Add workflow to automatically update the bundle

.github/actions/update-bundle/action.yml

@@ -0,0 +1,14 @@
+name: Update default CodeQL bundle
+description: Updates 'src/defaults.json' to point to a new CodeQL bundle release.
+
+runs:
+  using: composite
+  steps:
+    - name: Install ts-node
+      shell: bash
+      run: npm install -g ts-node
+
+    - name: Run update script
+      working-directory: ${{ github.action_path }}
+      shell: bash
+      run: ts-node ./index.ts

.github/actions/update-bundle/index.ts

@@ -0,0 +1,64 @@
+import * as fs from 'fs';
+import * as github from '@actions/github';
+
+interface BundleInfo {
+    bundleVersion: string;
+    cliVersion: string;
+}
+
+interface Defaults {
+    bundleVersion: string;
+    cliVersion: string;
+    priorBundleVersion: string;
+    priorCliVersion: string;
+}
+
+const CODEQL_BUNDLE_PREFIX = 'codeql-bundle-';
+
+function getCodeQLCliVersionForRelease(release): string {
+    const cliVersionsFromMarkerFiles = release.assets
+      .map((asset) => asset.name.match(/cli-version-(.*)\.txt/)?.[1])
+      .filter((v) => v)
+      .map((v) => v as string);
+    if (cliVersionsFromMarkerFiles.length > 1) {
+      throw new Error(
+        `Release ${release.tag_name} has multiple CLI version marker files.`
+      );
+    } else if (cliVersionsFromMarkerFiles.length === 0) {
+      throw new Error(
+        `Failed to find the CodeQL CLI version for release ${release.tag_name}.`
+      );
+    }
+    return cliVersionsFromMarkerFiles[0];
+  }
+
+async function getBundleInfoFromRelease(release): Promise<BundleInfo> {
+    return {
+        bundleVersion: release.tag_name.substring(CODEQL_BUNDLE_PREFIX.length),
+        cliVersion: getCodeQLCliVersionForRelease(release)
+    };
+}
+
+async function getNewDefaults(currentDefaults: Defaults): Promise<Defaults> {
+    const release = github.context.payload.release;
+    console.log('Updating default bundle as a result of the following release: ' +
+        `${JSON.stringify(release)}.`)
+
+    const bundleInfo = await getBundleInfoFromRelease(release);
+    return {
+        bundleVersion: bundleInfo.bundleVersion,
+        cliVersion: bundleInfo.cliVersion,
+        priorBundleVersion: currentDefaults.bundleVersion,
+        priorCliVersion: currentDefaults.cliVersion
+    };
+}
+
+async function main() {
+  const previousDefaults: Defaults = JSON.parse(fs.readFileSync('../../../src/defaults.json', 'utf8'));
+  const newDefaults = await getNewDefaults(previousDefaults);
+  fs.writeFileSync('../../../src/defaults.json', JSON.stringify(newDefaults, null, 2) + "\n");
+}
+
+// Ideally, we'd await main() here, but that doesn't work well with `ts-node`.
+// So instead we rely on the fact that Node won't exit until the event loop is empty.
+main();

.github/workflows/update-bundle.yml

@@ -0,0 +1,82 @@
+name: Update default CodeQL bundle
+
+on:
+  release:
+    types: [prereleased]
+
+jobs:
+  update-bundle:
+    if: startsWith(github.event.release.tag_name, 'codeql-bundle-')
+    runs-on: ubuntu-latest
+    steps:
+      - name: Dump environment
+        run: env
+
+      - name: Dump GitHub context
+        env:
+          GITHUB_CONTEXT: '${{ toJson(github) }}'
+        run: echo "${GITHUB_CONTEXT}"
+
+      - uses: actions/checkout@v3
+
+      - name: Update git config
+        run: |
+          git config --global user.email "github-actions@github.com"
+          git config --global user.name "github-actions[bot]"
+
+      - name: Update bundle
+        uses: ./.github/actions/update-bundle
+
+      - name: Rebuild Action
+        run: npm run build
+
+      - name: Commit and push changes
+        env:
+          RELEASE_TAG: "${{ github.event.release.tag_name }}"
+        run: |
+          git checkout -b "update-bundle/${RELEASE_TAG}"
+          git commit -am "Update default bundle to ${RELEASE_TAG}"
+          git push --set-upstream origin "update-bundle/${RELEASE_TAG}"
+
+      - name: Open pull request
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          cli_version=$(jq -r '.cliVersion' src/defaults.json)
+          pr_url=$(gh pr create \
+            --title "Update default bundle to $cli_version" \
+            --body "This pull request updates the default CodeQL bundle, as used with \`tools: latest\` and on GHES, to $cli_version." \
+            --assignee "${GITHUB_ACTOR}" \
+            --draft \
+          )
+          echo "CLI_VERSION=$cli_version" >> $GITHUB_ENV
+          echo "PR_URL=$pr_url" >> $GITHUB_ENV
+
+      - name: Create changelog note
+        shell: python
+        run: |
+          import os
+          import re
+
+          # Get the PR number from the PR URL.
+          pr_number = os.environ['PR_URL'].split('/')[-1]
+          changelog_note = f"- Update default CodeQL bundle version to {os.environ['CLI_VERSION']}. [#{pr_number}]({os.environ['PR_URL']})"
+
+          # If the "[UNRELEASED]" section starts with "no user facing changes", remove that line.
+          # Use perl to avoid having to escape the newline character.
+
+          with open('CHANGELOG.md', 'r') as f:
+              changelog = f.read()
+
+          changelog = changelog.replace('## [UNRELEASED]\n\nNo user facing changes.', '## [UNRELEASED]\n')
+
+          # Add the changelog note to the bottom of the "[UNRELEASED]" section.
+          changelog = re.sub(r'\n## (\d+\.\d+\.\d+)', f'{changelog_note}\n\n## \\1', changelog, count=1)
+
+          with open('CHANGELOG.md', 'w') as f:
+              f.write(changelog)
+
+      - name: Push changelog note
+        run: |
+          git commit -am "Add changelog note"
+          git push