Optionally use the GH API to open PRs from the cherrypick_pr script (e…

…lastic#3627)

If you add the `--create_pr` parameter, and have a GH token in
`~/.github_token`, the script will also create a PR for you, with the right
title and tags already set.

dev-tools/cherrypick_pr

@@ -1,17 +1,20 @@
 #!/usr/bin/env python
 import sys
+import json
 import argparse
+from os.path import expanduser
 from subprocess import check_call, call, check_output
+import requests
 
 """
 Example usage:
 
-./dev-tools/cherrypick_pr 5.0 2565 6490604aa0cf7fa61932a90700e6ca988fc8a527
+./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 5.0 2565 6490604aa0cf7fa61932a90700e6ca988fc8a527 --continue
+./dev-tools/cherrypick_pr --create_pr 5.0 2565 6490604aa0cf7fa61932a90700e6ca988fc8a527 --continue
 
 This script does the following:
 
@@ -20,8 +23,9 @@ This script does the following:
 * calls the git cherry-pick command in this branch
 * after fixing the merge errors (if needed), pushes the branch to your
   remote
-
-You then just need to go to Github and open the PR.
+* 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 in the
+  `~/.github_token` file.
 
 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
@@ -45,6 +49,9 @@ def main():
                         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 ~/.github_token)")
     args = parser.parse_args()
 
     print args
@@ -91,9 +98,39 @@ def main():
          shell=True)
     check_call("git push --set-upstream {} {}"
                .format(remote, tmp_branch), shell=True)
-    print("Done. Open PR by following this URL: \n\t" +
-          "https://github.com/elastic/beats/compare/{}...{}:{}?expand=1"
-          .format(args.to_branch, remote, tmp_branch))
+    if not args.create_pr:
+        print("Done. Open PR by following this URL: \n\t" +
+              "https://github.com/elastic/beats/compare/{}...{}:{}?expand=1"
+              .format(args.to_branch, remote, tmp_branch))
+    else:
+        token = open(expanduser("~/.github_token"), "r").read().strip()
+        base = "https://api.github.com/repos/elastic/beats"
+        s = requests.Session()
+        s.headers.update({"Authorization": "token " + token})
+
+        original_pr = s.get(base+"/pulls/"+args.pr_number).json()
+
+        # create PR
+        r = s.post(base+"/pulls", json=dict(
+            title="Cherry-pick to {}: {}"
+                  .format(args.to_branch, original_pr["title"]),
+            head=remote + ":" + 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 r.status_code > 299:
+            print("Creating PR failed: {}".format(r.json()))
+            sys.exit(1)
+        new_pr = r.json()
+
+        # add labels
+        s.post(base+"/issues/{}/labels".format(new_pr["number"]),
+               json=["backport", "review"])
+
+        print("\nDone. PR created: {}".format(new_pr["html_url"]))
+        print("Please go and check it and add the review tags")
+
 
 if __name__ == "__main__":
     sys.exit(main())