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-rw-r--r--nixos/doc/manual/from_md/release-notes/rl-2205.section.xml23
-rw-r--r--nixos/doc/manual/man-nixos-rebuild.xml2
-rw-r--r--nixos/doc/manual/release-notes/rl-2205.section.md4
-rw-r--r--nixos/maintainers/scripts/azure-new/examples/basic/system.nix2
-rw-r--r--nixos/modules/installer/virtualbox-demo.nix2
-rw-r--r--nixos/modules/profiles/hardened.nix2
-rw-r--r--nixos/modules/security/misc.nix4
-rw-r--r--nixos/modules/services/continuous-integration/gitlab-runner.nix2
-rw-r--r--nixos/modules/services/continuous-integration/hercules-ci-agent/default.nix2
-rw-r--r--nixos/modules/services/continuous-integration/hydra/default.nix27
-rw-r--r--nixos/modules/services/misc/nix-daemon.nix660
-rw-r--r--nixos/modules/services/misc/nix-ssh-serve.nix2
-rw-r--r--nixos/modules/system/activation/top-level.nix2
-rw-r--r--nixos/modules/system/boot/binfmt.nix13
-rw-r--r--nixos/tests/containers-imperative.nix4
-rw-r--r--nixos/tests/hardened.nix2
-rw-r--r--nixos/tests/hibernate.nix10
-rw-r--r--nixos/tests/hydra/common.nix2
-rw-r--r--nixos/tests/installer.nix10
-rw-r--r--nixos/tests/iscsi-multipath-root.nix10
-rw-r--r--nixos/tests/iscsi-root.nix10
-rw-r--r--nixos/tests/nixops/default.nix2
-rw-r--r--nixos/tests/nixops/legacy/base-configuration.nix2
-rw-r--r--nixos/tests/os-prober.nix10
24 files changed, 471 insertions, 338 deletions
diff --git a/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml b/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml
index 9f5279732fe..8d8d70440e8 100644
--- a/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml
+++ b/nixos/doc/manual/from_md/release-notes/rl-2205.section.xml
@@ -533,6 +533,29 @@
       </listitem>
       <listitem>
         <para>
+          The configuration portion of the <literal>nix-daemon</literal>
+          module has been reworked and exposed as
+          <link xlink:href="options.html#opt-nix-settings">nix.settings</link>:
+        </para>
+        <itemizedlist spacing="compact">
+          <listitem>
+            <para>
+              Legacy options have been mapped to the corresponding
+              options under under
+              <link xlink:href="options.html#opt-nix.settings">nix.settings</link>
+              but may be deprecated in the future.
+            </para>
+          </listitem>
+          <listitem>
+            <para>
+              <link xlink:href="options.html#opt-nix.buildMachines.publicHostKey">nix.buildMachines.publicHostKey</link>
+              has been added.
+            </para>
+          </listitem>
+        </itemizedlist>
+      </listitem>
+      <listitem>
+        <para>
           The
           <literal>writers.writePyPy2</literal>/<literal>writers.writePyPy3</literal>
           and corresponding
diff --git a/nixos/doc/manual/man-nixos-rebuild.xml b/nixos/doc/manual/man-nixos-rebuild.xml
index 6c7fc57f8d8..ab2a5d83a08 100644
--- a/nixos/doc/manual/man-nixos-rebuild.xml
+++ b/nixos/doc/manual/man-nixos-rebuild.xml
@@ -453,7 +453,7 @@
       Allow ad-hoc remote builders for building the new system. This requires
       the user executing <command>nixos-rebuild</command> (usually root) to be
       configured as a trusted user in the Nix daemon. This can be achieved by
-      using the <literal>nix.trustedUsers</literal> NixOS option. Examples
+      using the <literal>nix.settings.trusted-users</literal> NixOS option. Examples
       values for that option are described in the <literal>Remote builds
       chapter</literal> in the Nix manual, (i.e. <command>--builders
       "ssh://bigbrother x86_64-linux"</command>). By specifying an empty string
diff --git a/nixos/doc/manual/release-notes/rl-2205.section.md b/nixos/doc/manual/release-notes/rl-2205.section.md
index 629672259b2..61305fe70d6 100644
--- a/nixos/doc/manual/release-notes/rl-2205.section.md
+++ b/nixos/doc/manual/release-notes/rl-2205.section.md
@@ -183,6 +183,10 @@ In addition to numerous new and upgraded packages, this release has the followin
 
   Similarly [virtualisation.vmVariantWithBootloader](#opt-virtualisation.vmVariantWithBootLoader) was added.
 
+- The configuration portion of the `nix-daemon` module has been reworked and exposed as [nix.settings](options.html#opt-nix-settings):
+  * Legacy options have been mapped to the corresponding options under under [nix.settings](options.html#opt-nix.settings) but may be deprecated in the future.
+  * [nix.buildMachines.publicHostKey](options.html#opt-nix.buildMachines.publicHostKey) has been added.
+
 - The `writers.writePyPy2`/`writers.writePyPy3` and corresponding `writers.writePyPy2Bin`/`writers.writePyPy3Bin` convenience functions to create executable Python 2/3 scripts using the PyPy interpreter were added.
 
 - The `influxdb2` package was split into `influxdb2-server` and
diff --git a/nixos/maintainers/scripts/azure-new/examples/basic/system.nix b/nixos/maintainers/scripts/azure-new/examples/basic/system.nix
index 855bd3bab71..d283742701d 100644
--- a/nixos/maintainers/scripts/azure-new/examples/basic/system.nix
+++ b/nixos/maintainers/scripts/azure-new/examples/basic/system.nix
@@ -17,7 +17,7 @@ in
     description = "Azure NixOS Test User";
     openssh.authorizedKeys.keys = [ (builtins.readFile ~/.ssh/id_ed25519.pub) ];
   };
-  nix.trustedUsers = [ username ];
+  nix.settings.trusted-users = [ username ];
 
   virtualisation.azureImage.diskSize = 2500;
 
diff --git a/nixos/modules/installer/virtualbox-demo.nix b/nixos/modules/installer/virtualbox-demo.nix
index 2768e17590b..27a7651382b 100644
--- a/nixos/modules/installer/virtualbox-demo.nix
+++ b/nixos/modules/installer/virtualbox-demo.nix
@@ -25,7 +25,7 @@ with lib;
 
   installer.cloneConfigExtra = ''
   # Let demo build as a trusted user.
-  # nix.trustedUsers = [ "demo" ];
+  # nix.settings.trusted-users = [ "demo" ];
 
