Bug 1370421 - Verify we don't write Perfherder data to same bucket; r=mshal

It is really easy to copy and paste taskgraph or mozharness configs
and cause Perfherder data to be written to the same bucket, resulting
in non-useful metrics collection.

This commit adds a taskgraph transform for the "build" kind that
attempts to look for multiple build jobs writing to the same
Perfherder bucket.

It isn't perfect. But it has already flushed out some jobs writing
to the same bucket and therefore producing bimodal Perfherder data.

MozReview-Commit-ID: COyvXwMiM32

--HG--
extra : rebase_source : 05dd227ceddcd4822e5689217873ec76912e7d30

taskcluster/ci/build/kind.yml

@@ -7,6 +7,7 @@ loader: taskgraph.loader.transform:loader
 transforms:
    - taskgraph.transforms.build:transforms
    - taskgraph.transforms.build_attrs:transforms
+   - taskgraph.transforms.build_lints:transforms
    - taskgraph.transforms.job:transforms
    - taskgraph.transforms.task:transforms
 

taskcluster/taskgraph/transforms/build_lints.py

@@ -0,0 +1,58 @@
+# 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/.
+"""
+Apply some defaults and minor modifications to the jobs defined in the build
+kind.
+"""
+
+from __future__ import absolute_import, print_function, unicode_literals
+
+from taskgraph.transforms.base import TransformSequence
+
+transforms = TransformSequence()
+
+
+@transforms.add
+def check_mozharness_perfherder_options(config, jobs):
+    """Verify that multiple jobs don't use the same perfherder bucket.
+
+    Build jobs record perfherder metrics by default. Perfherder metrics go
+    to a bucket derived by the platform by default. The name can further be
+    customized by the presence of "extra options" either defined in
+    mozharness sub-configs or in an environment variable.
+
+    This linter tries to verify that no 2 jobs will send Perfherder metrics
+    to the same bucket by looking for jobs not defining extra options when
+    their platform or mozharness config are otherwise similar.
+    """
+    seen_configs = {}
+
+    for job in jobs:
+        if job['run']['using'] != 'mozharness':
+            yield job
+            continue
+
+        worker = job.get('worker', {})
+
+        platform = job['treeherder']['platform']
+        primary_config = job['run']['config'][0]
+        options = worker.get('env', {}).get('PERFHERDER_EXTRA_OPTIONS')
+        nightly = job.get('attributes', {}).get('nightly', False)
+
+        # This isn't strictly necessary. But the Perfherder code looking at the
+        # values we care about is only active on builds. So it doesn't make
+        # sense to run this linter elsewhere.
+        assert primary_config.startswith('builds/')
+
+        key = (platform, primary_config, nightly, options)
+
+        if key in seen_configs:
+            raise Exception('Non-unique Perfherder data collection for jobs '
+                            '%s and %s: set PERFHERDER_EXTRA_OPTIONS in worker '
+                            'environment variables or use different mozconfigs'
+                            % (job['name'], seen_configs[key]['name']))
+
+        seen_configs[key] = job
+
+        yield job