nixos/digital-ocean-image: init

3 files changed, 361 insertions, 0 deletions

diff --git a/nixos/modules/virtualisation/digital-ocean-config.nix b/nixos/modules/virtualisation/digital-ocean-config.nix
new file mode 100644
index 00000000000..88cb0cd450e
--- /dev/null
+++ b/nixos/modules/virtualisation/digital-ocean-config.nix
@@ -0,0 +1,197 @@
+{ config, pkgs, lib, modulesPath, ... }:
+with lib;
+{
+  imports = [
+    (modulesPath + "/profiles/qemu-guest.nix")
+    (modulesPath + "/virtualisation/digital-ocean-init.nix")
+  ];
+  options.virtualisation.digitalOcean = with types; {
+    setRootPassword = mkOption {
+      type = bool;
+      default = false;
+      example = true;
+      description = "Whether to set the root password from the Digital Ocean metadata";
+    };
+    setSshKeys = mkOption {
+      type = bool;
+      default = true;
+      example = true;
+      description = "Whether to fetch ssh keys from Digital Ocean";
+    };
+    seedEntropy = mkOption {
+      type = bool;
+      default = true;
+      example = true;
+      description = "Whether to run the kernel RNG entropy seeding script from the Digital Ocean vendor data";
+    };
+  };
+  config =
+    let
+      cfg = config.virtualisation.digitalOcean;
+      hostName = config.networking.hostName;
+      doMetadataFile = "/run/do-metadata/v1.json";
+    in mkMerge [{
+      fileSystems."/" = {
+        device = "/dev/disk/by-label/nixos";
+        autoResize = true;
+        fsType = "ext4";
+      };
+      boot = {
+        growPartition = true;
+        kernelParams = [ "console=ttyS0" "panic=1" "boot.panic_on_fail" ];
+        initrd.kernelModules = [ "virtio_scsi" ];
+        kernelModules = [ "virtio_pci" "virtio_net" ];
+        loader = {
+          grub.device = "/dev/vda";
+          timeout = 0;
+          grub.configurationLimit = 0;
+        };
+      };
+      services.openssh = {
+        enable = mkDefault true;
+        passwordAuthentication = mkDefault false;
+      };
+      services.do-agent.enable = mkDefault true;
+      networking = {
+        hostName = mkDefault ""; # use Digital Ocean metadata server
+      };
+
+      /* Check for and wait for the metadata server to become reachable.
+       * This serves as a dependency for all the other metadata services. */
+      systemd.services.digitalocean-metadata = {
+        path = [ pkgs.curl ];
+        description = "Get host metadata provided by Digitalocean";
+        script = ''
+          set -eu
+          DO_DELAY_ATTEMPTS=0
+          while ! curl -fsSL -o $RUNTIME_DIRECTORY/v1.json http://169.254.169.254/metadata/v1.json; do
+            DO_DELAY_ATTEMPTS=$((DO_DELAY_ATTEMPTS + 1))
+            if (( $DO_DELAY_ATTEMPTS >= $DO_DELAY_ATTEMPTS_MAX )); then
+              echo "giving up"
+              exit 1
+            fi
+
+            echo "metadata unavailable, trying again in 1s..."
+            sleep 1
+          done
+          chmod 600 $RUNTIME_DIRECTORY/v1.json
+          '';
+        environment = {
+          DO_DELAY_ATTEMPTS_MAX = "10";
+        };
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+          RuntimeDirectory = "do-metadata";
+          RuntimeDirectoryPreserve = "yes";
+        };
+        unitConfig = {
+          ConditionPathExists = "!${doMetadataFile}";
+          After = [ "network-pre.target" ] ++
+            optional config.networking.dhcpcd.enable "dhcpcd.service" ++
+            optional config.systemd.network.enable "systemd-networkd.service";
+        };
+      };
+
+      /* Fetch the root password from the digital ocean metadata.