   # Mount a VirtualBox shared folder.
   # This is configurable in the VirtualBox menu at
diff --git a/nixos/modules/profiles/hardened.nix b/nixos/modules/profiles/hardened.nix
index 3f8f78f012a..856ee480fc0 100644
--- a/nixos/modules/profiles/hardened.nix
+++ b/nixos/modules/profiles/hardened.nix
@@ -17,7 +17,7 @@ with lib;
 
   boot.kernelPackages = mkDefault pkgs.linuxPackages_hardened;
 
-  nix.allowedUsers = mkDefault [ "@users" ];
+  nix.settings.allowed-users = mkDefault [ "@users" ];
 
   environment.memoryAllocator.provider = mkDefault "scudo";
   environment.variables.SCUDO_OPTIONS = mkDefault "ZeroContents=1";
diff --git a/nixos/modules/security/misc.nix b/nixos/modules/security/misc.nix
index e7abc1e0d59..c20e067b8cc 100644
--- a/nixos/modules/security/misc.nix
+++ b/nixos/modules/security/misc.nix
@@ -123,8 +123,8 @@ with lib;
       boot.kernel.sysctl."user.max_user_namespaces" = 0;
 
       assertions = [
-        { assertion = config.nix.useSandbox -> config.security.allowUserNamespaces;
-          message = "`nix.useSandbox = true` conflicts with `!security.allowUserNamespaces`.";
+        { assertion = config.nix.settings.sandbox -> config.security.allowUserNamespaces;
+          message = "`nix.settings.sandbox = true` conflicts with `!security.allowUserNamespaces`.";
         }
       ];
     })
diff --git a/nixos/modules/services/continuous-integration/gitlab-runner.nix b/nixos/modules/services/continuous-integration/gitlab-runner.nix
index d4b8541c6a1..dc58c634523 100644
--- a/nixos/modules/services/continuous-integration/gitlab-runner.nix
+++ b/nixos/modules/services/continuous-integration/gitlab-runner.nix
@@ -147,7 +147,7 @@ in
     concurrent = mkOption {
       type = types.int;
       default = 1;
-      example = literalExpression "config.nix.maxJobs";
+      example = literalExpression "config.nix.settings.max-jobs";
       description = ''
         Limits how many jobs globally can be run concurrently.
         The most upper limit of jobs using all defined runners.
diff --git a/nixos/modules/services/continuous-integration/hercules-ci-agent/default.nix b/nixos/modules/services/continuous-integration/hercules-ci-agent/default.nix
index 968bc8f1e54..ef1933e1228 100644
--- a/nixos/modules/services/continuous-integration/hercules-ci-agent/default.nix
+++ b/nixos/modules/services/continuous-integration/hercules-ci-agent/default.nix
@@ -67,7 +67,7 @@ in
 
     # Trusted user allows simplified configuration and better performance
     # when operating in a cluster.
-    nix.trustedUsers = [ config.systemd.services.hercules-ci-agent.serviceConfig.User ];
+    nix.settings.trusted-users = [ config.systemd.services.hercules-ci-agent.serviceConfig.User ];
     services.hercules-ci-agent = {
       settings = {
         nixUserIsTrusted = true;
diff --git a/nixos/modules/services/continuous-integration/hydra/default.nix b/nixos/modules/services/continuous-integration/hydra/default.nix
index ccb7cc21734..cc5de97d6d1 100644
--- a/nixos/modules/services/continuous-integration/hydra/default.nix
+++ b/nixos/modules/services/continuous-integration/hydra/default.nix
@@ -258,8 +258,6 @@ in
         uid = config.ids.uids.hydra-www;
       };
 
-    nix.trustedUsers = [ "hydra-queue-runner" ];
-
     services.hydra.extraConfig =
       ''
         using_frontend_proxy = 1
@@ -277,16 +275,21 @@ in
 
     environment.variables = hydraEnv;
 
-    nix.extraOptions = ''
-      keep-outputs = true
-      keep-derivations = true
-
-
-    '' + optionalString (versionOlder (getVersion config.nix.package.out) "2.4pre") ''
-      # The default (`true') slows Nix down a lot since the build farm
-      # has so many GC roots.
-      gc-check-reachability = false
-    '';
+    nix.settings = mkMerge [
+      {
+        keep-outputs = true;
+        keep-derivations = true;
+        trusted-users = [ "hydra-queue-runner" ];
+      }
+
+      (mkIf (versionOlder (getVersion config.nix.package.out) "2.4pre")
+        {
+          # The default (`true') slows Nix down a lot since the build farm
+          # has so many GC roots.
+          gc-check-reachability = false;
+        }
+      )
+    ];
 
     systemd.services.hydra-init =
       { wantedBy = [ "multi-user.target" ];
diff --git a/nixos/modules/services/misc/nix-daemon.nix b/nixos/modules/services/misc/nix-daemon.nix
index 869feb05eb7..10f9a4afb36 100644
--- a/nixos/modules/services/misc/nix-daemon.nix
+++ b/nixos/modules/services/misc/nix-daemon.nix
@@ -6,20 +6,20 @@ let
 
   cfg = config.nix;
 
-  nix = cfg.package.out;
+  nixPackage = cfg.package.out;
 
-  nixVersion = getVersion nix;
-
-  isNix23 = versionAtLeast nixVersion "2.3pre";
+  isNixAtLeast = versionAtLeast (getVersion nixPackage);
 
   makeNixBuildUser = nr: {
-    name  = "nixbld${toString nr}";
+    name = "nixbld${toString nr}";
     value = {
       description = "Nix build user ${toString nr}";
 
-      /* For consistency with the setgid(2), setuid(2), and setgroups(2)
-         calls in `libstore/build.cc', don't add any supplementary group
-         here except "nixbld".  */
+      /*
+        For consistency with the setgid(2), setuid(2), and setgroups(2)
+        calls in `libstore/build.cc', don't add any supplementary group
+        here except "nixbld".
+      */
       uid = builtins.add config.ids.uids.nixbld nr;
       isSystemUser = true;
       group = "nixbld";
@@ -30,43 +30,82 @@ let
   nixbldUsers = listToAttrs (map makeNixBuildUser (range 1 cfg.nrBuildUsers));
 
