INFRA-3187: Automate Merging Release Branch workflow

.github/actions/merge-previous-releases/action.yml

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+name: Merge Previous Releases
+description: 'An action to merge previous release branches into a newly created release branch.'
+
+inputs:
+  new-release-branch:
+    required: true
+    description: 'The newly created release branch (e.g., release/2.1.2)'
+  github-token:
+    description: 'GitHub token used for authentication.'
+    required: true
+  github-tools-repository:
+    description: 'The GitHub repository containing the GitHub tools. Defaults to the GitHub tools action repository, and usually does not need to be changed.'
+    required: false
+    default: ${{ github.action_repository }}
+  github-tools-ref:
+    description: 'The SHA of the action to use. Defaults to the current action ref, and usually does not need to be changed.'
+    required: false
+    default: ${{ github.action_ref }}
+
+runs:
+  using: composite
+  steps:
+    - name: Checkout GitHub tools repository
+      uses: actions/checkout@v6
+      with:
+        repository: ${{ inputs.github-tools-repository }}
+        ref: ${{ inputs.github-tools-ref }}
+        path: ./github-tools
+
+    - name: Set Git user and email
+      shell: bash
+      run: |
+        git config --global user.name "github-actions[bot]"
+        git config --global user.email "github-actions[bot]@users.noreply.github.com"
+
+    - name: Run merge previous releases script
+      id: merge-releases
+      env:
+        NEW_RELEASE_BRANCH: ${{ inputs.new-release-branch }}
+        GITHUB_TOKEN: ${{ inputs.github-token }}
+      shell: bash
+      run: |
+        # Ensure github-tools is in .gitignore to prevent it from being committed
+        if ! grep -q "^github-tools/" .gitignore 2>/dev/null; then
+          echo "github-tools/" >> .gitignore
+          echo "Added github-tools/ to .gitignore"
+        fi
+
+        # Execute the script from github-tools
+        bash ./github-tools/.github/scripts/merge-previous-releases.sh

