From 5477cfc71b6c7e3843cdacc202c904fcfb3a5e52 Mon Sep 17 00:00:00 2001
From: m3tam3re <p@m3ta.dev>
Date: Sun, 26 Jul 2026 12:09:22 +0200
Subject: [PATCH] feat: add automatic n8n overlay updates
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- overlays/mods/n8n.nix: add passthru.updateScript pointing to ./update.sh
- overlays/mods/update.sh: self-contained updater that fetches the latest
  stable n8n-io/n8n release, recomputes both src and pnpmDeps hashes
  (src via nix-prefetch-url with --name workaround for the `@` in the tag,
  pnpmDeps via the lib.fakeHash mismatch trick)
- .gitea/workflows/nix-update.yml: discover and run overlays/mods/*/update.sh
  after the pkgs/ loop; verify step skips overlay/* entries (covered by flake check)

The test suite (tests/n8n-overlay-test.nix) forbids exporting a local n8n
package, so the overlay cannot be exposed via pkgs/n8n/ — the workflow gets
an explicit overlay-discovery block instead.
---
 .gitea/workflows/nix-update.yml |  47 ++++++++++
 overlays/mods/n8n.nix           |   5 ++
 overlays/mods/update.sh         | 153 ++++++++++++++++++++++++++++++++
 3 files changed, 205 insertions(+)
 create mode 100755 overlays/mods/update.sh

diff --git a/.gitea/workflows/nix-update.yml b/.gitea/workflows/nix-update.yml
index 332b429..9bea6ce 100644
--- a/.gitea/workflows/nix-update.yml
+++ b/.gitea/workflows/nix-update.yml
@@ -352,6 +352,47 @@ jobs:
             done
           fi
 
+          # ── Update overlay modifications (overlays/mods/) ───────────────
+          # Overlay updates live outside pkgs/ because the test suite
+          # (tests/n8n-overlay-test.nix) forbids exporting the overlay target
+          # as a local package. Each `overlays/mods/*/update.sh` or
+          # `overlays/mods/update.sh` is a self-contained updater that handles
+          # version discovery, hash recomputation, and commit on its own.
+          if [ -z "${{ inputs.package }}" ]; then
+            echo ""
+            echo "🔍 Discovering overlay update scripts in overlays/mods/ ..."
+            OVERLAY_SCRIPTS=$(find overlays/mods -maxdepth 2 -name "update.sh" 2>/dev/null | sort)
+
+            if [ -n "$OVERLAY_SCRIPTS" ]; then
+              for script in $OVERLAY_SCRIPTS; do
+                OVERLAY_NAME=$(basename "$(dirname "$script")")
+                echo "::group::Updating overlay: $OVERLAY_NAME"
+                BEFORE_HASH=$(git rev-parse HEAD)
+
+                # Overlay scripts are self-contained and use nix-shell shebangs
+                # for their dependencies. They commit on their own.
+                if bash "$script" 2>&1 | tee /tmp/update-overlay-${OVERLAY_NAME}.log; then
+                  if [ "$(git rev-parse HEAD)" != "$BEFORE_HASH" ]; then
+                    echo "✅ Updated overlay/$OVERLAY_NAME"
+                    UPDATES_FOUND=true
+                    if [ -n "$UPDATED_PACKAGES" ]; then
+                      UPDATED_PACKAGES="$UPDATED_PACKAGES, overlay/$OVERLAY_NAME"
+                    else
+                      UPDATED_PACKAGES="overlay/$OVERLAY_NAME"
+                    fi
+                  else
+                    echo "✓ overlay/$OVERLAY_NAME already up to date"
+                  fi
+                else
+                  echo "⚠️ Update failed for overlay/$OVERLAY_NAME"
+                fi
+                echo "::endgroup::"
+              done
+            else
+              echo "ℹ️ No overlay update scripts found."
+            fi
+          fi
+
           COMMIT_COUNT=$(git rev-list --count origin/master..HEAD)
 
           if [ "$COMMIT_COUNT" -gt 0 ]; then
@@ -382,6 +423,12 @@ jobs:
           SUCCESSFUL_PACKAGES=()
 
           for pkg in "${PKGS[@]}"; do
+            # Overlay updates (e.g. "overlay/n8n") have no top-level flake
+            # attribute — `nix flake check` already verifies them above.
+            if [[ "$pkg" == overlay/* ]]; then
+              echo "⊘ Skipping per-package build for $pkg (verified via flake check)"
+              continue
+            fi
             echo "::group::Building $pkg"
             if nix build .#$pkg 2>&1 | tee /tmp/build-${pkg}.log; then
               echo "✅ Build successful for $pkg"
diff --git a/overlays/mods/n8n.nix b/overlays/mods/n8n.nix
index 8334ccb..510402b 100644
--- a/overlays/mods/n8n.nix
+++ b/overlays/mods/n8n.nix
@@ -39,6 +39,11 @@ in
         fi
       '';
 