   nixConf =
-    assert versionAtLeast nixVersion "2.2";
-    pkgs.runCommand "nix.conf" { preferLocalBuild = true; extraOptions = cfg.extraOptions; } (
-      ''
-        cat > $out <<END
+    assert isNixAtLeast "2.2";
+    let
+
+      mkValueString = v:
+        if v == null then ""
+        else if isInt v then toString v
+        else if isBool v then boolToString v
+        else if isFloat v then floatToString v
+        else if isList v then toString v
+        else if isDerivation v then toString v
+        else if builtins.isPath v then toString v
+        else if isString v then v
+        else if isCoercibleToString v then toString v
+        else abort "The nix conf value: ${toPretty {} v} can not be encoded";
+
+      mkKeyValue = k: v: "${escape [ "=" ] k} = ${mkValueString v}";
+
+      mkKeyValuePairs = attrs: concatStringsSep "\n" (mapAttrsToList mkKeyValue attrs);
+
+    in
+    pkgs.writeTextFile {
+      name = "nix.conf";
+      text = ''
         # WARNING: this file is generated from the nix.* options in
         # your NixOS configuration, typically
         # /etc/nixos/configuration.nix.  Do not edit it!
-        build-users-group = nixbld
-        max-jobs = ${toString (cfg.maxJobs)}
-        cores = ${toString (cfg.buildCores)}
-        sandbox = ${if (builtins.isBool cfg.useSandbox) then boolToString cfg.useSandbox else cfg.useSandbox}
-        extra-sandbox-paths = ${toString cfg.sandboxPaths}
-        substituters = ${toString cfg.binaryCaches}
-        trusted-substituters = ${toString cfg.trustedBinaryCaches}
-        trusted-public-keys = ${toString cfg.binaryCachePublicKeys}
-        auto-optimise-store = ${boolToString cfg.autoOptimiseStore}
-        require-sigs = ${boolToString cfg.requireSignedBinaryCaches}
-        trusted-users = ${toString cfg.trustedUsers}
-        allowed-users = ${toString cfg.allowedUsers}
-        ${optionalString (!cfg.distributedBuilds) ''
-          builders =
-        ''}
-        system-features = ${toString cfg.systemFeatures}
-        ${optionalString isNix23 ''
-          sandbox-fallback = false
-        ''}
-        $extraOptions
-        END
-      '' + optionalString cfg.checkConfig (
-            if pkgs.stdenv.hostPlatform != pkgs.stdenv.buildPlatform then ''
-              echo "Ignore nix.checkConfig when cross-compiling"
-            '' else ''
-              echo "Checking that Nix can read nix.conf..."
-              ln -s $out ./nix.conf
-              NIX_CONF_DIR=$PWD ${cfg.package}/bin/nix show-config ${optionalString isNix23 "--no-net --option experimental-features nix-command"} >/dev/null
-            '')
-      );
+        ${mkKeyValuePairs cfg.settings}
+        ${cfg.extraOptions}
+      '';
+      checkPhase =
+        if pkgs.stdenv.hostPlatform != pkgs.stdenv.buildPlatform then ''
+          echo "Ignoring validation for cross-compilation"
+        ''
+        else ''
+          echo "Validating generated nix.conf"
+          ln -s $out ./nix.conf
+          set -e
+          set +o pipefail
+          NIX_CONF_DIR=$PWD \
+            ${cfg.package}/bin/nix show-config ${optionalString (isNixAtLeast "2.3pre") "--no-net --option experimental-features nix-command"} \
+            |& sed -e 's/^warning:/error:/' \
+            | (! grep '${if cfg.checkConfig then "^error:" else "^error: unknown setting"}')
+          set -o pipefail
+        '';
+    };
+
+  legacyConfMappings = {
+    useSandbox = "sandbox";
+    buildCores = "cores";
+    maxJobs = "max-jobs";
+    sandboxPaths = "extra-sandbox-paths";
+    binaryCaches = "substituters";
+    trustedBinaryCaches = "trusted-substituters";
+    binaryCachePublicKeys = "trusted-public-keys";
+    autoOptimiseStore = "auto-optimise-store";
+    requireSignedBinaryCaches = "require-sigs";
+    trustedUsers = "trusted-users";
+    allowedUsers = "allowed-users";
+    systemFeatures = "system-feature";
+  };
+
+  semanticConfType = with types;
+    let
+      confAtom = nullOr
+        (oneOf [
+          bool
+          int
+          float
+          str
+          path
+          package
+        ]) // {
+        description = "Nix config atom (null, bool, int, float, str, path or package)";
+      };
+    in
+    attrsOf (either confAtom (listOf confAtom));
 
 in
 
@@ -76,7 +115,7 @@ in
     (mkRenamedOptionModule [ "nix" "chrootDirs" ] [ "nix" "sandboxPaths" ])
     (mkRenamedOptionModule [ "nix" "daemonIONiceLevel" ] [ "nix" "daemonIOSchedPriority" ])
     (mkRemovedOptionModule [ "nix" "daemonNiceLevel" ] "Consider nix.daemonCPUSchedPolicy instead.")
-  ];
+  ] ++ mapAttrsToList (oldConf: newConf: mkRenamedOptionModule [ "nix" oldConf ] [ "nix" "settings" newConf ]) legacyConfMappings;
 
   ###### interface
 
@@ -102,81 +141,6 @@ in
         '';
       };
 
-      maxJobs = mkOption {
-        type = types.either types.int (types.enum ["auto"]);
-        default = "auto";
-        example = 64;
-        description = ''
-          This option defines the maximum number of jobs that Nix will try to
-          build in parallel. The default is auto, which means it will use all
-          available logical cores. It is recommend to set it to the total
-          number of logical cores in your system (e.g., 16 for two CPUs with 4
-          cores each and hyper-threading).
-        '';
-      };
-
-      autoOptimiseStore = mkOption {
-        type = types.bool;
-        default = false;
-        example = true;
-        description = ''
-         If set to true, Nix automatically detects files in the store that have
-         identical contents, and replaces them with hard links to a single copy.
-         This saves disk space. If set to false (the default), you can still run
-         nix-store --optimise to get rid of duplicate files.
-        '';
-      };
-
-      buildCores = mkOption {
-        type = types.int;
-        default = 0;
-        example = 64;
-        description = ''
-          This option defines the maximum number of concurrent tasks during
-          one build. It affects, e.g., -j option for make.
-          The special value 0 means that the builder should use all
-          available CPU cores in the system. Some builds may become
-          non-deterministic with this option; use with care! Packages will
-          only be affected if enableParallelBuilding is set for them.
-        '';
-      };
-
-      useSandbox = mkOption {
-        type = types.either types.bool (types.enum ["relaxed"]);
-        default = true;
-        description = "
-          If set, Nix will perform builds in a sandboxed environment that it
-          will set up automatically for each build. This prevents impurities
-          in builds by disallowing access to dependencies outside of the Nix
-          store by using network and mount namespaces in a chroot environment.
-          This is enabled by default even though it has a possible performance
-          impact due to the initial setup time of a sandbox for each build. It
-          doesn't affect derivation hashes, so changing this option will not
-          trigger a rebuild of packages.
-        ";
-      };
-
-      sandboxPaths = mkOption {
-        type = types.listOf types.str;
-        default = [];
-        example = [ "/dev" "/proc" ];
-        description =
-          ''
-            Directories from the host filesystem to be included
-            in the sandbox.
-          '';
-      };
-
-      extraOptions = mkOption {
-        type = types.lines;
-        default = "";
-        example = ''
-          keep-outputs = true
-          keep-derivations = true
-        '';
-        description = "Additional text appended to <filename>nix.conf</filename>.";
-      };
-
       distributedBuilds = mkOption {
         type = types.bool;
         default = false;
@@ -187,7 +151,7 @@ in
       };
 
