1 files changed, 108 insertions, 0 deletions

diff --git a/modules/build-client.nix b/modules/build-client.nix
new file mode 100644
index 00000000..763fdb38
--- /dev/null
+++ b/modules/build-client.nix
@@ -0,0 +1,108 @@
+{ flake, config, lib, hostName, ... }:
+
+with lib;
+
+let
+  cfg = config.nix.buildServers;
+
+  secretName = name: "nix-ssh-builder-${name}-private";
+in {
+  options = {
+    nix = {
+      buildServers = mkOption {
+        type = types.attrsOf (types.submodule {
+          options = {
+            address = mkOption {
+              type = types.str;
+            };
+
+            system = mkOption {
+              type = types.nullOr types.str;
+              default = null;
+              example = "x86_64-linux";
+              description = ''
+                The system type the build machine can execute derivations on.
+                Either this attribute or <varname>systems</varname> must be
+                present, where <varname>system</varname> takes precedence if
+                both are set.
+              '';
+            };
+            systems = mkOption {
+              type = types.listOf types.str;
+              default = [];
+              example = [ "x86_64-linux" "aarch64-linux" ];
+              description = ''
+                The system types the build machine can execute derivations on.
+                Either this attribute or <varname>system</varname> must be
+                present, where <varname>system</varname> takes precedence if
+                both are set.
+              '';
+            };
+            maxJobs = mkOption {
+              type = types.int;
+              default = 1;
+              description = ''
+                The number of concurrent jobs the build machine supports. The
+                build machine will enforce its own limits, but this allows hydra
+                to schedule better since there is no work-stealing between build
+                machines.
+              '';
+            };
+            speedFactor = mkOption {
+              type = types.int;
+              default = 1;
+              description = ''
+                The relative speed of this builder. This is an arbitrary integer
+                that indicates the speed of this builder, relative to other
+                builders. Higher is faster.
+              '';
+            };
+            mandatoryFeatures = mkOption {
+              type = types.listOf types.str;
+              default = [];
+              example = [ "big-parallel" ];
+              description = ''
+                A list of features mandatory for this builder. The builder will
+                be ignored for derivations that don't require all features in
+                this list. All mandatory features are automatically included in
+                <varname>supportedFeatures</varname>.
+              '';
+            };
+            supportedFeatures = mkOption {
+              type = types.listOf types.str;
+              default = [];
+              example = [ "kvm" "big-parallel" ];
+              description = ''
+                A list of features supported by this builder. The builder will
+                be ignored for derivations that require features not in this
+                list.
+              '';
+            };
+          };
+        });
+        default = {};
+      };
+    };
+  };
+  
+  config = mkIf (cfg != {}) {
+    programs.ssh.extraConfig = concatMapStringsSep "\n" ({ name, value }: ''
+      Host ${name}
+        User nix-ssh-builder
+        HostName ${value.address}
+        IdentitiesOnly yes
+        IdentityFile ${config.sops.secrets.${secretName name}.path}
+        ControlMaster auto
+        ControlPath /run/nix-ssh-builder-master-%r@%n:%p
+        ControlPersist 30m
+        Compression yes
+        ForwardAgent no
+        ServerAliveInterval 6
+        ServerAliveCountMax 10
+    '') (mapAttrsToList nameValuePair cfg);
+
+    sops.secrets = mapAttrs' (name: hCfg: nameValuePair (secretName name) { sopsFile = ../system-profiles/build-server/clients + "/${hostName}/private"; format = "binary"; }) cfg;
+
+    nix.buildMachines = mapAttrsToList (hostName: hCfg: { inherit hostName; inherit (hCfg) system systems maxJobs speedFactor mandatoryFeatures supportedFeatures; }) cfg;
+  };
+}