backport-pr.py

#!/usr/bin/env python
from __future__ import print_function
from github import Github, GithubException
from sys import exit
from os.path import expanduser
from argparse import ArgumentParser
from cms_static import GH_CMSSW_ORGANIZATION
from cms_static import GH_CMSSW_REPO
from _py2with3compatibility import run_cmd
CMSSW_GIT_REF="/cvmfs/cms.cern.ch/cmssw.git.daily"

def backport_pull (repo, pr, branch):
  pr_branch = pr.base.label.split(":")[1]
  print("Source Branch:",pr_branch)
  if pr_branch == branch: return "Warning: Can not backport, same branch %s vs %s" % (pr_branch, branch),False
  br = gh_repo.get_branch(branch)
  commits = []
  for c in pr.get_commits().reversed: commits.insert(0,"git cherry-pick %s" % c.sha)
  if not commits: return "There are no commits to backport",False
  print("Cherry-pick commands:")
  print("  "+"\n  ".join(commits))
  if len(commits)>=250:
    return "Error: Too many commits in PR %s\nBot can only handle max 250 commits." % len(commits),False
  new_branch = "backport-%s-%s" % (branch.replace("/","_"), pr.number)
  print("New Branch:",new_branch)
  git_ref = ""
  if repo.name == "cmssw": git_ref = "--reference "+CMSSW_GIT_REF
  print("GIT REF:",git_ref)
  e , o = run_cmd("rm -rf pr_backport; git clone --branch %s %s git@github.com:%s pr_backport && cd pr_backport && git checkout -b %s" % (branch, git_ref, repo.full_name, new_branch))
  if e:
    print(o)
    exit(1)
  e, o = run_cmd('cd pr_backport; %s' % ";".join(commits))
  if e: return "Error: Failed to cherry-pick commits. Please backport this PR yourself.\n```"+o+"\n```",False
  e, o = run_cmd("cd pr_backport; git push origin %s" % new_branch)
  if e:
    print(o)
    exit(1)
  run_cmd("rm -rf pr_backport")
  newBody = "backport of #%s\n\n%s" %(pr.number, pr.body)
  newPR = repo.create_pull(title = pr.title, body = newBody, base = branch, head = new_branch )
  return "Successfully backported PR #%s as #%s for branch %s" % (pr.number, newPR.number, branch),True

if __name__ == "__main__":
  parser = ArgumentParser()
  parser.add_argument("-r", "--repository", dest="repository", help="Github Repositoy name e.g. cmssw.", type=str, default=GH_CMSSW_REPO)
  parser.add_argument("-b", "--branch",     dest="branch",     help="Repository branch for which new Pull request should be created.", type=str, default=None)
  parser.add_argument("-p", "--pull", dest="pull", help="Pull request number to be backported.", type=int, default=0)
  args = parser.parse_args()

  if args.pull == 0: parser.error("Missing pull request number.")
  if not args.branch: parser.error("Missing branch name.")

  gh = Github(login_or_token=open(expanduser("~/.github-token")).read().strip())
  gh_repo = gh.get_repo(GH_CMSSW_ORGANIZATION+"/"+args.repository)
  pr = gh_repo.get_pull(args.pull)
  res = backport_pull (gh_repo, pr, args.branch)
  status = "done"
  if not res[1]: status = "failed\n**Reason:**\n"
  print(res)
  pr.create_issue_comment("backport %s\n%s" % (status, res[0]))