       daemonCPUSchedPolicy = mkOption {
-        type = types.enum ["other" "batch" "idle"];
+        type = types.enum [ "other" "batch" "idle" ];
         default = "other";
         example = "batch";
         description = ''
@@ -218,7 +182,7 @@ in
       };
 
       daemonIOSchedClass = mkOption {
-        type = types.enum ["best-effort" "idle"];
+        type = types.enum [ "best-effort" "idle" ];
         default = "best-effort";
         example = "idle";
         description = ''
@@ -250,11 +214,11 @@ in
           scheduling policy: With idle, priorities are not used in scheduling
           decisions. best-effort supports values in the range 0 (high) to 7
           (low).
-      '';
+        '';
       };
 
       buildMachines = mkOption {
-        type = types.listOf (types.submodule ({
+        type = types.listOf (types.submodule {
           options = {
             hostName = mkOption {
               type = types.str;
@@ -276,7 +240,7 @@ in
             };
             systems = mkOption {
               type = types.listOf types.str;
-              default = [];
+              default = [ ];
               example = [ "x86_64-linux" "aarch64-linux" ];
               description = ''
                 The system types the build machine can execute derivations on.
@@ -293,7 +257,7 @@ in
                 The username to log in as on the remote host. This user must be
                 able to log in and run nix commands non-interactively. It must
                 also be privileged to build derivations, so must be included in
-                <option>nix.trustedUsers</option>.
+                <option>nix.settings.trusted-users</option>.
               '';
             };
             sshKey = mkOption {
@@ -331,7 +295,7 @@ in
             };
             mandatoryFeatures = mkOption {
               type = types.listOf types.str;
-              default = [];
+              default = [ ];
               example = [ "big-parallel" ];
               description = ''
                 A list of features mandatory for this builder. The builder will
@@ -342,7 +306,7 @@ in
             };
             supportedFeatures = mkOption {
               type = types.listOf types.str;
-              default = [];
+              default = [ ];
               example = [ "kvm" "big-parallel" ];
               description = ''
                 A list of features supported by this builder. The builder will
@@ -350,9 +314,18 @@ in
                 list.
               '';
             };
+            publicHostKey = mkOption {
+              type = types.nullOr types.str;
+              default = null;
+              description = ''
+                The (base64-encoded) public host key of this builder. The field
+                is calculated via <command>base64 -w0 /etc/ssh/ssh_host_type_key.pub</command>.
+                If null, SSH will use its regular known-hosts file when connecting.
+              '';
+            };
           };
-        }));
-        default = [];
+        });
+        default = [ ];
         description = ''
           This option lists the machines to be used if distributed builds are
           enabled (see <option>nix.distributedBuilds</option>).
@@ -366,7 +339,7 @@ in
       envVars = mkOption {
         type = types.attrs;
         internal = true;
-        default = {};
+        default = { };
         description = "Environment variables used by Nix.";
       };
 
@@ -391,92 +364,13 @@ in
         '';
       };
 
-      binaryCaches = mkOption {
-        type = types.listOf types.str;
-        description = ''
-          List of binary cache URLs used to obtain pre-built binaries
-          of Nix packages.
-
-          By default https://cache.nixos.org/ is added,
-          to override it use <literal>lib.mkForce []</literal>.
-        '';
-      };
-
-      trustedBinaryCaches = mkOption {
-        type = types.listOf types.str;
-        default = [ ];
-        example = [ "https://hydra.nixos.org/" ];
-        description = ''
-          List of binary cache URLs that non-root users can use (in
-          addition to those specified using
-          <option>nix.binaryCaches</option>) by passing
-          <literal>--option binary-caches</literal> to Nix commands.
-        '';
-      };
-
-      requireSignedBinaryCaches = mkOption {
-        type = types.bool;
-        default = true;
-        description = ''
-          If enabled (the default), Nix will only download binaries from binary caches if
-          they are cryptographically signed with any of the keys listed in
-          <option>nix.binaryCachePublicKeys</option>. If disabled, signatures are neither
-          required nor checked, so it's strongly recommended that you use only
-          trustworthy caches and https to prevent man-in-the-middle attacks.
-        '';
-      };
-
-      binaryCachePublicKeys = mkOption {
-        type = types.listOf types.str;
-        example = [ "hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=" ];
-        description = ''
-          List of public keys used to sign binary caches. If
-          <option>nix.requireSignedBinaryCaches</option> is enabled,
-          then Nix will use a binary from a binary cache if and only
-          if it is signed by <emphasis>any</emphasis> of the keys
-          listed here. By default, only the key for
-          <uri>cache.nixos.org</uri> is included.
-        '';
-      };
-
-      trustedUsers = mkOption {
-        type = types.listOf types.str;
-        default = [ "root" ];
-        example = [ "root" "alice" "@wheel" ];
-        description = ''
-          A list of names of users that have additional rights when
-          connecting to the Nix daemon, such as the ability to specify
-          additional binary caches, or to import unsigned NARs. You
-          can also specify groups by prefixing them with
-          <literal>@</literal>; for instance,
-          <literal>@wheel</literal> means all users in the wheel
-          group.
-        '';
-      };
-
-      allowedUsers = mkOption {
-        type = types.listOf types.str;
-        default = [ "*" ];
-        example = [ "@wheel" "@builders" "alice" "bob" ];
-        description = ''
-          A list of names of users (separated by whitespace) that are
-          allowed to connect to the Nix daemon. As with
-          <option>nix.trustedUsers</option>, you can specify groups by
-          prefixing them with <literal>@</literal>. Also, you can
-          allow all users by specifying <literal>*</literal>. The
-          default is <literal>*</literal>. Note that trusted users are
-          always allowed to connect.
-        '';
-      };
-
       nixPath = mkOption {
         type = types.listOf types.str;
-        default =
-          [
-            "nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
-            "nixos-config=/etc/nixos/configuration.nix"
-            "/nix/var/nix/profiles/per-user/root/channels"
-          ];
+        default = [
+          "nixpkgs=/nix/var/nix/profiles/per-user/root/channels/nixos"
+          "nixos-config=/etc/nixos/configuration.nix"
+          "/nix/var/nix/profiles/per-user/root/channels"
+        ];
         description = ''
           The default Nix expression search path, used by the Nix
           evaluator to look up paths enclosed in angle brackets
@@ -484,45 +378,44 @@ in
         '';
       };
 
