.github/update-release-branch.py

@@ -19,15 +19,19 @@
 # Value of the mode flag for a v2 release
 V2_MODE = 'v2-release'
 
+SOURCE_BRANCH_FOR_MODE = { V1_MODE: 'releases/v2', V2_MODE: 'main' }
+TARGET_BRANCH_FOR_MODE = { V1_MODE: 'releases/v1', V2_MODE: 'releases/v2' }
+
 # Name of the remote
 ORIGIN = 'origin'
 
 # Runs git with the given args and returns the stdout.
-# Raises an error if git does not exit successfully.
-def run_git(*args):
+# Raises an error if git does not exit successfully (unless passed
+# allow_non_zero_exit_code=True).
+def run_git(*args, allow_non_zero_exit_code=False):
   cmd = ['git', *args]
   p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-  if (p.returncode != 0):
+  if not allow_non_zero_exit_code and p.returncode != 0:
     raise Exception('Call to ' + ' '.join(cmd) + ' exited with code ' + str(p.returncode) + ' stderr:' + p.stderr.decode('ascii'))
   return p.stdout.decode('ascii')
 
@@ -36,7 +40,9 @@ def branch_exists_on_remote(branch_name):
   return run_git('ls-remote', '--heads', ORIGIN, branch_name).strip() != ''
 
 # Opens a PR from the given branch to the target branch
-def open_pr(repo, all_commits, source_branch_short_sha, new_branch_name, source_branch, target_branch, conductor, is_v2_release, labels):
+def open_pr(
+  repo, all_commits, source_branch_short_sha, new_branch_name, source_branch, target_branch,
+  conductor, is_v2_release, labels, conflicted_files):
   # Sort the commits into the pull requests that introduced them,
   # and any commits that don't have a pull request
   pull_requests = []
@@ -81,6 +87,12 @@ def open_pr(repo, all_commits, source_branch_short_sha, new_branch_name, source_
 
   body.append('')
   body.append('Please review the following:')
+  if len(conflicted_files) > 0:
+    body.append(' - [ ] You have added commits to this branch that resolve the merge conflicts ' +
+      'in the following files:')
+    body.extend([f'    - [ ] `{file}`' for file in conflicted_files])
+    body.append(' - [ ] Another maintainer has reviewed the additional commits you added to this ' +
+      'branch to resolve the merge conflicts.')
   body.append(' - [ ] The CHANGELOG displays the correct version and date.')
   body.append(' - [ ] The CHANGELOG includes all relevant, user-facing changes since the last release.')
   body.append(' - [ ] There are no unexpected commits being merged into the ' + target_branch + ' branch.')
@@ -191,8 +203,10 @@ def main():
     type=str,
     required=True,
     choices=[V2_MODE, V1_MODE],
-    help=f"Which release to perform. '{V2_MODE}' uses main as the source branch and v2 as the target branch. " +
-      f"'{V1_MODE}' uses v2 as the source branch and v1 as the target branch."
+    help=f"Which release to perform. '{V2_MODE}' uses {SOURCE_BRANCH_FOR_MODE[V2_MODE]} as the source " +
+      f"branch and {TARGET_BRANCH_FOR_MODE[V2_MODE]} as the target branch. " +
+      f"'{V1_MODE}' uses {SOURCE_BRANCH_FOR_MODE[V1_MODE]} as the source branch and " +
+      f"{TARGET_BRANCH_FOR_MODE[V1_MODE]} as the target branch."
   )
   parser.add_argument(
     '--conductor',
@@ -203,14 +217,8 @@ def main():
 
   args = parser.parse_args()
 
-  if args.mode == V2_MODE:
-    source_branch = 'main'
-    target_branch = 'v2'
-  elif args.mode == V1_MODE:
-    source_branch = 'v2'
-    target_branch = 'v1'
-  else:
-    raise ValueError(f"Unexpected value for release mode: '{args.mode}'")
+  source_branch = SOURCE_BRANCH_FOR_MODE[args.mode]
+  target_branch = TARGET_BRANCH_FOR_MODE[args.mode]
 
   repo = Github(args.github_token).get_repo(args.repository_nwo)
   version = get_current_version()
@@ -246,10 +254,15 @@ def main():
   # Create the new branch and push it to the remote
   print('Creating branch ' + new_branch_name)
 
+  # The process of creating the v1 release can run into merge conflicts. We commit the unresolved
+  # conflicts so a maintainer can easily resolve them (vs erroring and requiring maintainers to
+  # reconstruct the release manually)
+  conflicted_files = []
+
   if args.mode == V1_MODE:
-    # If we're performing a backport, start from the v1 branch
-    print(f'Creating {new_branch_name} from the {ORIGIN}/v1 branch')
-    run_git('checkout', '-b', new_branch_name, f'{ORIGIN}/v1')
+    # If we're performing a backport, start from the target branch
+    print(f'Creating {new_branch_name} from the {ORIGIN}/{target_branch} branch')
+    run_git('checkout', '-b', new_branch_name, f'{ORIGIN}/{target_branch}')
 
     # Revert the commit that we made as part of the last release that updated the version number and
     # changelog to refer to 1.x.x variants. This avoids merge conflicts in the changelog and
@@ -274,7 +287,12 @@ def main():
       print('  Nothing to revert.')
 
     print(f'Merging {ORIGIN}/{source_branch} into the release prep branch')
-    run_git('merge', f'{ORIGIN}/{source_branch}', '--no-edit')
+    # Commit any conflicts (see the comment for `conflicted_files`)
+    run_git('merge', f'{ORIGIN}/{source_branch}', allow_non_zero_exit_code=True)
+    conflicted_files = run_git('diff', '--name-only', '--diff-filter', 'U').splitlines()
+    if len(conflicted_files) > 0:
+      run_git('add', '.')
+    run_git('commit', '--no-edit')
 
     # Migrate the package version number from a v2 version number to a v1 version number
     print(f'Setting version number to {version}')
@@ -317,6 +335,7 @@ def main():
     conductor=args.conductor,
     is_v2_release=args.mode == V2_MODE,
     labels=['Update dependencies'] if args.mode == V1_MODE else [],
+    conflicted_files=conflicted_files
   )
 
 if __name__ == '__main__':