Add cherrypick_pr dev-tools helper.

(cherry picked from commit 50affd5)

dev-tools/cherrypick_pr

@@ -0,0 +1,209 @@
+#!/usr/bin/env python3
+"""Cherry pick and backport a PR"""
+from __future__ import print_function
+
+from builtins import input
+import sys
+import os
+import argparse
+from os.path import expanduser
+import re
+from subprocess import check_call, call, check_output
+import requests
+
+usage = """
+Example usage:
+
+./dev-tools/cherrypick_pr --create_pr 5.0 2565 6490604aa0cf7fa61932a90700e6ca988fc8a527
+
+In case of backporting errors, fix them, then run:
+
+git cherry-pick --continue
+./dev-tools/cherrypick_pr --create_pr 5.0 2565 6490604aa0cf7fa61932a90700e6ca988fc8a527 --continue
+
+This script does the following:
+
+* cleanups both from_branch and to_branch (warning: drops local changes)
+* creates a temporary branch named something like "branch_2565"
+* calls the git cherry-pick command in this branch
+* after fixing the merge errors (if needed), pushes the branch to your
+  remote
+* if the --create_pr flag is used, it uses the GitHub API to create the PR
+  for you. Note that this requires you to have a Github token with the
+  public_repo scope in the `~/.elastic/github.token` file. This token
+  should be also authorized to Elastic organization so as to work with single-sign-on.
+  (see https://help.github.com/en/articles/authorizing-a-personal-access-token-for-use-with-saml-single-sign-on)
+
+Note that you need to take the commit hashes from `git log` on the
+from_branch, copying the IDs from Github doesn't work in case we squashed the
+PR.
+"""
+
+
+def main():
+    """Main"""
+    parser = argparse.ArgumentParser(
+        description="Creates a PR for cherry-picking commits",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog=usage)
+    parser.add_argument("to_branch",
+                        help="To branch (e.g 7.x)")
+    parser.add_argument("pr_number",
+                        help="The PR number being merged (e.g. 2345)")
+    parser.add_argument("commit_hashes", metavar="hash", nargs="+",
+                        help="The commit hashes to cherry pick." +
+                        " You can specify multiple.")
+    parser.add_argument("--yes", action="store_true",
+                        help="Assume yes. Warning: discards local changes.")
+    parser.add_argument("--continue", action="store_true",
+                        help="Continue after fixing merging errors.")
+    parser.add_argument("--from_branch", default="master",
+                        help="From branch")
+    parser.add_argument("--create_pr", action="store_true",
+                        help="Create a PR using the Github API " +
+                        "(requires token in ~/.elastic/github.token)")
+    parser.add_argument("--diff", action="store_true",
+                        help="Display the diff before pushing the PR")
+    parser.add_argument("--remote", default="",
+                        help="Which remote to push the backport branch to")
+    parser.add_argument("--zube-team", default="",
+                        help="Team the PR belongs to")
+    parser.add_argument("--keep-backport-label", action="store_true",
+                        help="Preserve label needs_backport in original PR")
+    args = parser.parse_args()
+
+    print(args)
+
+    tmp_branch = "backport_{}_{}".format(args.pr_number, args.to_branch)
+
+    if not vars(args)["continue"]:
+        if not args.yes and input("This will destroy all local changes. " +
+                                      "Continue? [y/n]: ") != "y":
+            return 1
+        check_call("git reset --hard", shell=True)
+        check_call("git clean -df", shell=True)
+        check_call("git fetch", shell=True)
+
+        check_call("git checkout {}".format(args.from_branch), shell=True)
+        check_call("git pull", shell=True)
+
+        check_call("git checkout {}".format(args.to_branch), shell=True)
+        check_call("git pull", shell=True)
+
+        call("git branch -D {} > /dev/null".format(tmp_branch), shell=True)
+        check_call("git checkout -b {}".format(tmp_branch), shell=True)
+        if call("git cherry-pick -x {}".format(" ".join(args.commit_hashes)),
+                shell=True) != 0:
+            print("Looks like you have cherry-pick errors.")
+            print("Fix them, then run: ")