+    # Self-contained update script (./update.sh) — fetches latest stable
+    # release from n8n-io/n8n, recomputes both src and pnpmDeps hashes.
+    # The CI workflow in .gitea/workflows/nix-update.yml discovers and runs it.
+    passthru = (previousAttrs.passthru or {}) // {updateScript = ./update.sh;};
+
     meta =
       previousAttrs.meta
       // {
diff --git a/overlays/mods/update.sh b/overlays/mods/update.sh
new file mode 100755
index 0000000..63d4b8d
--- /dev/null
+++ b/overlays/mods/update.sh
@@ -0,0 +1,153 @@
+#!/usr/bin/env nix-shell
+#!nix-shell --pure -i bash -p bash curl jq nix nix-prefetch cacert git
+set -euo pipefail
+
+# Update the n8n overlay (overlays/mods/n8n.nix) to the latest stable GitHub
+# release of n8n-io/n8n.
+#
+# This is a self-contained updater (not nix-update), because the overlay file
+# is a `prev.n8n.overrideAttrs` form rather than a standalone derivation and
+# the test suite (tests/n8n-overlay-test.nix) explicitly forbids exporting a
+# local n8n package. The CI workflow discovers and runs this script directly.
+#
+# What it does, in order:
+#   1. Fetch latest stable (non-prerelease) tag from the GitHub API
+#   2. Strip the `n8n@` prefix → version
+#   3. Compare to the version pinned in overlays/mods/n8n.nix
+#   4. Compute new src hash (fetchFromGitHub tarball) via nix-prefetch-url
+#   5. Compute new pnpmDeps hash via the lib.fakeHash trick
+#   6. Commit
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+NIX_FILE="$SCRIPT_DIR/n8n.nix"
+
+REPO="n8n-io/n8n"
+TAG_PREFIX="n8n@"
+
+# ── 1. Latest stable release ───────────────────────────────────────────────
+echo "Fetching latest stable release of $REPO ..."
+LATEST_TAG=$(curl -fsSL "https://api.github.com/repos/$REPO/releases/latest" \
+  | jq -r 'select(.prerelease == false) | .tag_name')
+
+if [[ -z "$LATEST_TAG" ]]; then
+  echo "ERROR: No stable release found for $REPO" >&2
+  exit 1
+fi
+
+VERSION="${LATEST_TAG#${TAG_PREFIX}}"
+echo "Latest version: $VERSION"
+
+# ── 2. Current version from the nix file ───────────────────────────────────
+CURRENT=$(awk '
+  /^[[:space:]]*version = "/ {
+    gsub(/^[[:space:]]*version = "/, "")
+    gsub(/".*/, "")
+    print
+    exit
+  }
+' "$NIX_FILE")
+echo "Current version: $CURRENT"
+
+if [[ "$VERSION" == "$CURRENT" ]]; then
+  echo "Already at latest version, nothing to do."
+  exit 0
+fi
+
+echo "==> Updating n8n $CURRENT -> $VERSION"
+
+# ── 3. Bump version in the file ────────────────────────────────────────────
+sed -i "s|^\([[:space:]]*\)version = \"[^\"]*\";|\1version = \"$VERSION\";|" "$NIX_FILE"
+
+# ── 4. Compute and apply src hash ──────────────────────────────────────────
+echo "==> Computing src hash ..."
+SRC_URL="https://github.com/$REPO/archive/refs/tags/${TAG_PREFIX}${VERSION}.tar.gz"
+# `--name n8n-source` works around the `@` in the upstream tag name
+# (nix-prefetch-url refuses filenames containing `@`).
+SRC_HASH=$(nix-prefetch-url --unpack --type sha256 --name n8n-source "$SRC_URL" 2>/dev/null)
+SRC_SRI=$(nix hash convert --hash-algo sha256 --to sri "$SRC_HASH")
+echo "    src hash: $SRC_SRI"
+
+# Replace the FIRST `hash = "sha256-...";` occurrence (the src block sits above pnpmDeps)
+awk -v sri="$SRC_SRI" '
