ActiveMaster in AnnotationObserver

ActiveMaster in AnnotationObserver

To process @@@STEP_TRIGGER@@@ annotations and trigger builds using
buildbucket, AnnotationObserver needs ActiveMaster from master.config
because it references the service account credentials to use.

This change pulls active master from master.config through a bunch of
classes to AnnotationObserver. An upcoming change will use it.

R=stip@chromium.org
BUG=449218
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=294226

[nodir, 2015-02-25 21:11:34]

PTAL, a small CL

[ghost stip (do not use), 2015-02-25 22:11:14]

buildbot has a convoluted pointer setup for its objects, I feel like the factory
should be able to get info from activemaster already somehow

[nodir, 2015-02-25 22:23:27]

active master is not a buildbot concept and buildbot does not have a place to
store user-defined configuration values (I considered adding support for
user-defined global values, but thought this explicit approach will be simpler
and safer).

This master.cfg passes ActiveMaster only to AutoSetupMaster
https://chromium.googlesource.com/chromium/tools/build/+/master/masters/maste...

AutoSetupMaster passes it only to cbe_json_status_push.StatusPush which does not
put it to a global place
https://chromium.googlesource.com/chromium/tools/build/+/master/scripts/maste...

There is no global place where active master is stored

[ghost stip (do not use), 2015-02-25 22:38:29]

stip@chromium.org changed reviewers:
+ iannucci@chromium.org

[ghost stip (do not use), 2015-02-25 22:38:30]

hm, you're right. otherwise we could use self.build.builder.botmaster.

can I ask for an alternative approach? hardcode into the annotator observer the
filename to be the [directory of the master.cfg]/cred_locations.json.
That file has a builder -> credential mapping, with perhaps a 'default' mapping:

{
  "default": "cool_creds.creds"
  "builders": {
    "linux_chromium_rel": "cooler_linux_creds.creds"
  }
}

this file should be reloaded every time a connection is made to find the creds.
that way you don't specify additional configuration parameters to the factory,
and you can swap creds immediately without a master restart

[nodir, 2015-02-25 22:52:22]

the service account is per master, not builder. I am not sure there is a way to
get current master name because what we call master name is not a buildbot
concept, but a directory name in masters/

[ghost stip (do not use), 2015-02-25 22:54:53]

fair enough, lgtm

[nodir, 2015-02-25 22:55:41]

The CQ bit was checked by nodir@chromium.org

[commit-bot: I haz the power, 2015-02-25 22:58:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/955153003/1

[commit-bot: I haz the power, 2015-02-25 23:01:51]

Committed patchset #1 (id:1) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=294226