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 repository
+      uses: actions/checkout@v6
+      with:
+        ref: ${{ inputs.new-release-branch }}
+        fetch-depth: 0
+        token: ${{ inputs.github-token }}
+
+    - 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
+      env:
+        NEW_RELEASE_BRANCH: ${{ inputs.new-release-branch }}
+        GITHUB_TOKEN: ${{ inputs.github-token }}
+      shell: bash
+      run: bash ./github-tools/.github/scripts/merge-previous-releases.sh
+

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

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+#!/bin/bash
+
+# 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)
+
+set -e
+
+# Parse a release branch name to extract version components
+# Returns: "major minor patch" or empty string if not valid
+parse_release_version() {
+  local branch_name="$1"
+  if [[ "$branch_name" =~ ^release/([0-9]+)\.([0-9]+)\.([0-9]+)$ ]]; then
+    echo "${BASH_REMATCH[1]} ${BASH_REMATCH[2]} ${BASH_REMATCH[3]}"
+  fi
+}
+
+# Check if version A is older than version B
+# Returns: exit code 0 if a < b, 1 otherwise
+is_version_older() {
+  local a_major="$1" a_minor="$2" a_patch="$3"
+  local b_major="$4" b_minor="$5" b_patch="$6"
+
+  if [[ "$a_major" -lt "$b_major" ]]; then return 0; fi
+  if [[ "$a_major" -gt "$b_major" ]]; then return 1; fi
+  if [[ "$a_minor" -lt "$b_minor" ]]; then return 0; fi
+  if [[ "$a_minor" -gt "$b_minor" ]]; then return 1; fi
+  if [[ "$a_patch" -lt "$b_patch" ]]; then return 0; fi
+  return 1
+}
+
+# Execute a git command and log it
+git_exec() {
+  echo "Executing: git $*"
+  git "$@"
+}
+
+# Check if a branch has already been merged into the current branch. If yes, we skip merging it again.
+# Returns: exit code 0 if merged, 1 if not merged
+is_branch_merged() {
+  local source_branch="$1"
+  git merge-base --is-ancestor "origin/${source_branch}" HEAD 2>/dev/null
+}
+
+# Merge a source branch (older release branch) into the current branch (new release branch), favoring current branch on conflicts
+merge_with_favor_destination() {
+  local source_branch="$1"
+  local dest_branch="$2"
+
+  echo ""
+  echo "============================================================"
+  echo "Merging ${source_branch} into ${dest_branch}"
+  echo "============================================================"
+
+  # Check if already merged
+  if is_branch_merged "$source_branch"; then
+    echo "Branch ${source_branch} is already merged into ${dest_branch}. Skipping."
+    return 1  # Return 1 to indicate skipped
+  fi
+
+  # Try to merge with "ours" strategy for conflicts (favors current branch (new release))
+  if git_exec merge "origin/${source_branch}" -X ours --no-edit -m "Merge ${source_branch} into ${dest_branch}"; then
+    echo "✅ Successfully merged ${source_branch} into ${dest_branch}"
+    return 0  # Return 0 to indicate merged
+  fi
+
+  # If merge still fails (shouldn't happen with -X ours, but just in case)
+  # First verify we're actually in a merge state (MERGE_HEAD exists)
+  if [[ ! -f .git/MERGE_HEAD ]]; then
+    echo "❌ Merge failed unexpectedly (no merge state). Aborting."
+    exit 1
+  fi
+
+  echo "⚠️  Merge conflict detected! Resolving by favoring destination branch (new release)..."
