Bug 1414919 - [taskgraph] Allow morph templates to also modify task attributes, r=dustin

The motivation for this change is to create a 'rebuild' template that sets
'attributes.task_duplicates'. A nice side effect is that if any of 'task'
or 'attributes' aren't explicitly set, we can ignore the result which means
we don't need to have a whole bunch of 'else' clauses in the templates.

MozReview-Commit-ID: DX3UyFGb4ff

--HG--
extra : rebase_source : b768cb9f9df3cb22827209519f1cd2a4944af74f

taskcluster/docs/try.rst

@@ -106,32 +106,23 @@ be applied to every task no matter what. If the template should only be applied
 to certain kinds of tasks, this needs to be specified in the template itself
 using JSON-e `condition statements`_.
 
-The context available to the JSON-e render aims to match that of ``actions``.
-It looks like this:
+The context available to the JSON-e render contains attributes from the
+:py:class:`taskgraph.task.Task` class. It looks like this:
 
 .. parsed-literal::
 
     {
-      "task": {
-        "payload": {
-          "env": { ... },
-          ...
-        }
-        "extra": {
-          "treeherder": { ... },
-          ...
-        },
-        "tags": { "kind": "<kind>", ... },
-        ...
-      },
-      "input": {
-        "enabled": 1,
-        ...
-      },
-      "taskId": "<task id>"
+      "attributes": task.attributes,
+      "kind": task.kind,
+      "task": task.task,
+      "taskId": task.task_id,
+      "input": ...
     }
 
-See the `existing templates`_ for examples.
+The ``input`` context can be any arbitrary value or object. What it contains
+depends on each specific template. Templates must return objects that have have
+either ``attributes`` or ``task`` as a top level key. All other top level keys
+will be ignored. See the `existing templates`_ for examples.
 
 Empty Try
 :::::::::

taskcluster/moz.build

@@ -27,3 +27,4 @@ PYTHON_UNITTEST_MANIFESTS += [
     'taskgraph/test/python.ini',
 ]
 SPHINX_TREES['taskcluster'] = 'docs'
+SPHINX_PYTHON_PACKAGE_DIRS += ['taskgraph']

taskcluster/taskgraph/morph.py

@@ -268,12 +268,17 @@ class apply_jsone_templates(object):
                     'taskId': task.task_id,
                     'kind': task.kind,
                     'input': self.templates[template],
+                    # The following context differs from action tasks
+                    'attributes': task.attributes,
                 }
 
                 template_path = os.path.join(self.template_dir, template + '.yml')
                 with open(template_path) as f:
                     template = yaml.load(f)
-                task.task = jsone.render(template, context)
+                result = jsone.render(template, context) or {}
+                for attr in ('task', 'attributes'):
+                    if attr in result:
+                        setattr(task, attr, result[attr])
 
         return taskgraph, label_to_taskid
 

taskcluster/taskgraph/templates/artifact.yml

@@ -3,16 +3,13 @@ $if: task["tags"]
 then:
     $if: task.tags["kind"] == "build"
     then:
-        $mergeDeep:
-            - $eval: task
-            - extra:
-                  treeherder:
-                      symbol: Ba
-            - payload:
-                  env:
-                      USE_ARTIFACT:
-                          $eval: input.enabled
-    else:
-        $eval: task
-else:
-    $eval: task
+        task:
+            $mergeDeep:
+                - $eval: task
+                - extra:
+                      treeherder:
+                          symbol: Ba
+                - payload:
+                      env:
+                          USE_ARTIFACT:
+                              $eval: input.enabled

taskcluster/taskgraph/templates/env.yml

@@ -1,5 +1,6 @@
-$mergeDeep:
-    - $eval: task
-    - payload:
-          env:
-              $eval: input
+task:
+    $mergeDeep:
+        - $eval: task
+        - payload:
+              env:
+                  $eval: input