-      systemFeatures = mkOption {
-        type = types.listOf types.str;
-        example = [ "kvm" "big-parallel" "gccarch-skylake" ];
-        description = ''
-          The supported features of a machine
-        '';
-      };
-
       checkConfig = mkOption {
         type = types.bool;
         default = true;
         description = ''
-          If enabled (the default), checks that Nix can parse the generated nix.conf.
+          If enabled (the default), checks for data type mismatches and that Nix
+          can parse the generated nix.conf.
         '';
       };
 
       registry = mkOption {
         type = types.attrsOf (types.submodule (
           let
-            inputAttrs = types.attrsOf (types.oneOf [types.str types.int types.bool types.package]);
+            referenceAttrs = with types; attrsOf (oneOf [
+              str
+              int
+              bool
+              package
+            ]);
           in
           { config, name, ... }:
-          { options = {
+          {
+            options = {
               from = mkOption {
-                type = inputAttrs;
+                type = referenceAttrs;
                 example = { type = "indirect"; id = "nixpkgs"; };
                 description = "The flake reference to be rewritten.";
               };
               to = mkOption {
-                type = inputAttrs;
+                type = referenceAttrs;
                 example = { type = "github"; owner = "my-org"; repo = "my-nixpkgs"; };
-                description = "The flake reference to which <option>from></option> is to be rewritten.";
+                description = "The flake reference <option>from></option> is rewritten to.";
               };
               flake = mkOption {
                 type = types.nullOr types.attrs;
                 default = null;
                 example = literalExpression "nixpkgs";
                 description = ''
-                  The flake input to which <option>from></option> is to be rewritten.
+                  The flake input <option>from></option> is rewritten to.
                 '';
               };
               exact = mkOption {
@@ -537,35 +430,232 @@ in
             };
             config = {
               from = mkDefault { type = "indirect"; id = name; };
-              to = mkIf (config.flake != null)
-                ({ type = "path";
-                   path = config.flake.outPath;
-                 } // lib.filterAttrs
-                   (n: v: n == "lastModified" || n == "rev" || n == "revCount" || n == "narHash")
-                   config.flake);
+              to = mkIf (config.flake != null) (mkDefault
+                {
+                  type = "path";
+                  path = config.flake.outPath;
+                } // filterAttrs
+                (n: _: n == "lastModified" || n == "rev" || n == "revCount" || n == "narHash")
+                config.flake);
             };
           }
         ));
-        default = {};
+        default = { };
         description = ''
           A system-wide flake registry.
         '';
       };
 
-    };
+      extraOptions = mkOption {
+        type = types.lines;
+        default = "";
+        example = ''
+          keep-outputs = true
+          keep-derivations = true
+        '';
+        description = "Additional text appended to <filename>nix.conf</filename>.";
+      };
+
+      settings = mkOption {
+        type = types.submodule {
+          freeformType = semanticConfType;
+
+          options = {
+            max-jobs = mkOption {
+              type = types.either types.int (types.enum [ "auto" ]);
+              default = "auto";
+              example = 64;
+              description = ''
+                This option defines the maximum number of jobs that Nix will try to
+                build in parallel. The default is auto, which means it will use all
+                available logical cores. It is recommend to set it to the total
+                number of logical cores in your system (e.g., 16 for two CPUs with 4
+                cores each and hyper-threading).
+              '';
+            };
+
+            auto-optimise-store = mkOption {
+              type = types.bool;
+              default = false;
+              example = true;
+              description = ''
+                If set to true, Nix automatically detects files in the store that have
+                identical contents, and replaces them with hard links to a single copy.
+                This saves disk space. If set to false (the default), you can still run
+                nix-store --optimise to get rid of duplicate files.
+              '';
+            };
 
+            cores = mkOption {
+              type = types.int;
+              default = 0;
+              example = 64;
+              description = ''
+                This option defines the maximum number of concurrent tasks during
+                one build. It affects, e.g., -j option for make.
+                The special value 0 means that the builder should use all
+                available CPU cores in the system. Some builds may become
+                non-deterministic with this option; use with care! Packages will
+                only be affected if enableParallelBuilding is set for them.
+              '';
+            };
+
+            sandbox = mkOption {
+              type = types.either types.bool (types.enum [ "relaxed" ]);
+              default = true;
+              description = ''
+                If set, Nix will perform builds in a sandboxed environment that it
+                will set up automatically for each build. This prevents impurities
+                in builds by disallowing access to dependencies outside of the Nix
+                store by using network and mount namespaces in a chroot environment.
+                This is enabled by default even though it has a possible performance
+                impact due to the initial setup time of a sandbox for each build. It
+                doesn't affect derivation hashes, so changing this option will not
+                trigger a rebuild of packages.
+              '';
+            };
+
+            extra-sandbox-paths = mkOption {
+              type = types.listOf types.str;
+              default = [ ];
+              example = [ "/dev" "/proc" ];
+              description = ''
+                Directories from the host filesystem to be included
+                in the sandbox.
+              '';
+            };
+
+            substituters = mkOption {
+              type = types.listOf types.str;
+              description = ''
+                List of binary cache URLs used to obtain pre-built binaries
+                of Nix packages.
+
+                By default https://cache.nixos.org/ is added.
+              '';
+            };
+
+            trusted-substituters = mkOption {
+              type = types.listOf types.str;
+              default = [ ];
+              example = [ "https://hydra.nixos.org/" ];
+              description = ''
+                List of binary cache URLs that non-root users can use (in
+                addition to those specified using
+                <option>nix.settings.substituters</option>) by passing
+                <literal>--option binary-caches</literal> to Nix commands.
+              '';
+            };
+
+            require-sigs = mkOption {
+              type = types.bool;
+              default = true;
+              description = ''
+                If enabled (the default), Nix will only download binaries from binary caches if
+                they are cryptographically signed with any of the keys listed in
+                <option>nix.settings.trusted-public-keys</option>. If disabled, signatures are neither
+                required nor checked, so it's strongly recommended that you use only
+                trustworthy caches and https to prevent man-in-the-middle attacks.
+              '';
+            };
+
+            trusted-public-keys = mkOption {
+              type = types.listOf types.str;
+              example = [ "hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=" ];
+              description = ''
+                List of public keys used to sign binary caches. If
+                <option>nix.settings.trusted-public-keys</option> is enabled,
+                then Nix will use a binary from a binary cache if and only
+                if it is signed by <emphasis>any</emphasis> of the keys
+                listed here. By default, only the key for
+                <uri>cache.nixos.org</uri> is included.
+              '';
+            };
+
+            trusted-users = mkOption {
+              type = types.listOf types.str;
+              default = [ "root" ];
+              example = [ "root" "alice" "@wheel" ];
+              description = ''
+                A list of names of users that have additional rights when
+                connecting to the Nix daemon, such as the ability to specify
+                additional binary caches, or to import unsigned NARs. You
+                can also specify groups by prefixing them with
+                <literal>@</literal>; for instance,
+                <literal>@wheel</literal> means all users in the wheel
+                group.
+              '';
+            };
+
+            system-features = mkOption {
+              type = types.listOf types.str;
+              example = [ "kvm" "big-parallel" "gccarch-skylake" ];
+              description = ''
+                The set of features supported by the machine. Derivations
+                can express dependencies on system features through the
+                <literal>requiredSystemFeatures</literal> attribute.
+
+                By default, pseudo-features <literal>nixos-test</literal>, <literal>benchmark</literal>,
+                and <literal>big-parallel</literal> used in Nixpkgs are set, <literal>kvm</literal>
+                is also included in it is avaliable.
+              '';
+            };
+
+            allowed-users = mkOption {
+              type = types.listOf types.str;
+              default = [ "*" ];
+              example = [ "@wheel" "@builders" "alice" "bob" ];
+              description = ''
+                A list of names of users (separated by whitespace) that are
+                allowed to connect to the Nix daemon. As with
+                <option>nix.settings.trusted-users</option>, you can specify groups by
+                prefixing them with <literal>@</literal>. Also, you can
+                allow all users by specifying <literal>*</literal>. The
+                default is <literal>*</literal>. Note that trusted users are
+                always allowed to connect.
+              '';
+            };
+          };
+        };
+        default = { };
+        example = literalExpression ''
+          {
+            use-sandbox = true;
+            show-trace = true;
+
+            system-features = [ "big-parallel" "kvm" "recursive-nix" ];
+            sandbox-paths = { "/bin/sh" = "''${pkgs.busybox-sandbox-shell.out}/bin/busybox"; };
+          }
+        '';
+        description = ''
+          Configuration for Nix, see
+          <link xlink:href="https://nixos.org/manual/nix/stable/#sec-conf-file"/> or
+          <citerefentry>
+            <refentrytitle>nix.conf</refentrytitle>
+            <manvolnum>5</manvolnum>
+          </citerefentry> for avalaible options.
+          The value declared here will be translated directly to the key-value pairs Nix expects.
+          </para>
+          <para>
+          You can use <command>nix-instantiate --eval --strict '&lt;nixpkgs/nixos&gt;' -A config.nix.settings</command>
+          to view the current value. By default it is empty.
+          </para>
+          <para>
+          Nix configurations defined under <option>nix.*</option> will be translated and applied to this
+          option. In addition, configuration specified in <option>nix.extraOptions</option> which will be appended
+          verbatim to the resulting config file.
+        '';
+      };
+    };
   };
 