+  !src_done && /^[[:space:]]*hash = "sha256-/ {
+    sub(/"sha256-[A-Za-z0-9+/=]+"/, "\"" sri "\"")
+    src_done = 1
+  }
+  { print }
+' "$NIX_FILE" > "$NIX_FILE.tmp" && mv "$NIX_FILE.tmp" "$NIX_FILE"
+
+# ── 5. Compute pnpmDeps hash via lib.fakeHash ──────────────────────────────
+echo "==> Computing pnpmDeps hash (this may take a while) ..."
+
+# 5a. Temporarily set the pnpmDeps hash to lib.fakeHash
+awk '
+  !pnpm_started && /^[[:space:]]*pnpmDeps = / { pnpm_started = 1 }
+  pnpm_started && !pnpm_done && /^[[:space:]]*hash = "sha256-/ {
+    sub(/"sha256-[A-Za-z0-9+/=]+"/, "lib.fakeHash")
+    pnpm_done = 1
+  }
+  { print }
+' "$NIX_FILE" > "$NIX_FILE.tmp" && mv "$NIX_FILE.tmp" "$NIX_FILE"
+
+# 5b. Evaluate n8nModified.pnpmDeps — fixed-output derivation with a wrong hash
+#     will fail and print the correct hash in the "got:" line.
+SYSTEM=$(nix eval --impure --raw --expr 'builtins.currentSystem' 2>/dev/null || echo "x86_64-linux")
+NIX_EXPR="(let
+    flake = builtins.getFlake (toString ./.);
+    pkgs = flake.inputs.nixpkgs.legacyPackages.\${builtins.currentSystem};
+    n8nModified = import ./overlays/mods/n8n.nix { prev = pkgs; };
+  in n8nModified.pnpmDeps)"
+
+BUILD_OUTPUT=$(nix build --impure --no-link --expr "$NIX_EXPR" 2>&1 || true)
+
+# Hash mismatch errors list two sha256 values: the wrong "Expected"/"specified"
+# one (our lib.fakeHash = all A's) and the correct "Got"/"got" one. Different
+# nix versions capitalise the label differently, so we filter out the fakeHash
+# sentinel and take whatever real sha256 remains.
+PNPM_HASH=$(echo "$BUILD_OUTPUT" \
+  | grep -oE 'sha256-[A-Za-z0-9+/=]+' \
+  | grep -v 'AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA' \
+  | tail -1)
+
+if [[ -z "$PNPM_HASH" ]]; then
+  echo "ERROR: Failed to compute pnpmDeps hash. nix build output:" >&2
+  echo "$BUILD_OUTPUT" >&2
+  echo "Restoring original file..." >&2
+  git checkout -- "$NIX_FILE" 2>/dev/null || true
+  exit 1
+fi
+
+echo "    pnpmDeps hash: $PNPM_HASH"
+
+# 5d. Replace lib.fakeHash with the real hash
+awk -v sri="$PNPM_HASH" '
+  !pnpm_started && /^[[:space:]]*pnpmDeps = / { pnpm_started = 1 }
+  pnpm_started && !pnpm_done && /^[[:space:]]*hash = / {
+    sub(/lib\.fakeHash/, "\"" sri "\"")
+    pnpm_done = 1
+  }
+  { print }
+' "$NIX_FILE" > "$NIX_FILE.tmp" && mv "$NIX_FILE.tmp" "$NIX_FILE"
+
+# ── 6. Verify the file parses and commit ───────────────────────────────────
+echo "==> Verifying nix evaluation ..."
+if ! nix eval --impure --expr "
+  let
+    flake = builtins.getFlake (toString ./.);
+    pkgs = flake.inputs.nixpkgs.legacyPackages.\${builtins.currentSystem};
+  in (import ./overlays/mods/n8n.nix { prev = pkgs; }).version
+" >/dev/null 2>&1; then
+  echo "ERROR: nix evaluation failed after update; restoring original." >&2
+  git checkout -- "$NIX_FILE" 2>/dev/null || true
+  exit 1
+fi
+
+NIXPKGS_ROOT=$(git -C "$SCRIPT_DIR" rev-parse --show-toplevel 2>/dev/null || true)
+if [[ -n "$NIXPKGS_ROOT" ]] && \
+   [[ -n "$(git -C "$NIXPKGS_ROOT" status --porcelain "$NIX_FILE")" ]]; then
+  git -C "$NIXPKGS_ROOT" add "$NIX_FILE"
+  git -C "$NIXPKGS_ROOT" commit -m "n8n: $CURRENT -> $VERSION"
+  echo "==> Committed"
+fi
+
+echo "==> Done"