chore(nix): factor out the Gerrit configuration to the Nix module

Signed-off-by: Raito Bezarius <raito@lix.systems>

nix/coordinator.nix

@@ -65,6 +65,34 @@ in
         example = "/run/agenix.d/signing-key";
       };
 
+      gerrit = {
+        domain = lib.mkOption {
+          type = lib.types.str;
+          description = "Domain to the Gerrit server";
+          example = "gerrit.lix.systems";
+        };
+
+        username = lib.mkOption {
+          type = lib.types.str;
+          description = "Username to log in to the Gerrit API";
+          example = "buildbot";
+        };
+
+        port = lib.mkOption {
+          type = lib.types.port;
+          description = "Port to log in to the Gerrit API";
+          example = 2022;
+        };
+
+        privateKeyFile = lib.mkOption {
+          type = lib.types.path;
+          description = ''
+            Path to the SSH private key to authenticate against the Gerrit API
+          '';
+          example = "/var/lib/buildbot/master/id_gerrit";
+        };
+      };
+
       binaryCache = {
         enable = lib.mkEnableOption " binary cache upload to a S3 bucket";
         profileCredentialsFile = lib.mkOption {
@@ -123,10 +151,10 @@ in
         ''
         ''
           GerritNixConfigurator(
-              "gerrit.lix.systems",
+              "${cfg.gerrit.domain}",
-              "buildbot",
+              "${cfg.gerrit.username}",
-              2022,
+              "${toString cfg.gerrit.port}",
-              "/var/lib/buildbot/master/id_gerrit",
+              "${cfg.gerrit.privateKeyFile}",
               url=${builtins.toJSON config.services.buildbot-master.buildbotUrl},
               nix_eval_max_memory_size=${builtins.toJSON cfg.evalMaxMemorySize},
               nix_eval_worker_count=${if cfg.evalWorkerCount == null then "None" else builtins.toString cfg.evalWorkerCount},