github · robertbrignull · Jun 12, 2020 · Jun 12, 2020
diff --git a/.github/update-release-branch.py b/.github/update-release-branch.py
@@ -0,0 +1,178 @@
+import datetime
+from github import Github
+import random
+import requests
+import subprocess
+import sys
+
+# The branch being merged from.
+# This is the one that contains day-to-day development work.
+MASTER_BRANCH = 'master'
+# The branch being merged into.
+# This is the release branch that users reference.
+LATEST_RELEASE_BRANCH = 'v1'
+# 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):
+  cmd = ['git', *args]
+  p = subprocess.run(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+  if (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')
+
+# Returns true if the given branch exists on the origin remote
+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 release branch
+def open_pr(repo, all_commits, short_master_sha, branch_name):
+  # Sort the commits into the pull requests that introduced them,
+  # and any commits that don't have a pull request
+  pull_requests = []
+  commits_without_pull_requests = []
+  for commit in all_commits:
+    pr = get_pr_for_commit(repo, commit)
+
+    if pr is None:
+      commits_without_pull_requests.append(commit)
+    elif not any(p for p in pull_requests if p.number == pr.number):
+      pull_requests.append(pr)
+
+  print('Found ' + str(len(pull_requests)) + ' pull requests')
+  print('Found ' + str(len(commits_without_pull_requests)) + ' commits not in a pull request')
+
+  # Sort PRs and commits by age
+  sorted(pull_requests, key=lambda pr: pr.number)
+  sorted(commits_without_pull_requests, key=lambda c: c.commit.author.date)
+
+  # Start constructing the body text
+  body = 'Merging ' + short_master_sha + ' into ' + LATEST_RELEASE_BRANCH
+
+  conductor = get_conductor(repo, pull_requests, commits_without_pull_requests)
+  body += '\n\nConductor for this PR is @' + conductor
+
+  # List all PRs merged
+  if len(pull_requests) > 0:
+    body += '\n\nContains the following pull requests:'
+    for pr in pull_requests:
+      merger = get_merger_of_pr(repo, pr)
+      body += '\n- #' + str(pr.number)
+      body += ' - ' + pr.title
+      body += ' (@' + merger + ')'
+
+  # List all commits not part of a PR
+  if len(commits_without_pull_requests) > 0:
+    body += '\n\nContains the following commits not from a pull request:'
+    for commit in commits_without_pull_requests:
+      body += '\n- ' + commit.sha
+      body += ' - ' + get_truncated_commit_message(commit)
+      body += ' (@' + commit.author.login + ')'
+
+  title = 'Merge ' + MASTER_BRANCH + ' into ' + LATEST_RELEASE_BRANCH
+
+  # Create the pull request
+  pr = repo.create_pull(title=title, body=body, head=branch_name, base=LATEST_RELEASE_BRANCH)
+  print('Created PR #' + str(pr.number))
+
+  # Assign the conductor
+  pr.add_to_assignees(conductor)
+  print('Assigned PR to ' + conductor)
+
+# Gets the person who should be in charge of the mergeback PR
+def get_conductor(repo, pull_requests, other_commits):
+  # If there are any PRs then use whoever merged the last one
+  if len(pull_requests) > 0:
+    return get_merger_of_pr(repo, pull_requests[-1])
+
+  # Otherwise take the author of the latest commit
+  return other_commits[-1].author.login
+
+# Gets a list of the SHAs of all commits that have happened on master
+# since the release branched off.
+# This will not include any commits that exist on the release branch
+# that aren't on master.
+def get_commit_difference(repo):
+  commits = run_git('log', '--pretty=format:%H', ORIGIN + '/' + LATEST_RELEASE_BRANCH + '...' + MASTER_BRANCH).strip().split('\n')
+
+  # Convert to full-fledged commit objects
+  commits = [repo.get_commit(c) for c in commits]
+
+  # Filter out merge commits for PRs
+  return list(filter(lambda c: not is_pr_merge_commit(c), commits))
+
+# Is the given commit the automatic merge commit from when merging a PR
+def is_pr_merge_commit(commit):
+  return commit.committer.login == 'web-flow' and len(commit.parents) > 1
+
+# Gets a copy of the commit message that should display nicely
+def get_truncated_commit_message(commit):
+  message = commit.commit.message.split('\n')[0]
+  if len(message) > 60:
+    return message[:57] + '...'
+  else:
+    return message
+
+# Converts a commit into the PR that introduced it to the master branch.
+# Returns the PR object, or None if no PR could be found.
+def get_pr_for_commit(repo, commit):
+  prs = commit.get_pulls()
+
+  if prs.totalCount > 0:
+    # In the case that there are multiple PRs, return the earliest one
+    prs = list(prs)
+    sorted(prs, key=lambda pr: int(pr.number))
+    return prs[0]
+  else:
+    return None
+
+# Get the person who merged the pull request.
+# For most cases this will be the same as the author, but for PRs opened
+# by external contributors getting the merger will get us the GitHub
+# employee who reviewed and merged the PR.
+def get_merger_of_pr(repo, pr):
+  return repo.get_commit(pr.merge_commit_sha).author.login
+
+def main():
+  if len(sys.argv) != 3:
+    raise Exception('Usage: update-release.branch.py <github token> <repository nwo>')
+  github_token = sys.argv[1]
+  repository_nwo = sys.argv[2]
+
+  repo = Github(github_token).get_repo(repository_nwo)
+
+  # Print what we intend to go
+  print('Considering difference between ' + MASTER_BRANCH + ' and ' + LATEST_RELEASE_BRANCH)
+  short_master_sha = run_git('rev-parse', '--short', MASTER_BRANCH).strip()
+  print('Current head of ' + MASTER_BRANCH + ' is ' + short_master_sha)
+
+  # See if there are any commits to merge in
+  commits = get_commit_difference(repo)
+  if len(commits) == 0:
+    print('No commits to merge from ' + MASTER_BRANCH + ' to ' + LATEST_RELEASE_BRANCH)
+    return
+
+  # The branch name is based off of the name of branch being merged into
+  # and the SHA of the branch being merged from. Thus if the branch already
+  # exists we can assume we don't need to recreate it.
+  new_branch_name = 'update-' + LATEST_RELEASE_BRANCH + '-' + short_master_sha
+  print('Branch name is ' + new_branch_name)
+
+  # Check if the branch already exists. If so we can abort as this script
+  # has already run on this combination of branches.
+  if branch_exists_on_remote(new_branch_name):
+    print('Branch ' + new_branch_name + ' already exists. Nothing to do.')
+    return
+
+  # Create the new branch and push it to the remote
+  print('Creating branch ' + new_branch_name)
+  run_git('checkout', '-b', new_branch_name, MASTER_BRANCH)
+  run_git('push', ORIGIN, new_branch_name)
+
+  # Open a PR to update the branch
+  open_pr(repo, commits, short_master_sha, new_branch_name)
+
+if __name__ == '__main__':
+  main()
diff --git a/.github/workflows/update-release-branch.yml b/.github/workflows/update-release-branch.yml
@@ -0,0 +1,28 @@
+name: Update release branch
+on:
+  schedule:
+    - cron: 0 9 * * 1
+  repository_dispatch:
+    types: [update-release-branch]
+
+jobs:
+  update:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+      with:
+        # Need full history so we calculate diffs
+        fetch-depth: 0
+
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: 3.5
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install PyGithub==1.51 requests
+
+    - name: Update release branch
+      run: python .github/update-release-branch.py ${{ secrets.GITHUB_TOKEN }} ${{ github.repository }}