+
+  # First, resolve any unmerged (conflicted) files by keeping our version
+  local conflict_files
+  local conflict_count=0
+  conflict_files=$(git diff --name-only --diff-filter=U 2>/dev/null || true)
+  if [[ -n "$conflict_files" ]]; then
+    while IFS= read -r file; do
+      if [[ -n "$file" ]]; then
+        echo "  - Conflict in: ${file} → keeping destination version"
+        git_exec checkout --ours "$file"
+        git_exec add "$file"
+        ((conflict_count++)) || true
+      fi
+    done <<< "$conflict_files"
+    echo "✅ Resolved ${conflict_count} conflict(s) by keeping destination branch version"
+  fi
+
+  # Now add any remaining files (non-conflicted changes), excluding github-tools directory
+  git_exec add -- . ':!github-tools'
+
+  # Complete the merge - always commit when in merge state, even if no content changes
+  # Check if we're in a merge state (MERGE_HEAD exists)
+  if [[ -f .git/MERGE_HEAD ]]; then
+    if ! git_exec commit -m "Merge ${source_branch} into ${dest_branch}" --no-verify --allow-empty; then
+      echo "Failed to commit merge of ${source_branch}"
+      exit 1
+    fi
+  fi
+
+  echo "✅ Successfully merged ${source_branch} into ${dest_branch} (${conflict_count} conflict(s) resolved)"
+  return 0  # Return 0 to indicate merged
+}
+
+main() {
+  if [[ -z "$NEW_RELEASE_BRANCH" ]]; then
+    echo "Error: NEW_RELEASE_BRANCH environment variable is not set"
+    exit 1
+  fi
+
+  echo "New release branch: ${NEW_RELEASE_BRANCH}"
+
+  # Parse the new release version
+  local new_version
+  new_version=$(parse_release_version "$NEW_RELEASE_BRANCH")
+  if [[ -z "$new_version" ]]; then
+    echo "Error: ${NEW_RELEASE_BRANCH} is not a valid release branch (expected format: release/X.Y.Z)"
+    exit 1
+  fi
+
+  read -r new_major new_minor new_patch <<< "$new_version"
+  echo "Parsed version: ${new_major}.${new_minor}.${new_patch}"
+
+  # Fetch all remote branches
+  git_exec fetch origin
+
+  # Get all release branches
+  local all_release_branches=()
+  while IFS= read -r branch; do
+    # Remove "origin/" prefix and whitespace
+    branch="${branch#*origin/}"
+    branch="${branch// /}"
+    if [[ -n "$branch" ]] && [[ -n "$(parse_release_version "$branch")" ]]; then
+      all_release_branches+=("$branch")
+    fi
+  done < <(git branch -r --list "origin/release/*")
+
+  echo ""
+  echo "Found ${#all_release_branches[@]} release branches:"
+  for b in "${all_release_branches[@]}"; do
+    echo "  - $b"
+  done
+
+  # Filter to only branches older than the new one
+  local older_branches=()
+  for branch in "${all_release_branches[@]}"; do
+    local version
+    version=$(parse_release_version "$branch")
+    if [[ -n "$version" ]]; then
+      read -r major minor patch <<< "$version"
+      if is_version_older "$major" "$minor" "$patch" "$new_major" "$new_minor" "$new_patch"; then
+        older_branches+=("$branch")
+      fi
+    fi
+  done
+
+  # Sort older branches from oldest to newest using version sort
+  local sorted_branches=()
+  while IFS= read -r branch; do
+    [[ -n "$branch" ]] && sorted_branches+=("$branch")
+  done < <(printf '%s\n' "${older_branches[@]}" | sort -V)
+  older_branches=("${sorted_branches[@]}")
+
+  if [[ ${#older_branches[@]} -eq 0 ]]; then
+    echo ""
+    echo "No older release branches found. Nothing to merge."
+    exit 0
+  fi
+
+  echo ""
+  echo "Older release branches found (oldest to newest):"
+  for b in "${older_branches[@]}"; do
+    echo "  - $b"
+  done
+
+  echo ""
+  echo "Will merge all ${#older_branches[@]} older branches."
+
+  # Verify we're on the right branch
+  local current_branch
+  current_branch=$(git branch --show-current)
+  if [[ "$current_branch" != "$NEW_RELEASE_BRANCH" ]]; then
+    echo "Switching to ${NEW_RELEASE_BRANCH}..."
+    git_exec checkout "$NEW_RELEASE_BRANCH"
+  fi
+
+  # Merge each branch (fail fast on errors)
+  local merged_count=0
+  local skipped_count=0
+
+  for older_branch in "${older_branches[@]}"; do
+    if merge_with_favor_destination "$older_branch" "$NEW_RELEASE_BRANCH"; then
+      ((merged_count++)) || true
+    else
+      ((skipped_count++)) || true
+    fi
+  done
+
+  # Only push if we actually merged something
+  if [[ "$merged_count" -gt 0 ]]; then
+    echo ""
+    echo "Pushing merged changes..."
+    git_exec push origin "$NEW_RELEASE_BRANCH"
+  else
+    echo ""
+    echo "No new merges were made (all branches were already merged)."
+  fi
+
+  echo ""
+  echo "============================================================"
+  echo "Merge complete!"
+  echo "  Branches merged: ${merged_count}"
+  echo "  Branches skipped (already merged): ${skipped_count}"
+  echo "All source branches remain open as requested."
+  echo "============================================================"
+}
+
+# Run main and handle errors
+main "$@"