+       * There is no specific route for this, so we use jq to get
+       * it from the One Big JSON metadata blob */
+      systemd.services.digitalocean-set-root-password = mkIf cfg.setRootPassword {
+        path = [ pkgs.shadow pkgs.jq ];
+        description = "Set root password provided by Digitalocean";
+        wantedBy = [ "multi-user.target" ];
+        script = ''
+          set -eo pipefail
+          ROOT_PASSWORD=$(jq -er '.auth_key' ${doMetadataFile})
+          echo "root:$ROOT_PASSWORD" | chpasswd
+          mkdir -p /etc/do-metadata/set-root-password
+          '';
+        unitConfig = {
+          ConditionPathExists = "!/etc/do-metadata/set-root-password";
+          Before = optional config.services.openssh.enable "sshd.service";
+          After = [ "digitalocean-metadata.service" ];
+          Requires = [ "digitalocean-metadata.service" ];
+        };
+        serviceConfig = {
+          Type = "oneshot";
+        };
+      };
+
+      /* Set the hostname from Digital Ocean, unless the user configured it in
+       * the NixOS configuration. The cached metadata file isn't used here
+       * because the hostname is a mutable part of the droplet. */
+      systemd.services.digitalocean-set-hostname = mkIf (hostName == "") {
+        path = [ pkgs.curl pkgs.nettools ];
+        description = "Set hostname provided by Digitalocean";
+        wantedBy = [ "network.target" ];
+        script = ''
+          set -e
+          DIGITALOCEAN_HOSTNAME=$(curl -fsSL http://169.254.169.254/metadata/v1/hostname)
+          hostname "$DIGITALOCEAN_HOSTNAME"
+          if [[ ! -e /etc/hostname || -w /etc/hostname ]]; then
+            printf "%s\n" "$DIGITALOCEAN_HOSTNAME" > /etc/hostname
+          fi
+        '';
+        unitConfig = {
+          Before = [ "network.target" ];
+          After = [ "digitalocean-metadata.service" ];
+          Wants = [ "digitalocean-metadata.service" ];
+        };
+        serviceConfig = {
+          Type = "oneshot";
+        };
+      };
+
+      /* Fetch the ssh keys for root from Digital Ocean */
+      systemd.services.digitalocean-ssh-keys = mkIf cfg.setSshKeys {
+        description = "Set root ssh keys provided by Digital Ocean";
+        wantedBy = [ "multi-user.target" ];
+        path = [ pkgs.jq ];
+        script = ''
+          set -e
+          mkdir -m 0700 -p /root/.ssh
+          jq -er '.public_keys[]' ${doMetadataFile} > /root/.ssh/authorized_keys
+          chmod 600 /root/.ssh/authorized_keys
+        '';
+        serviceConfig = {
+          Type = "oneshot";
+          RemainAfterExit = true;
+        };
+        unitConfig = {
+          ConditionPathExists = "!/root/.ssh/authorized_keys";
+          Before = optional config.services.openssh.enable "sshd.service";
+          After = [ "digitalocean-metadata.service" ];
+          Requires = [ "digitalocean-metadata.service" ];
+        };
+      };
+
+      /* Initialize the RNG by running the entropy-seed script from the
+       * Digital Ocean metadata
+       */
+      systemd.services.digitalocean-entropy-seed = mkIf cfg.seedEntropy {
+        description = "Run the kernel RNG entropy seeding script from the Digital Ocean vendor data";
+        wantedBy = [ "network.target" ];
+        path = [ pkgs.jq pkgs.mpack ];
+        script = ''
+          set -eo pipefail
+          TEMPDIR=$(mktemp -d)
+          jq -er '.vendor_data' ${doMetadataFile} | munpack -tC $TEMPDIR
+          ENTROPY_SEED=$(grep -rl "DigitalOcean Entropy Seed script" $TEMPDIR)
+          ${pkgs.runtimeShell} $ENTROPY_SEED
+          rm -rf $TEMPDIR
+          '';
+        unitConfig = {
+          Before = [ "network.target" ];
+          After = [ "digitalocean-metadata.service" ];
+          Requires = [ "digitalocean-metadata.service" ];
+        };
+        serviceConfig = {
+          Type = "oneshot";
+        };
+      };
+
+    }
+  ];
+  meta.maintainers = with maintainers; [ arianvp eamsden ];
+}
+
diff --git a/nixos/modules/virtualisation/digital-ocean-image.nix b/nixos/modules/virtualisation/digital-ocean-image.nix
new file mode 100644
index 00000000000..b582e235d43
--- /dev/null
+++ b/nixos/modules/virtualisation/digital-ocean-image.nix
@@ -0,0 +1,69 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+let
+  cfg = config.virtualisation.digitalOceanImage;
+in
+{
+
+  imports = [ ./digital-ocean-config.nix ];
+
+  options = {
+    virtualisation.digitalOceanImage.diskSize = mkOption {
+      type = with types; int;
+      default = 4096;
+      description = ''
+        Size of disk image. Unit is MB.
+      '';
+    };
+
+    virtualisation.digitalOceanImage.configFile = mkOption {
+      type = with types; nullOr path;
+      default = null;
+      description = ''
+        A path to a configuration file which will be placed at
+        <literal>/etc/nixos/configuration.nix</literal> and be used when switching
+        to a new configuration. If set to <literal>null</literal>, a default
+        configuration is used that imports
+        <literal>(modulesPath + "/virtualisation/digital-ocean-config.nix")</literal>.
+      '';
+    };
+
+    virtualisation.digitalOceanImage.compressionMethod = mkOption {
+      type = types.enum [ "gzip" "bzip2" ];
+      default = "gzip";
+      example = "bzip2";
+      description = ''
+        Disk image compression method. Choose bzip2 to generate smaller images that
+        take longer to generate but will consume less metered storage space on your
+        Digital Ocean account.
