refactor: split n8n overlay override

docs/packages/README.md

@@ -36,7 +36,7 @@ These entries override upstream nixpkgs packages via `overlays.modifications`. T
 
 | Package | Source | Modification | Location |
 |---------|--------|--------------|----------|
-| `n8n` | `nixpkgs#n8n` | Pins a newer release and fetch hashes | `overlays/mods/default.nix` |
+| `n8n` | `nixpkgs#n8n` | Pins a newer release and fetch hashes | `overlays/mods/n8n.nix` |
 
 ### Pass-Through Packages
 

flake.nix

@@ -48,17 +48,7 @@
       import ./pkgs {inherit pkgs inputs;});
 
     # Overlays - can be imported in your system configuration
-    overlays = {
+    overlays = import ./overlays {inherit inputs;};
-      # Default overlay: adds all custom packages and applies package modifications.
-      default = final: prev:
-        import ./pkgs {
-          pkgs = final;
-          inputs = inputs;
-        }
-        // import ./overlays/mods {inherit prev;};
-
-      modifications = final: prev: import ./overlays/mods {inherit prev;};
-    };
 
     # NixOS modules - for system-level configuration
     nixosModules = {

overlays/default.nix

@@ -0,0 +1,16 @@
+{inputs, ...}: let
+  # Package modifications for upstream nixpkgs packages.
+  modifications = final: prev: {
+    n8n = import ./mods/n8n.nix {inherit prev;};
+  };
+in {
+  # Default overlay: adds all custom packages and applies package modifications.
+  default = final: prev:
+    import ../pkgs {
+      pkgs = final;
+      inherit inputs;
+    }
+    // (modifications final prev);
+
+  inherit modifications;
+}

overlays/mods/default.nix

@@ -1,57 +0,0 @@
-{prev}: {
-  # n8n advances quickly. Keep using nixpkgs' package expression and only override
-  # the release-specific fetch hashes when we need a newer stable than upstream.
-  n8n = prev.n8n.overrideAttrs (finalAttrs: previousAttrs: {
-    version = "2.29.4";
-
-    src = prev.fetchFromGitHub {
-      owner = "n8n-io";
-      repo = "n8n";
-      tag = "n8n@${finalAttrs.version}";
-      hash = "sha256-Vc10fXKn21PSlv6Sk+5zyi2efkKup1Vi+9+vyJd2I1k=";
-    };
-
-    pnpmDeps = prev.fetchPnpmDeps {
-      inherit (finalAttrs) pname version src;
-      pnpm = prev.pnpm_10;
-      fetcherVersion = 3;
-      hash = "sha256-2UFKP5bo06afaMPD+dIYQ7O0NiyZai4i8vkidi7HfxE=";
-    };
-
-    preBuild = ''
-      # Force sass-embedded to use our dart-sass instead of bundled binaries.
-      # The bundled Dart binary can't run in the Nix sandbox (no /lib64/ld-linux-x86-64.so.2).
-      for dep in node_modules/.pnpm/sass-embedded@*; do
-        substituteInPlace "$dep/node_modules/sass-embedded/dist/lib/src/compiler-path.js" \
-          --replace-fail \
-            'compilerCommand = (() => {' \
-            'compilerCommand = (() => { return ["${prev.lib.getExe prev.dart-sass}"];'
-      done
-    '';
-
-    buildPhase = ''
-      runHook preBuild
-
-      pushd node_modules/sqlite3
-      node-gyp rebuild
-      popd
-
-      # isolated-vm is a native addon required by n8n-nodes-base (Merge node SQL sandbox)
-      # since n8n 2.11.x; must be compiled before pnpm build runs generate-metadata
-      pushd node_modules/isolated-vm
-      node-gyp rebuild
-      popd
-
-      # TODO: use deploy after resolved https://github.com/pnpm/pnpm/issues/5315
-      pnpm build --filter=n8n
-
-      runHook postBuild
-    '';
-
-    meta =
-      previousAttrs.meta
-      // {
-        changelog = "https://github.com/n8n-io/n8n/releases/tag/n8n@${finalAttrs.version}";
-      };
-  });
-}

overlays/mods/n8n.nix

@@ -0,0 +1,24 @@
+{prev}:
+prev.n8n.overrideAttrs (finalAttrs: previousAttrs: {
+  version = "2.29.4";
+
+  src = prev.fetchFromGitHub {
+    owner = "n8n-io";
+    repo = "n8n";
+    tag = "n8n@${finalAttrs.version}";
+    hash = "sha256-Vc10fXKn21PSlv6Sk+5zyi2efkKup1Vi+9+vyJd2I1k=";
+  };
+
+  pnpmDeps = prev.fetchPnpmDeps {
+    inherit (finalAttrs) pname version src;
+    pnpm = prev.pnpm_10;
+    fetcherVersion = 3;
+    hash = "sha256-2UFKP5bo06afaMPD+dIYQ7O0NiyZai4i8vkidi7HfxE=";
+  };
+
+  meta =
+    previousAttrs.meta
+    // {
+      changelog = "https://github.com/n8n-io/n8n/releases/tag/n8n@${finalAttrs.version}";
+    };
+})

tests/n8n-overlay-test.nix

@@ -4,15 +4,16 @@
   self,
 }: let
   localPackages = import ../pkgs {inherit pkgs inputs;};
-  mkPkgsWithOverlay = overlay:
+  mkPkgs = overlays:
     import inputs.nixpkgs {
       system = pkgs.stdenv.hostPlatform.system;
       config.allowUnfree = true;
-      overlays = [overlay];
+      inherit overlays;
     };
 
-  modifiedPkgs = mkPkgsWithOverlay self.overlays.modifications;
+  upstreamPkgs = mkPkgs [];
-  defaultPkgs = mkPkgsWithOverlay self.overlays.default;
+  modifiedPkgs = mkPkgs [self.overlays.modifications];
+  defaultPkgs = mkPkgs [self.overlays.default];
 
   expectedVersion = "2.29.4";
   expectedSrcHash = "sha256-Vc10fXKn21PSlv6Sk+5zyi2efkKup1Vi+9+vyJd2I1k=";
@@ -29,14 +30,27 @@
     else if package.meta.changelog != expectedChangelog
     then throw "${overlayName} n8n changelog is ${package.meta.changelog}, expected ${expectedChangelog}"
     else "ok";
+
+  checkPhasesInherited = overlayName: package:
+    if (package.preBuild or null) != (upstreamPkgs.n8n.preBuild or null)
+    then throw "${overlayName} n8n preBuild should be inherited from upstream nixpkgs"
+    else if package.buildPhase != upstreamPkgs.n8n.buildPhase
+    then throw "${overlayName} n8n buildPhase should be inherited from upstream nixpkgs"
+    else "ok";
 in
   pkgs.runCommand "n8n-overlay-test" {
+    n8nOverlayFile =
+      if builtins.pathExists ../overlays/mods/n8n.nix
+      then "ok"
+      else throw "n8n overlay override must live in overlays/mods/n8n.nix";
     localN8nAbsent =
       if localPackages ? n8n
       then throw "pkgs/default.nix must not export a local n8n package"
       else "ok";
     modificationsOverlayN8n = checkN8nOverride "overlays.modifications" modifiedPkgs.n8n;
     defaultOverlayN8n = checkN8nOverride "overlays.default" defaultPkgs.n8n;
+    modificationsOverlayPhases = checkPhasesInherited "overlays.modifications" modifiedPkgs.n8n;
+    defaultOverlayPhases = checkPhasesInherited "overlays.default" defaultPkgs.n8n;
   } ''
     touch $out
   ''