int;
+        description = ''
+          Specify delay (in seconds) before sending snaps to the destination.
+          May be useful if you want to control sending time.
+        '';
+        default = 0;
+        example = 60;
+      };
+
+      plan = mkOption {
+        type = str;
+        description = planDescription;
+        example = planExample;
+      };
+
+      dataset = mkOption {
+        type = str;
+        description = "The dataset to use for this source.";
+        example = "tank/home";
+      };
+
+      destinations = mkOption {
+        type = attrsOf (destType config);
+        description = "Additional destinations.";
+        default = {};
+        example = literalExpression ''
+          {
+            local = {
+              dataset = "btank/backup";
+              presend = "zpool import -N btank";
+              postsend = "zpool export btank";
+            };
+            remote = {
+              host = "john@example.com";
+              dataset = "tank/john";
+            };
+          };
+        '';
+      };
+    };
+
+    config = {
+      dataset = mkDefault name;
+    };
+
+  });
+
+  ### Generating the configuration from here
+
+  cfg = config.services.znapzend;
+
+  onOff = b: if b then "on" else "off";
+  nullOff = b: if b == null then "off" else toString b;
+  stripSlashes = replaceStrings [ "/" ] [ "." ];
+
+  attrsToFile = config: concatStringsSep "\n" (builtins.attrValues (
+    mapAttrs (n: v: "${n}=${v}") config));
+
+  mkDestAttrs = dst: with dst;
+    mapAttrs' (n: v: nameValuePair "dst_${label}${n}" v) ({
+      "" = optionalString (host != null) "${host}:" + dataset;
+      _plan = plan;
+    } // optionalAttrs (presend != null) {
+      _precmd = presend;
+    } // optionalAttrs (postsend != null) {
+      _pstcmd = postsend;
+    });
+
+  mkSrcAttrs = srcCfg: with srcCfg; {
+    enabled = onOff enable;
+    # mbuffer is not referenced by its full path to accomodate non-NixOS systems or differing mbuffer versions between source and target
+    mbuffer = with mbuffer; if enable then "mbuffer"
+        + optionalString (port != null) ":${toString port}" else "off";
+    mbuffer_size = mbuffer.size;
+    post_znap_cmd = nullOff postsnap;
+    pre_znap_cmd = nullOff presnap;
+    recursive = onOff recursive;
+    src = dataset;
+    src_plan = plan;
+    tsformat = timestampFormat;
+    zend_delay = toString sendDelay;
+  } // foldr (a: b: a // b) {} (
+    map mkDestAttrs (builtins.attrValues destinations)
+  );
+
+  files = mapAttrs' (n: srcCfg: let
+    fileText = attrsToFile (mkSrcAttrs srcCfg);
+  in {
+    name = srcCfg.dataset;
+    value = pkgs.writeText (stripSlashes srcCfg.dataset) fileText;
+  }) cfg.zetup;
+
+in
+{
+  options = {
+    services.znapzend = {
+      enable = mkEnableOption "ZnapZend ZFS backup daemon";
+
+      logLevel = mkOption {
+        default = "debug";
+        example = "warning";
+        type = enum ["debug" "info" "warning" "err" "alert"];
+        description = ''
+          The log level when logging to file. Any of debug, info, warning, err,
+          alert. Default in daemonized form is debug.
+        '';
+      };
+
+      logTo = mkOption {
+        type = str;
+        default = "syslog::daemon";
+        example = "/var/log/znapzend.log";
+        description = ''
+          Where to log to (syslog::&lt;facility&gt; or &lt;filepath&gt;).
+        '';
+      };
+
+      noDestroy = mkOption {
+        type = bool;
+        default = false;
+        description = "Does all changes to the filesystem except destroy.";
+      };
+
+      autoCreation = mkOption {
+        type = bool;
+        default = false;
+        description = "Automatically create the destination dataset if it does not exist.";
+      };
+
+      zetup = mkOption {
+        type = attrsOf srcType;
+        description = "Znapzend configuration.";
+        default = {};
+        example = literalExpression ''
+          {
+            "tank/home" = {
+              # Make snapshots of tank/home every hour, keep those for 1 day,
+              # keep every days snapshot for 1 month, etc.
+              plan = "1d=>1h,1m=>1d,1y=>1m";
+              recursive = true;
+              # Send all those snapshots to john@example.com:rtank/john as well
+              destinations.remote = {
+                host = "john@example.com";
+                dataset = "rtank/john";
+              };
+            };
+          };
+        '';
+      };
+
+      pure = mkOption {
+        type = bool;
+        description = ''
+          Do not persist any stateful znapzend setups. If this option is
+          enabled, your previously set znapzend setups will be cleared and only
+          the ones defined with this module will be applied.
+        '';
+        default = false;
+      };
+
+      features.oracleMode = mkEnableOption ''
+        Destroy snapshots one by one instead of using one long argument list.
+        If source and destination are out of sync for a long time, you may have
+        so many snapshots to destroy that the argument gets is too long and the
+        command fails.
+      '';
+      features.recvu = mkEnableOption ''
+        recvu feature which uses <literal>-u</literal> on the receiving end to keep the destination
+        filesystem unmounted.
+      '';
+      features.compressed = mkEnableOption ''
+        compressed feature which adds the options <literal>-Lce</literal> to
+        the <command>zfs send</command> command. When this is enabled, make
+        sure that both the sending and receiving pool have the same relevant
+        features enabled. Using <literal>-c</literal> will skip unneccessary
+        decompress-compress stages, <literal>-L</literal> is for large block
+        support and -e is for embedded data support. see
+        <citerefentry><refentrytitle>znapzend</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+        and <citerefentry><refentrytitle>zfs</refentrytitle><manvolnum>8</manvolnum></citerefentry>
+        for more info.