+            print("    git cherry-pick --continue")
+            print("    {} --continue".format(" ".join(sys.argv)))
+            return 1
+
+    if len(check_output("git status -s", shell=True).strip()) > 0:
+        print("Looks like you have uncommitted changes." +
+              " Please execute first: git cherry-pick --continue")
+        return 1
+
+    if len(check_output("git log HEAD...{}".format(args.to_branch),
+                        shell=True).strip()) == 0:
+        print("No commit to push")
+        return 1
+
+    if args.diff:
+        call("git diff {}".format(args.to_branch), shell=True)
+        if input("Continue? [y/n]: ") != "y":
+            print("Aborting cherry-pick.")
+            return 1
+
+    print("Ready to push branch.")
+
+    remote = args.remote
+    if not remote:
+        remote = input("To which remote should I push? (your fork): ")
+
+    call("git push {} :{} > /dev/null".format(remote, tmp_branch),
+         shell=True)
+    check_call("git push --set-upstream {} {}"
+               .format(remote, tmp_branch), shell=True)
+    if not args.create_pr:
+        print("Done. Open PR by following this URL: \n\t" +
+              "https://github.com/elastic/fleet-server/compare/{}...{}:{}?expand=1"
+              .format(args.to_branch, remote, tmp_branch))
+    else:
+        token = open(expanduser("~/.elastic/github.token"), "r").read().strip()
+        base = "https://api.github.com/repos/elastic/fleet-server"
+        session = requests.Session()
+        session.headers.update({"Authorization": "token " + token})
+
+        original_pr = session.get(base + "/pulls/" + args.pr_number).json()
+
+        # get the github username from the remote where we pushed
+        remote_url = check_output("git remote get-url {}".format(remote),
+                                  shell=True)
+        remote_user = re.search("github.com[:/](.+)/fleet-server", str(remote_url)).group(1)
+
+        # create PR
+        request = session.post(base + "/pulls", json=dict(
+            title="Cherry-pick #{} to {}: {}".format(args.pr_number, args.to_branch, original_pr["title"]),
+            head=remote_user + ":" + tmp_branch,
+            base=args.to_branch,
+            body="Cherry-pick of PR #{} to {} branch. Original message: \n\n{}"
+            .format(args.pr_number, args.to_branch, original_pr["body"])
+        ))
+        if request.status_code > 299:
+            print("Creating PR failed: {}".format(request.json()))
+            sys.exit(1)
+        new_pr = request.json()
+
+        # add labels
+        labels = ["backport"]
+
+        zube_teams = zube_team_labels(original_pr)
+        if args.zube_team:
+            resp = session.get(base + "/labels/Team:"+args.zube_team)
+            if resp.status_code != 200:
+                print("Cannot find team label", resp.text)
+                sys.exit(1)
+            zube_teams = ["Team:" + args.zube_team]
+
+        if len(zube_teams) > 0:
+            labels += zube_teams
+            labels.append("[zube]: In Review")
+        else:
+            labels.append("review")
+
+        session.post(
+            base + "/issues/{}/labels".format(new_pr["number"]), json=labels)
+
+        if not args.keep_backport_label:
+            # remove needs backport label from the original PR
+            session.delete(base + "/issues/{}/labels/needs_backport".format(args.pr_number))
+
+        # get version and set a version label on the original PR
+        version = get_version(os.getcwd())
+        if version:
+            session.post(
+                base + "/issues/{}/labels".format(args.pr_number), json=["v" + version])
+
+        print("\nDone. PR created: {}".format(new_pr["html_url"]))
+        print("Please go and check it and add the review tags")
+
+def get_version(repo_dir):
+    pattern = re.compile(r'(const\s|)\w*(v|V)ersion\s=\s"(?P<version>.*)"')
+    with open(os.path.join(repo_dir, "main.go"), "r") as f:
+        for line in f:
+            match = pattern.match(line)
+            if match:
+                return match.group('version')
+
+def zube_team_labels(pr):
+    teams = []
+    for label in pr.get('labels', []):
+        name = label.get('name', '')
+        if name.startswith('Team:'):
+            teams.append(name)
+    return teams
+
+if __name__ == "__main__":
+    sys.exit(main())