 
   ###### implementation
 
   config = mkIf cfg.enable {
-
-    nix.binaryCachePublicKeys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
-    nix.binaryCaches = [ "https://cache.nixos.org/" ];
-
     environment.systemPackages =
-      [ nix
+      [
+        nixPackage
         pkgs.nix-info
       ]
       ++ optional (config.programs.bash.enableCompletion) pkgs.nix-bash-completions;
@@ -579,44 +669,49 @@ in
 
     # List of machines for distributed Nix builds in the format
     # expected by build-remote.pl.
-    environment.etc."nix/machines" =
-      { enable = cfg.buildMachines != [];
-        text =
-          concatMapStrings (machine:
-            "${if machine.sshUser != null then "${machine.sshUser}@" else ""}${machine.hostName} "
-            + (if machine.system != null then machine.system else concatStringsSep "," machine.systems)
-            + " ${if machine.sshKey != null then machine.sshKey else "-"} ${toString machine.maxJobs} "
-            + toString (machine.speedFactor)
-            + " "
-            + concatStringsSep "," (machine.mandatoryFeatures ++ machine.supportedFeatures)
-            + " "
-            + concatStringsSep "," machine.mandatoryFeatures
+    environment.etc."nix/machines" = mkIf (cfg.buildMachines != [ ]) {
+      text =
+        concatMapStrings
+          (machine:
+            (concatStringsSep " " [
+              "${optionalString (machine.sshUser != null) "${machine.sshUser}@"}${machine.hostName}"
+              (if machine.system != null then machine.system else if machine.systems != [ ] then concatStringsSep "," machine.systems else "-")
+              (if machine.sshKey != null then machine.sshKey else "-")
+              (toString machine.maxJobs)
+              (toString machine.speedFactor)
+              (concatStringsSep "," machine.supportedFeatures)
+              (concatStringsSep "," machine.mandatoryFeatures)
+            ]
+            ++ optional (isNixAtLeast "2.4pre") (if machine.publicHostKey != null then machine.publicHostKey else "-"))
             + "\n"
-          ) cfg.buildMachines;
-      };
+          )
+          cfg.buildMachines;
+    };
+
     assertions =
-      let badMachine = m: m.system == null && m.systems == [];
-      in [
+      let badMachine = m: m.system == null && m.systems == [ ];
+      in
+      [
         {
-          assertion = !(builtins.any badMachine cfg.buildMachines);
+          assertion = !(any badMachine cfg.buildMachines);
           message = ''
             At least one system type (via <varname>system</varname> or
               <varname>systems</varname>) must be set for every build machine.
               Invalid machine specifications:
           '' + "      " +
-          (builtins.concatStringsSep "\n      "
-            (builtins.map (m: m.hostName)
-              (builtins.filter (badMachine) cfg.buildMachines)));
+          (concatStringsSep "\n      "
+            (map (m: m.hostName)
+              (filter (badMachine) cfg.buildMachines)));
         }
       ];
 
-
-    systemd.packages = [ nix ];
+    systemd.packages = [ nixPackage ];
 
     systemd.sockets.nix-daemon.wantedBy = [ "sockets.target" ];
 
     systemd.services.nix-daemon =
-      { path = [ nix pkgs.util-linux config.programs.ssh.package ]
+      {
+        path = [ nixPackage pkgs.util-linux config.programs.ssh.package ]
           ++ optionals cfg.distributedBuilds [ pkgs.gzip ];
 
         environment = cfg.envVars
@@ -626,7 +721,8 @@ in
         unitConfig.RequiresMountsFor = "/nix/store";
 
         serviceConfig =
-          { CPUSchedulingPolicy = cfg.daemonCPUSchedPolicy;
+          {
+            CPUSchedulingPolicy = cfg.daemonCPUSchedPolicy;
             IOSchedulingClass = cfg.daemonIOSchedClass;
             IOSchedulingPriority = cfg.daemonIOSchedPriority;
             LimitNOFILE = 4096;
@@ -636,9 +732,7 @@ in
       };
 