+      '';
+      features.sendRaw = mkEnableOption ''
+        sendRaw feature which adds the options <literal>-w</literal> to the
+        <command>zfs send</command> command. For encrypted source datasets this
+        instructs zfs not to decrypt before sending which results in a remote
+        backup that can't be read without the encryption key/passphrase, useful
+        when the remote isn't fully trusted or not physically secure. This
+        option must be used consistently, raw incrementals cannot be based on
+        non-raw snapshots and vice versa.
+      '';
+      features.skipIntermediates = mkEnableOption ''
+        Enable the skipIntermediates feature to send a single increment
+        between latest common snapshot and the newly made one. It may skip
+        several source snaps if the destination was offline for some time, and
+        it should skip snapshots not managed by znapzend. Normally for online
+        destinations, the new snapshot is sent as soon as it is created on the
+        source, so there are no automatic increments to skip.
+      '';
+      features.lowmemRecurse = mkEnableOption ''
+        use lowmemRecurse on systems where you have too many datasets, so a
+        recursive listing of attributes to find backup plans exhausts the
+        memory available to <command>znapzend</command>: instead, go the slower
+        way to first list all impacted dataset names, and then query their
+        configs one by one.
+      '';
+      features.zfsGetType = mkEnableOption ''
+        use zfsGetType if your <command>zfs get</command> supports a
+        <literal>-t</literal> argument for filtering by dataset type at all AND
+        lists properties for snapshots by default when recursing, so that there
+        is too much data to process while searching for backup plans.
+        If these two conditions apply to your system, the time needed for a
+        <literal>--recursive</literal> search for backup plans can literally
+        differ by hundreds of times (depending on the amount of snapshots in
+        that dataset tree... and a decent backup plan will ensure you have a lot
+        of those), so you would benefit from requesting this feature.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [ pkgs.znapzend ];
+
+    systemd.services = {
+      znapzend = {
+        description = "ZnapZend - ZFS Backup System";
+        wantedBy    = [ "zfs.target" ];
+        after       = [ "zfs.target" ];
+
+        path = with pkgs; [ zfs mbuffer openssh ];
+
+        preStart = optionalString cfg.pure ''
+          echo Resetting znapzend zetups
+          ${pkgs.znapzend}/bin/znapzendzetup list \
+            | grep -oP '(?<=\*\*\* backup plan: ).*(?= \*\*\*)' \
+            | xargs -I{} ${pkgs.znapzend}/bin/znapzendzetup delete "{}"
+        '' + concatStringsSep "\n" (mapAttrsToList (dataset: config: ''
+          echo Importing znapzend zetup ${config} for dataset ${dataset}
+          ${pkgs.znapzend}/bin/znapzendzetup import --write ${dataset} ${config} &
+        '') files) + ''
+          wait
+        '';
+
+        serviceConfig = {
+          # znapzendzetup --import apparently tries to connect to the backup
+          # host 3 times with a timeout of 30 seconds, leading to a startup
+          # delay of >90s when the host is down, which is just above the default
+          # service timeout of 90 seconds. Increase the timeout so it doesn't
+          # make the service fail in that case.
+          TimeoutStartSec = 180;
+          # Needs to have write access to ZFS
+          User = "root";
+          ExecStart = let
+            args = concatStringsSep " " [
+              "--logto=${cfg.logTo}"
+              "--loglevel=${cfg.logLevel}"
+              (optionalString cfg.noDestroy "--nodestroy")
+              (optionalString cfg.autoCreation "--autoCreation")
+              (optionalString (enabledFeatures != [])
+                "--features=${concatStringsSep "," enabledFeatures}")
+            ]; in "${pkgs.znapzend}/bin/znapzend ${args}";
+          ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
+          Restart = "on-failure";
+        };
+      };
+    };
+  };
+
+  meta.maintainers = with maintainers; [ infinisil SlothOfAnarchy ];
+}
diff --git a/nixos/modules/services/backup/zrepl.nix b/nixos/modules/services/backup/zrepl.nix
new file mode 100644
index 00000000000..4356479b663
--- /dev/null
+++ b/nixos/modules/services/backup/zrepl.nix
@@ -0,0 +1,54 @@
+{ config, pkgs, lib, ... }:
+
+with lib;
+let
+  cfg = config.services.zrepl;
+  format = pkgs.formats.yaml { };
+  configFile = format.generate "zrepl.yml" cfg.settings;
+in
+{
+  meta.maintainers = with maintainers; [ cole-h ];
+
+  options = {
+    services.zrepl = {
+      enable = mkEnableOption "zrepl";
+
+      settings = mkOption {
+        default = { };
+        description = ''
+          Configuration for zrepl. See <link
+          xlink:href="https://zrepl.github.io/configuration.html"/>
+          for more information.
+        '';
+        type = types.submodule {
+          freeformType = format.type;
+        };
+      };
+    };
+  };
+
+  ### Implementation ###
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [ pkgs.zrepl ];
+
+    # zrepl looks for its config in this location by default. This
+    # allows the use of e.g. `zrepl signal wakeup <job>` without having
+    # to specify the storepath of the config.
+    environment.etc."zrepl/zrepl.yml".source = configFile;
+
+    systemd.packages = [ pkgs.zrepl ];
+    systemd.services.zrepl = {
+      requires = [ "local-fs.target" ];
+      wantedBy = [ "zfs.target" ];
+      after = [ "zfs.target" ];
+
+      path = [ config.boot.zfs.package ];
+      restartTriggers = [ configFile ];
+
+      serviceConfig = {
+        Restart = "on-failure";
+      };
+    };
+  };
+}