Add build plugin to check Node versions

.github/workflows/pr-checks.yml

@@ -105,42 +105,51 @@ jobs:
         run: npx tsx --test
 
   check-node-version:
-    if: github.triggering_actor != 'dependabot[bot]'
-    name: Check Action Node versions
+    if: github.triggering_actor != 'dependabot[bot]' && startsWith(github.head_ref, 'backport-')
+    name: Check Action Node versions for Backport
     runs-on: ubuntu-latest
-    timeout-minutes: 45
+    timeout-minutes: 5
     env:
       BASE_REF: ${{ github.base_ref }}
 
     permissions:
       contents: read
 
     steps:
-      - uses: actions/checkout@v6
+      - name: Checkout repository
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 1
+
       - id: head-version
-        name: Verify all Actions use the same Node version
+        name: Determine Node version for HEAD
         run: |
-          NODE_VERSION=$(find . -name "action.yml" -exec yq -e '.runs.using' {} \; | grep node | sort | uniq)
-          echo "NODE_VERSION: ${NODE_VERSION}"
-          if [[ $(echo "$NODE_VERSION" | wc -l) -gt 1 ]]; then
-            echo "::error::More than one node version used in 'action.yml' files."
+          if [[ ! -f ".nvmrc" ]]; then
+            echo "::error::Cannot find .nvmrc in the HEAD commit."
             exit 1
           fi
+
+          NODE_VERSION=$(cat .nvmrc)
+          echo "NODE_VERSION: ${NODE_VERSION}"
           echo "node_version=${NODE_VERSION}" >> $GITHUB_OUTPUT
 
       - id: checkout-base
         name: 'Backport: Check out base ref'
-        if: ${{ startsWith(github.head_ref, 'backport-') }}
         uses: actions/checkout@v6
         with:
           ref: ${{ env.BASE_REF }}
+          fetch-depth: 1
 
       - name: 'Backport: Verify Node versions unchanged'
-        if: steps.checkout-base.outcome == 'success'
         env:
           HEAD_VERSION: ${{ steps.head-version.outputs.node_version }}
         run: |
-          BASE_VERSION=$(find . -name "action.yml" -exec yq -e '.runs.using' {} \; | grep node | sort | uniq)
+          if [[ ! -f ".nvmrc" ]]; then
+            echo "::error::Cannot find .nvmrc in the base commit."
+            exit 1
+          fi
+
+          BASE_VERSION=$(cat .nvmrc)
           echo "HEAD_VERSION: ${HEAD_VERSION}"
           echo "BASE_VERSION: ${BASE_VERSION}"
           if [[ "$BASE_VERSION" != "$HEAD_VERSION" ]]; then

.nvmrc

@@ -0,0 +1 @@
+24

build.mjs

@@ -4,6 +4,7 @@ import { fileURLToPath } from "node:url";
 
 import * as esbuild from "esbuild";
 import { globSync } from "glob";
+import * as yaml from "js-yaml";
 
 import pkg from "./package.json" with { type: "json" };
 
@@ -27,6 +28,70 @@ const cleanPlugin = {
   },
 };
 
+/** A plugin that checks that the Node versions in all `action.yml` files are the same. */
+const checkNodeVersionsPlugin = {
+  name: "check-node-versions",
+  setup(build) {
+    build.onStart(async () => {
+      // Find all the `action.yml` files. We don't care about the stub in the repository root,
+      // since that is a `composite` action.
+      const actionSpecifications = globSync("*/action.yml");
+
+      // Track the Node versions we find for each file.
+      const nodeVersions = {};
+
+      // We will store the first Node version we find and use it to compare against the others.
+      // If there's any disagreement, we set `versionMismatch` to `true` and throw an error
+      // that includes all the discovered Node versions at the end.
+      let nodeVersion = undefined;
+      let versionMismatch = false;
+
+      for (const actionSpecification of actionSpecifications) {
+        // Read the contents of the action.yml file.
+        const contents = await readFile(actionSpecification, "utf-8");
+        const specification = yaml.load(contents);
+
+        // Find the `runs.using` value in the specification.
+        const using = specification.runs.using;
+        if (using === undefined || using === null) {
+          throw new Error(
+            `Couldn't find 'runs.using' in ${actionSpecification}`,
+          );
+        }
+
+        if (typeof using !== "string" || !using.startsWith("node")) {
+          throw new Error(
+            `Expected 'runs.using' to be a string starting with 'node' in ${actionSpecification}`,
+          );
+        }
+
+        if (nodeVersion === undefined) {
+          // First one we found: set it as the baseline.
+          nodeVersion = using;
+        } else if (nodeVersion !== using) {
+          // Disagreement: set `versionMismatch` to indicate that we should throw an error later.
+          versionMismatch = true;
+        }
+        nodeVersions[actionSpecification] = using;
+      }
+
+      // Throw an error if there was a version mismatch.
+      if (versionMismatch) {
+        throw new Error(
+          `More than one node version used in 'action.yml' files: ${JSON.stringify(nodeVersions)}`,
+        );
+      }
+
+      // Write the node version to `.nvmrc`.
+      await writeFile(
+        join(__dirname, ".nvmrc"),
+        nodeVersion.substring("node".length) + "\n",
+        "utf-8",
+      );
+    });
+  },
+};
+
 /**
  * Copy defaults.json to the output directory since other projects depend on it.
  *
@@ -78,7 +143,7 @@ const UPLOAD_LIB_SRC = "./src/upload-lib";
  *
  * The virtual module additionally re-exports `upload-lib` under the `uploadLib` namespace so that
  * external consumers can access it via the small `lib/upload-lib.js` stub emitted below.
- * 
+ *
  * A tiny stub file is emitted for each Action entrypoint, and one for `upload-lib`. Each stub
  * imports the shared bundle and calls/re-exports from the respective entry point.
  *
@@ -208,7 +273,13 @@ const context = await esbuild.context({
   outdir: OUT_DIR,
   platform: "node",
   external: ["./entry-points"],
-  plugins: [cleanPlugin, copyDefaultsPlugin, entryPointsPlugin, onEndPlugin],
+  plugins: [
+    cleanPlugin,
+    checkNodeVersionsPlugin,
+    copyDefaultsPlugin,
+    entryPointsPlugin,
+    onEndPlugin,
+  ],
   target: ["node20"],
   define: {
     __CODEQL_ACTION_VERSION__: JSON.stringify(pkg.version),