.github/scripts/merge-previous-releases.js

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+#!/usr/bin/env node
+
+/**
+ * Merge Previous Release Branches Script
+ *
+ * This script is triggered when a new release branch is created (e.g., release/2.1.2).
+ * It finds all previous release branches and merges them into the new release branch.
+ *
+ * Key behaviors:
+ * - Merges ALL older release branches into the new one
+ * - For merge conflicts, favors the destination branch (new release)
+ * - Both branches remain open after merge
+ * - Fails fast on errors to prevent pushing partial merges
+ *
+ * Environment variables:
+ * - NEW_RELEASE_BRANCH: The newly created release branch (e.g., release/2.1.2)
+ */
+
+const { promisify } = require('util');
+const exec = promisify(require('child_process').exec);
+
+/**
+ * Parse a release branch name to extract version components
+ * @param {string} branchName - Branch name like "release/2.1.2"
+ * @returns {object|null} - { major, minor, patch } or null if not a valid release branch
+ */
+function parseReleaseVersion(branchName) {
+  // Match release/X.Y.Z format (does not match release candidates like release/2.1.2-rc.1)
+  const match = branchName.match(/^release\/(\d+)\.(\d+)\.(\d+)$/);
+  if (!match) {
+    return null;
+  }
+  return {
+    major: parseInt(match[1], 10),
+    minor: parseInt(match[2], 10),
+    patch: parseInt(match[3], 10),
+  };
+}
+
+/**
+ * Compare two version objects
+ * @returns {number} - negative if a < b, positive if a > b, 0 if equal
+ */
+function compareVersions(a, b) {
+  if (a.major !== b.major) return a.major - b.major;
+  if (a.minor !== b.minor) return a.minor - b.minor;
+  return a.patch - b.patch;
+}
+
+/**
+ * Execute a git command and log it
+ */
+async function gitExec(command, options = {}) {
+  const { ignoreError = false } = options;
+  console.log(`Executing: git ${command}`);
+  try {
+    const { stdout, stderr } = await exec(`git ${command}`);
+    if (stdout.trim()) console.log(stdout.trim());
+    if (stderr.trim()) console.log(stderr.trim());
+    return { stdout, stderr, success: true };
+  } catch (error) {
+    if (ignoreError) {
+      console.warn(`Warning: ${error.message}`);
+      return { stdout: error.stdout, stderr: error.stderr, success: false, error };
+    }
+    throw error;
+  }
+}
+
+/**
+ * Get all remote release branches
+ */
+async function getReleaseBranches() {
+  await gitExec('fetch origin');
+  const { stdout } = await exec('git branch -r --list "origin/release/*"');
+  return stdout
+    .split('\n')
+    .map((branch) => branch.trim().replace('origin/', ''))
+    .filter((branch) => branch && parseReleaseVersion(branch));
+}
+
+/**
+ * Check if a branch has already been merged into the current branch. If yes, skip the merge.
+ * @param {string} sourceBranch - The branch to check if it has already been merged into the current branch
+ * @returns {Promise<boolean>} - True if the branch has already been merged into the current branch, false otherwise
+ */
+async function isBranchMerged(sourceBranch) {
+  try {
+    // Check if the source branch's HEAD is an ancestor of current HEAD
+    const { stdout } = await exec(
+      `git merge-base --is-ancestor origin/${sourceBranch} HEAD && echo "merged" || echo "not-merged"`,
+    );
+    return stdout.trim() === 'merged';
+  } catch {
+    // If the command fails, assume not merged
+    return false;
+  }
+}
+
+/**
+ * Merge a source branch into the current branch, favoring current branch on conflicts
+ * Uses approach similar to stable-sync.js
+ */
+async function mergeWithFavorDestination(sourceBranch, destBranch) {
+  console.log(`\n${'='.repeat(60)}`);
+  console.log(`Merging ${sourceBranch} into ${destBranch}`);
+  console.log('='.repeat(60));
+
+  // Check if already merged
+  const alreadyMerged = await isBranchMerged(sourceBranch);
+  if (alreadyMerged) {
+    console.log(`Branch ${sourceBranch} is already merged into ${destBranch}. Skipping.`);
+    return { skipped: true };
+  }
+
+  // Try to merge with "ours" strategy for conflicts (favors current branch)
+  const mergeResult = await gitExec(
+    `merge origin/${sourceBranch} -X ours --no-edit -m "Merge ${sourceBranch} into ${destBranch}"`,
+    { ignoreError: true },
+  );
+
+  if (!mergeResult.success) {
+    // If merge still fails (shouldn't happen with -X ours, but just in case)
+    console.log('Merge had conflicts, resolving by favoring destination branch...');
+
+    // Add all files and resolve conflicts by keeping destination version
+    await gitExec('add .');
+
+    // For any remaining conflicts, checkout our version
+    try {
+      const { stdout: conflictFiles } = await exec('git diff --name-only --diff-filter=U');
+      if (conflictFiles.trim()) {
+        for (const file of conflictFiles.trim().split('\n')) {
+          if (file) {
+            console.log(`Resolving conflict in ${file} by keeping destination version`);
+            await gitExec(`checkout --ours "${file}"`);
+            await gitExec(`add "${file}"`);
+          }
+        }
+      }
+    } catch (e) {
+      // No conflicts to resolve
+    }
+
+    // Complete the merge
+    const { stdout: status } = await exec('git status --porcelain');
+    if (status.trim()) {
+      const commitResult = await gitExec(
+        `commit -m "Merge ${sourceBranch} into ${destBranch}" --no-verify`,
+        { ignoreError: true },
+      );
+      if (!commitResult.success) {
+        throw new Error(`Failed to commit merge of ${sourceBranch}: ${commitResult.error?.message}`);
+      }
+    }
+  }
+
+  console.log(`Successfully merged ${sourceBranch} into ${destBranch}`);
+  return { skipped: false };
+}
+
+async function main() {
+  const newReleaseBranch = process.env.NEW_RELEASE_BRANCH;
+
+  if (!newReleaseBranch) {
+    console.error('Error: NEW_RELEASE_BRANCH environment variable is not set');
+    process.exit(1);
+  }
+
+  console.log(`New release branch: ${newReleaseBranch}`);
+
+  const newVersion = parseReleaseVersion(newReleaseBranch);
+  if (!newVersion) {
+    console.error(
+      `Error: ${newReleaseBranch} is not a valid release branch (expected format: release/X.Y.Z)`,
+    );
+    process.exit(1);
+  }
+
+  console.log(`Parsed version: ${newVersion.major}.${newVersion.minor}.${newVersion.patch}`);
+
+  // Get all release branches
+  const allReleaseBranches = await getReleaseBranches();
+  console.log(`\nFound ${allReleaseBranches.length} release branches:`);
+  allReleaseBranches.forEach((b) => console.log(`  - ${b}`));
+
+  // Filter to only branches older than the new one, sorted from oldest to newest
+  const olderBranches = allReleaseBranches
+    .filter((branch) => {
+      const version = parseReleaseVersion(branch);
+      return version && compareVersions(version, newVersion) < 0;
+    })
+    .sort((a, b) => {
+      const versionA = parseReleaseVersion(a);
+      const versionB = parseReleaseVersion(b);
+      return compareVersions(versionA, versionB);
+    });
+
+  if (olderBranches.length === 0) {
+    console.log('\nNo older release branches found. Nothing to merge.');
+    return;
+  }
+
+  console.log(`\nOlder release branches found (oldest to newest):`);
+  olderBranches.forEach((b) => console.log(`  - ${b}`));
+
+  // Merge all older branches
+  const branchesToMerge = olderBranches;
+  console.log(`\nWill merge all ${branchesToMerge.length} older branches.`);
+
+  // We should already be on the new release branch (checkout was done in the workflow)
+  // But let's verify and ensure we're on the right branch
+  const { stdout: currentBranch } = await exec('git branch --show-current');
+  if (currentBranch.trim() !== newReleaseBranch) {
+    console.log(`Switching to ${newReleaseBranch}...`);
+    await gitExec(`checkout ${newReleaseBranch}`);
+  }
+
+  // Merge each branch (fail fast on errors)
+  let mergedCount = 0;
+  let skippedCount = 0;
+
+  for (const olderBranch of branchesToMerge) {
+    const result = await mergeWithFavorDestination(olderBranch, newReleaseBranch);
+    if (result.skipped) {
+      skippedCount++;
+    } else {
+      mergedCount++;
+    }
+  }
+
+  // Only push if we actually merged something
+  if (mergedCount > 0) {
+    console.log('\nPushing merged changes...');
+    await gitExec(`push origin ${newReleaseBranch}`);
+  } else {
+    console.log('\nNo new merges were made (all branches were already merged).');
+  }
+
+  console.log('\n' + '='.repeat(60));
+  console.log('Merge complete!');
+  console.log(`  Branches merged: ${mergedCount}`);
+  console.log(`  Branches skipped (already merged): ${skippedCount}`);
+  console.log(`All source branches remain open as requested.`);
+  console.log('='.repeat(60));
+}
+
+main().catch((error) => {
+  console.error(`\nFatal error: ${error.message}`);
+  console.error('Aborting to prevent pushing partial merges.');
+  process.exit(1);
+});