Bug 1274645: generate task labels for docker image builds; r=ahal

This monkey-patches the old taskcluster_graph code to avoid impacting branches
that are still using that support for decision graphs.  All of this will go
away when docker image builds become their own kind.

MozReview-Commit-ID: KukC3qqZDYA

--HG--
extra : rebase_source : 7bc4e89ad586120fdea78dfd7539633014ccc300
extra : source : 5e8b6de669628bf838432b93d1e1cff783b7ff62

taskcluster/taskgraph/kind/legacy.py

@@ -59,6 +59,10 @@ logger = logging.getLogger(__name__)
 def mklabel():
     return TASKID_PLACEHOLDER.format(slugid())
 
+# monkey-patch mklabel into image_builder, as well
+from taskcluster_graph import image_builder
+image_builder.mklabel = mklabel
+
 def set_expiration(task, timestamp):
     task_def = task['task']
     task_def['expires'] = timestamp

testing/taskcluster/taskcluster_graph/image_builder.py

@@ -22,6 +22,12 @@ DEFINE_TASK = 'queue:define-task:aws-provisioner-v1/{}'
 def is_docker_registry_image(registry_path):
     return os.path.isfile(registry_path)
 
+# make a task label; in old decision tasks, this is a regular slugid, but when called
+# from the taskgraph generator's legacy kind, this is monkey-patched to return a label
+# (`TaskLabel==..`)
+def mklabel():
+    return slugid()
+
 def docker_image(name):
     ''' Determine the docker tag/revision from an in tree docker file '''
     repository_path = os.path.join(DOCKER_ROOT, name, 'REGISTRY')
@@ -49,7 +55,7 @@ def task_id_for_image(seen_images, project, name, create=True):
     if not create:
         return None
 
-    task_id = slugid()
+    task_id = mklabel()
     seen_images[name] = {
         'taskId': task_id,
         'path': context_path,