     # Set up the environment variables for running Nix.
-    environment.sessionVariables = cfg.envVars //
-      { NIX_PATH = cfg.nixPath;
-      };
+    environment.sessionVariables = cfg.envVars // { NIX_PATH = cfg.nixPath; };
 
     environment.extraInit =
       ''
@@ -647,7 +741,7 @@ in
         fi
       '';
 
-    nix.nrBuildUsers = mkDefault (lib.max 32 (if cfg.maxJobs == "auto" then 0 else cfg.maxJobs));
+    nix.nrBuildUsers = mkDefault (max 32 (if cfg.settings.max-jobs == "auto" then 0 else cfg.settings.max-jobs));
 
     users.users = nixbldUsers;
 
@@ -663,14 +757,26 @@ in
         fi
       '';
 
-    nix.systemFeatures = mkDefault (
-      [ "nixos-test" "benchmark" "big-parallel" "kvm" ] ++
-      optionals (pkgs.hostPlatform ? gcc.arch) (
-        # a builder can run code for `gcc.arch` and inferior architectures
-        [ "gccarch-${pkgs.hostPlatform.gcc.arch}" ] ++
-        map (x: "gccarch-${x}") lib.systems.architectures.inferiors.${pkgs.hostPlatform.gcc.arch}
-      )
-    );
+    # Legacy configuration conversion.
+    nix.settings = mkMerge [
+      {
+        trusted-public-keys = [ "cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=" ];
+        substituters = [ "https://cache.nixos.org/" ];
+
+        system-features = mkDefault (
+          [ "nixos-test" "benchmark" "big-parallel" "kvm" ] ++
+          optionals (pkgs.hostPlatform ? gcc.arch) (
+            # a builder can run code for `gcc.arch` and inferior architectures
+            [ "gccarch-${pkgs.hostPlatform.gcc.arch}" ] ++
+            map (x: "gccarch-${x}") systems.architectures.inferiors.${pkgs.hostPlatform.gcc.arch}
+          )
+        );
+      }
+
+      (mkIf (!cfg.distributedBuilds) { builders = null; })
+
+      (mkIf (isNixAtLeast "2.3pre") { sandbox-fallback = false; })
+    ];
 
   };
 
diff --git a/nixos/modules/services/misc/nix-ssh-serve.nix b/nixos/modules/services/misc/nix-ssh-serve.nix
index d5c64fdb264..355fad5db46 100644
--- a/nixos/modules/services/misc/nix-ssh-serve.nix
+++ b/nixos/modules/services/misc/nix-ssh-serve.nix
@@ -20,7 +20,7 @@ in {
       write = mkOption {
         type = types.bool;
         default = false;
-        description = "Whether to enable writing to the Nix store as a remote store via SSH. Note: the sshServe user is named nix-ssh and is not a trusted-user. nix-ssh should be added to the nix.trustedUsers option in most use cases, such as allowing remote building of derivations.";
+        description = "Whether to enable writing to the Nix store as a remote store via SSH. Note: the sshServe user is named nix-ssh and is not a trusted-user. nix-ssh should be added to the <option>nix.settings.trusted-users</option> option in most use cases, such as allowing remote building of derivations.";
       };
 
       keys = mkOption {
diff --git a/nixos/modules/system/activation/top-level.nix b/nixos/modules/system/activation/top-level.nix
index 18ac717f5dd..40afa551c7f 100644
--- a/nixos/modules/system/activation/top-level.nix
+++ b/nixos/modules/system/activation/top-level.nix
@@ -156,7 +156,7 @@ in
 
     specialisation = mkOption {
       default = {};
-      example = lib.literalExpression "{ fewJobsManyCores.configuration = { nix.buildCores = 0; nix.maxJobs = 1; }; }";
+      example = lib.literalExpression "{ fewJobsManyCores.configuration = { nix.settings = { core = 0; max-jobs = 1; }; }";
       description = ''
         Additional configurations to build. If
         <literal>inheritParentConfig</literal> is true, the system
diff --git a/nixos/modules/system/boot/binfmt.nix b/nixos/modules/system/boot/binfmt.nix
index 5bc603530f7..33748358e45 100644
--- a/nixos/modules/system/boot/binfmt.nix
+++ b/nixos/modules/system/boot/binfmt.nix
@@ -300,18 +300,15 @@ in {
         interpreterSandboxPath = dirOf (dirOf interpreterReg);
       } // (magics.${system} or (throw "Cannot create binfmt registration for system ${system}"));
     }) cfg.emulatedSystems);
-    # TODO: add a nix.extraPlatforms option to NixOS!
-    nix.extraOptions = lib.mkIf (cfg.emulatedSystems != []) ''
-      extra-platforms = ${toString (cfg.emulatedSystems ++ lib.optional pkgs.stdenv.hostPlatform.isx86_64 "i686-linux")}
-    '';
-    nix.sandboxPaths = lib.mkIf (cfg.emulatedSystems != []) (
-      let
+    nix.settings = lib.mkIf (cfg.emulatedSystems != []) {
+      extra-platforms = cfg.emulatedSystems ++ lib.optional pkgs.stdenv.hostPlatform.isx86_64 "i686-linux";
+      extra-sandbox-paths = let
         ruleFor = system: cfg.registrations.${system};
         hasWrappedRule = lib.any (system: (ruleFor system).wrapInterpreterInShell) cfg.emulatedSystems;
       in [ "/run/binfmt" ]
         ++ lib.optional hasWrappedRule "${pkgs.bash}"
-        ++ (map (system: (ruleFor system).interpreterSandboxPath) cfg.emulatedSystems)
-      );
+        ++ (map (system: (ruleFor system).interpreterSandboxPath) cfg.emulatedSystems);
+    };
 
     environment.etc."binfmt.d/nixos.conf".source = builtins.toFile "binfmt_nixos.conf"
       (lib.concatStringsSep "\n" (lib.mapAttrsToList makeBinfmtLine config.boot.binfmt.registrations));
diff --git a/nixos/tests/containers-imperative.nix b/nixos/tests/containers-imperative.nix
index a126a5480c0..14001657bee 100644
--- a/nixos/tests/containers-imperative.nix
+++ b/nixos/tests/containers-imperative.nix
@@ -10,8 +10,8 @@ import ./make-test-python.nix ({ pkgs, lib, ... }: {
 
