[users at bb.net] Gitlab, MRs, and try builds, oh my

[Dan Kegel]

On Mon, May 14, 2018 at 8:22 AM, Dan Kegel <dank at kegel.com> wrote:
> In days of yore, my old gitlab trybuild gateway read source_branch
> from the merge request,
> and used that to decide which branch to run the try build against.

To expand on that, the thinking is there are many ephemeral
merge request branches, so one can't go changing
master.cfg to know about all of them; that means merge request
builds really should be against the target branch.

If that is indeed correct, the fix seems trivial (passes tests, but
not tested in practice):

--- a/master/buildbot/test/unit/test_www_hooks_gitlab.py
+++ b/master/buildbot/test/unit/test_www_hooks_gitlab.py
@@ -222,7 +222,8 @@ class
TestChangeHookConfiguredWithGitChange(unittest.TestCase):
             calendar.timegm(change["when_timestamp"].utctimetuple()),
             1325626589
         )
-        self.assertEqual(change["branch"], "ms-viewport")
+        self.assertEqual(change["branch"], "master")
+        self.assertEqual(change['properties']["source_branch"], 'ms-viewport')
         self.assertEqual(change['properties']["target_branch"], 'master')
         self.assertEqual(change["category"], "merge_request")

diff --git a/master/buildbot/www/hooks/gitlab.py
b/master/buildbot/www/hooks/gitlab.py
index f2fc4383b..8d55bd92d 100644
--- a/master/buildbot/www/hooks/gitlab.py
+++ b/master/buildbot/www/hooks/gitlab.py
@@ -115,12 +115,13 @@ class GitLabHandler(BaseHookHandler):
             'comments': "MR#{}: {}\n\n{}".format(attrs['iid'],
attrs['title'], attrs['description']),
             'revision': commit['id'],
             'when_timestamp': when_timestamp,
-            'branch': attrs['source_branch'],
+            'branch': attrs['target_branch'],
             'repository': repo_url,
             'project': project,
             'category': event,
             'revlink': attrs['url'],
             'properties': {
+                'source_branch': attrs['source_branch'],
                 'target_branch': attrs['target_branch'],
                 'target_repository': attrs['target']['git_http_url'],
                 'event': event,

Is anyone depending on the existing behavior?

> There is one further wrinkle: my old buildbot instance used naming conventions
> to map project + branch to trybuilders

I'm hoping I can put that logic into master.cfg, but haven't checked yet.
- Dan