+      '';
+    };
+  };
+
+  #### implementation
+  config = {
+
+    system.build.digitalOceanImage = import ../../lib/make-disk-image.nix {
+      name = "digital-ocean-image";
+      format = "qcow2";
+      postVM = let
+        compress = {
+          "gzip" = "${pkgs.gzip}/bin/gzip";
+          "bzip2" = "${pkgs.bzip2}/bin/bzip2";
+        }.${cfg.compressionMethod};
+      in ''
+        ${compress} $diskImage
+      '';
+      configFile = if cfg.configFile == null
+        then config.virtualisation.digitalOcean.defaultConfigFile
+        else cfg.configFile;
+      inherit (cfg) diskSize;
+      inherit config lib pkgs;
+    };
+
+  };
+
+  meta.maintainers = with maintainers; [ arianvp eamsden ];
+
+}
diff --git a/nixos/modules/virtualisation/digital-ocean-init.nix b/nixos/modules/virtualisation/digital-ocean-init.nix
new file mode 100644
index 00000000000..02f4de009fa
--- /dev/null
+++ b/nixos/modules/virtualisation/digital-ocean-init.nix
@@ -0,0 +1,95 @@
+{ config, pkgs, lib, ... }:
+with lib;
+let
+  cfg = config.virtualisation.digitalOcean;
+  defaultConfigFile = pkgs.writeText "digitalocean-configuration.nix" ''
+    { modulesPath, lib, ... }:
+    {
+      imports = lib.optional (builtins.pathExists ./do-userdata.nix) ./do-userdata.nix ++ [
+        (modulesPath + "/virtualisation/digital-ocean-config.nix")
+      ];
+    }
+  '';
+in {
+  options.virtualisation.digitalOcean.rebuildFromUserData = mkOption {
+    type = types.bool;
+    default = true;
+    example = true;
+    description = "Whether to reconfigure the system from Digital Ocean user data";
+  };
+  options.virtualisation.digitalOcean.defaultConfigFile = mkOption {
+    type = types.path;
+    default = defaultConfigFile;
+    defaultText = ''
+      The default configuration imports user-data if applicable and
+      <literal>(modulesPath + "/virtualisation/digital-ocean-config.nix")</literal>.
+    '';
+    description = ''
+      A path to a configuration file which will be placed at
+      <literal>/etc/nixos/configuration.nix</literal> and be used when switching to
+      a new configuration.
+    '';
+  };
+
+  config = {
+    systemd.services.digitalocean-init = mkIf cfg.rebuildFromUserData {
+      description = "Reconfigure the system from Digital Ocean userdata on startup";
+      wantedBy = [ "network-online.target" ];
+      unitConfig = {
+        ConditionPathExists = "!/etc/nixos/do-userdata.nix";
+        After = [ "digitalocean-metadata.service" "network-online.target" ];
+        Requires = [ "digitalocean-metadata.service" ];
+        X-StopOnRemoval = false;
+      };
+      serviceConfig = {
+        Type = "oneshot";
+        RemainAfterExit = true;
+      };
+      restartIfChanged = false;
+      path = [ pkgs.jq pkgs.gnused pkgs.gnugrep pkgs.systemd config.nix.package config.system.build.nixos-rebuild ];
+      environment = {
+        HOME = "/root";
+        NIX_PATH = concatStringsSep ":" [
+          "/nix/var/nix/profiles/per-user/root/channels/nixos"
+          "nixos-config=/etc/nixos/configuration.nix"
+          "/nix/var/nix/profiles/per-user/root/channels"
+        ];
+      };
+      script = ''
+        set -e
+        echo "attempting to fetch configuration from Digital Ocean user data..."
+        userData=$(mktemp)
+        if jq -er '.user_data' /run/do-metadata/v1.json > $userData; then
+          # If the user-data looks like it could be a nix expression,
+          # copy it over. Also, look for a magic three-hash comment and set
+          # that as the channel.
+          if nix-instantiate --parse $userData > /dev/null; then
+            channels="$(grep '^###' "$userData" | sed 's|###\s*||')"
+            printf "%s" "$channels" | while read channel; do
+              echo "writing channel: $channel"
+            done
+
+            if [[ -n "$channels" ]]; then
+              printf "%s" "$channels" > /root/.nix-channels
+              nix-channel --update
+            fi
+
+            echo "setting configuration from Digital Ocean user data"
+            cp "$userData" /etc/nixos/do-userdata.nix
+            if [[ ! -e /etc/nixos/configuration.nix ]]; then
+              install -m0644 ${cfg.defaultConfigFile} /etc/nixos/configuration.nix
+            fi
+          else
+            echo "user data does not appear to be a Nix expression; ignoring"
+            exit
+          fi
+
+          nixos-rebuild switch
+        else
+          echo "no user data is available"
+        fi
+        '';
+    };
+  };
+  meta.maintainers = with maintainers; [ arianvp eamsden ];
+}