nixos/n8n: add custom nodes option (#484577)

nixos/modules/services/misc/n8n.nix

@@ -13,6 +13,13 @@ let
   regularEnv = lib.filterAttrs (name: _value: !(lib.hasSuffix "_FILE" name)) cfg.environment;
   fileBasedEnv = lib.filterAttrs (name: _value: lib.hasSuffix "_FILE" name) cfg.environment;
 
+  customNodesDir = pkgs.linkFarm "n8n-custom-nodes" (
+    map (pkg: {
+      name = pkg.pname;
+      path = "${pkg}/lib/node_modules/${pkg.pname}";
+    }) cfg.customNodes
+  );
+
   # Transform file-based env vars to point to credentials directory
   fileBasedEnvTransformed = lib.mapAttrs' (
     varName: _secretPath: lib.nameValuePair varName "%d/${envVarToCredName varName}"
@@ -34,6 +41,17 @@ in
 
     package = lib.mkPackageOption pkgs "n8n" { };
 
+    customNodes = lib.mkOption {
+      type = lib.types.listOf lib.types.package;
+      default = [ ];
+      example = lib.literalExpression "[ pkgs.n8n-nodes-carbonejs ]";
+      description = ''
+        List of custom n8n community node packages to load.
+        Each package is expected to be an npm package with an `n8n.nodes` entry in its `package.json`.
+        The packages are made available to n8n via the `N8N_CUSTOM_EXTENSIONS` environment variable.
+      '';
+    };
+
     openFirewall = lib.mkOption {
       type = lib.types.bool;
       default = false;
@@ -121,6 +139,9 @@ in
         // {
           HOME = config.services.n8n.environment.N8N_USER_FOLDER;
         }
+        // lib.optionalAttrs (cfg.customNodes != [ ]) {
+          N8N_CUSTOM_EXTENSIONS = toString customNodesDir;
+        }
         // fileBasedEnvTransformed;
       serviceConfig = {
         Type = "simple";

nixos/tests/n8n.nix

@@ -15,6 +15,7 @@ in
     {
       services.n8n = {
         enable = true;
+        customNodes = [ pkgs.n8n-nodes-carbonejs ];
         environment = {
           WEBHOOK_URL = webhookUrl;
           N8N_TEMPLATES_ENABLED = false;
@@ -41,5 +42,11 @@ in
     # Test _FILE environment variables
     machine.succeed("grep -qF 'LoadCredential=n8n_encryption_key_file:${secretFile}' /etc/systemd/system/n8n.service")
     machine.succeed("grep -qF 'N8N_ENCRYPTION_KEY_FILE=%d/n8n_encryption_key_file' /etc/systemd/system/n8n.service")
+
+    # Test custom nodes
+    machine.succeed("grep -qF 'N8N_CUSTOM_EXTENSIONS=' /etc/systemd/system/n8n.service")
+    custom_extensions_dir = machine.succeed("grep -oP 'N8N_CUSTOM_EXTENSIONS=\\K[^\"]+' /etc/systemd/system/n8n.service").strip()
+    machine.succeed(f"test -L {custom_extensions_dir}/n8n-nodes-carbonejs")
+    machine.succeed(f"test -f {custom_extensions_dir}/n8n-nodes-carbonejs/package.json")
   '';
 }

pkgs/by-name/n8/n8n-nodes-carbonejs/package.nix

@@ -0,0 +1,32 @@
+{
+  lib,
+  buildNpmPackage,
+  fetchFromGitHub,
+  nix-update-script,
+  n8n,
+}:
+
+buildNpmPackage (finalAttrs: {
+  pname = "n8n-nodes-carbonejs";
+  version = "1.2.0";
+
+  src = fetchFromGitHub {
+    owner = "jreyesr";
+    repo = "n8n-nodes-carbonejs";
+    tag = "v${finalAttrs.version}";
+    hash = "sha256-Dvl+Kc04i+hQ8rciT7n3oS4rtgke+HEqUszJnQa7UA0=";
+  };
+
+  npmDepsHash = "sha256-3VwejuSFGvJWNsitLKfVVpB8GnkTrrf/LLobNCpy8gU=";
+
+  passthru.updateScript = nix-update-script { };
+
+  meta = {
+    inherit (n8n.meta) platforms;
+    description = "n8n community node for rendering Word templates using Carbone.js";
+    homepage = "https://github.com/jreyesr/n8n-nodes-carbonejs";
+    changelog = "https://github.com/jreyesr/n8n-nodes-carbonejs/releases/tag/${finalAttrs.src.tag}";
+    license = lib.licenses.mit;
+    maintainers = with lib.maintainers; [ sweenu ];
+  };
+})