       # XXX: Sandbox setup fails while trying to hardlink files from the host's
       #      store file system into the prepared chroot directory.
-      nix.useSandbox = false;
-      nix.binaryCaches = []; # don't try to access cache.nixos.org
+      nix.settings.sandbox = false;
+      nix.settings.substituters = []; # don't try to access cache.nixos.org
 
       virtualisation.writableStore = true;
       # Make sure we always have all the required dependencies for creating a
diff --git a/nixos/tests/hardened.nix b/nixos/tests/hardened.nix
index da7e0972e13..dc455f971f5 100644
--- a/nixos/tests/hardened.nix
+++ b/nixos/tests/hardened.nix
@@ -11,7 +11,7 @@ import ./make-test-python.nix ({ pkgs, ... } : {
       users.users.sybil = { isNormalUser = true; group = "wheel"; };
       imports = [ ../modules/profiles/hardened.nix ];
       environment.memoryAllocator.provider = "graphene-hardened";
-      nix.useSandbox = false;
+      nix.settings.sandbox = false;
       virtualisation.emptyDiskImages = [ 4096 ];
       boot.initrd.postDeviceCommands = ''
         ${pkgs.dosfstools}/bin/mkfs.vfat -n EFISYS /dev/vdb
diff --git a/nixos/tests/hibernate.nix b/nixos/tests/hibernate.nix
index 4f05b99a5a1..3880f1649bd 100644
--- a/nixos/tests/hibernate.nix
+++ b/nixos/tests/hibernate.nix
@@ -45,11 +45,11 @@ in makeTest {
         ../modules/profiles/base.nix
       ];
 
-      nix.binaryCaches = mkForce [ ];
-      nix.extraOptions = ''
-        hashed-mirrors =
-        connect-timeout = 1
-      '';
+      nix.settings = {
+        substituters = mkForce [];
+        hashed-mirrors = null;
+        connect-timeout = 1;
+      };
 
       virtualisation.diskSize = 8 * 1024;
       virtualisation.emptyDiskImages = [
diff --git a/nixos/tests/hydra/common.nix b/nixos/tests/hydra/common.nix
index 1a3a4d8fb3d..fdf2b2c6f6d 100644
--- a/nixos/tests/hydra/common.nix
+++ b/nixos/tests/hydra/common.nix
@@ -42,7 +42,7 @@
         hostName = "localhost";
         systems = [ system ];
       }];
-      binaryCaches = [];
+      settings.substituters = [];
     };
   };
 }
diff --git a/nixos/tests/installer.nix b/nixos/tests/installer.nix
index 7c7eb004e55..761020571fa 100644
--- a/nixos/tests/installer.nix
+++ b/nixos/tests/installer.nix
@@ -334,11 +334,11 @@ let
             (pkgs.grub2_efi.override { inherit zfsSupport; })
           ]);
 
-          nix.binaryCaches = mkForce [ ];
-          nix.extraOptions = ''
-            hashed-mirrors =
-            connect-timeout = 1
-          '';
+          nix.settings = {
+            substituters = mkForce [];
+            hashed-mirrors = null;
+            connect-timeout = 1;
+          };
         };
 
       };
diff --git a/nixos/tests/iscsi-multipath-root.nix b/nixos/tests/iscsi-multipath-root.nix
index a26fea503b6..92ae9990c94 100644
--- a/nixos/tests/iscsi-multipath-root.nix
+++ b/nixos/tests/iscsi-multipath-root.nix
@@ -111,11 +111,11 @@ import ./make-test-python.nix (
 
         environment.etc."initiator-root-disk-closure".source = nodes.initiatorRootDisk.config.system.build.toplevel;
 
-        nix.binaryCaches = lib.mkForce [ ];
-        nix.extraOptions = ''
-          hashed-mirrors =
-          connect-timeout = 1
-        '';
+        nix.settings = {
+          substituters = lib.mkForce [ ];
+          hashed-mirrors = null;
+          connect-timeout = 1;
+        };
       };
 
       initiatorRootDisk = { config, pkgs, modulesPath, lib, ... }: {
diff --git a/nixos/tests/iscsi-root.nix b/nixos/tests/iscsi-root.nix
index bda51d2c2e4..eb0719edc37 100644
--- a/nixos/tests/iscsi-root.nix
+++ b/nixos/tests/iscsi-root.nix
@@ -95,11 +95,11 @@ import ./make-test-python.nix (
 
             system.extraDependencies = [ nodes.initiatorRootDisk.config.system.build.toplevel ];
 
-            nix.binaryCaches = lib.mkForce [];
-            nix.extraOptions = ''
-              hashed-mirrors =
-              connect-timeout = 1
-            '';
+            nix.settings = {
+              substituters = lib.mkForce [];
+              hashed-mirrors = null;
+              connect-timeout = 1;
+            };
           };
 
           initiatorRootDisk = { config, pkgs, modulesPath, lib, ... }: {
diff --git a/nixos/tests/nixops/default.nix b/nixos/tests/nixops/default.nix
index ec3d028aaba..b25fc95f4b3 100644
--- a/nixos/tests/nixops/default.nix
+++ b/nixos/tests/nixops/default.nix
@@ -23,7 +23,7 @@ let
       deployer = { config, lib, nodes, pkgs, ... }: {
         imports = [ ../../modules/installer/cd-dvd/channel.nix ];
         environment.systemPackages = [ nixopsPkg ];
-        nix.binaryCaches = lib.mkForce [ ];
+        nix.settings.substituters = lib.mkForce [ ];
         users.users.person.isNormalUser = true;
         virtualisation.writableStore = true;
         virtualisation.additionalPaths = [
diff --git a/nixos/tests/nixops/legacy/base-configuration.nix b/nixos/tests/nixops/legacy/base-configuration.nix
index dba960f595c..7f1c07a5c4a 100644
--- a/nixos/tests/nixops/legacy/base-configuration.nix
+++ b/nixos/tests/nixops/legacy/base-configuration.nix
@@ -16,7 +16,7 @@ in
     (modulesPath + "/testing/test-instrumentation.nix")
   ];
   virtualisation.writableStore = true;
-  nix.binaryCaches = lib.mkForce [ ];
+  nix.settings.substituters = lib.mkForce [ ];
   virtualisation.graphics = false;
   documentation.enable = false;
   services.qemuGuest.enable = true;
diff --git a/nixos/tests/os-prober.nix b/nixos/tests/os-prober.nix
index c1e29b0f68b..90375450fe1 100644
--- a/nixos/tests/os-prober.nix
+++ b/nixos/tests/os-prober.nix
@@ -43,11 +43,11 @@ let
       # vda is a filesystem without partition table
       forceInstall = true;
     };
-    nix.binaryCaches = lib.mkForce [ ];
-    nix.extraOptions = ''
-      hashed-mirrors =
-      connect-timeout = 1
-    '';
+    nix.settings = {
+      substituters = lib.mkForce [];
+      hashed-mirrors = null;
+      connect-timeout = 1;
+    };
     # save some memory
     documentation.enable = false;
   };