Bug 1665414 - Allow for Docker images to be defined in comm/taskcluster/docker. r=mkmelin

Docker image context directories go under comm/taskcluster/docker and must be
defined in comm/taskcluster/ci/docker-image/docker-image.yml in order for
the decision task to find them properly.

Differential Revision: https://phabricator.services.mozilla.com/D92705

--HG--
extra : moz-landing-system : lando

taskcluster/comm_taskgraph/__init__.py

@@ -25,7 +25,8 @@ def register(graph_config):
     the process.
     """
     logger.info("{} path registered".format(__name__))
-    _import_modules(['documentation', 'actions', 'target_tasks', 'transforms.job.toolchain'])
+    _import_modules(['documentation', 'util.docker', 'actions', 'target_tasks',
+                     'transforms.job.toolchain'])
 
 
 def _import_modules(modules):

taskcluster/comm_taskgraph/util/docker.py

@@ -0,0 +1,27 @@
+# -*- coding: utf-8 -*-
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+import os
+import logging
+
+from .. import COMM
+from taskgraph.util import (
+    docker as utildocker,
+)
+
+logger = logging.getLogger(__name__)
+
+COMM_IMAGE_DIR = os.path.join(COMM, 'taskcluster', 'docker')
+
+
+def register():
+    logger.info("Registering comm docker image definition path.")
+    utildocker.image_paths.register('comm/taskcluster/ci/docker-image/docker-image.yml',
+                                    COMM_IMAGE_DIR)
+
+
+register()