Bug 1381597 - create a taskcluster task that tests the decision graph for invalid buildbot-bridge builder names. r=dustin

This adds a download of allthethings.json to the Decision Task (in optimize phase).

If there is a network error, in order to avoid a broken decision task, we treat all buildbot-bridge jobs as valid.

MozReview-Commit-ID: GpKVV5pUwGL

taskcluster/taskgraph/util/bbb_validation.py

@@ -0,0 +1,53 @@
+# -*- 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 json
+import logging
+import requests
+
+from mozbuild.util import memoize
+from redo import retry
+from requests import exceptions
+
+ALLTHETHINGS_URL = "https://secure.pub.build.mozilla.org/builddata/reports/allthethings.json.gz"
+
+logger = logging.getLogger(__name__)
+
+
+def fetch_all_the_things():
+    response = retry(requests.get, attempts=2, sleeptime=10,
+                     args=(ALLTHETHINGS_URL,),
+                     kwargs={'timeout': 60})
+    return response.content
+
+
+@memoize
+def valid_bbb_builders():
+    try:
+        allthethings = fetch_all_the_things()
+        builders = set(json.loads(allthethings).get('builders', {}).keys())
+        return builders
+
+    # In the event of request times out, requests will raise a TimeoutError.
+    except exceptions.Timeout:
+        logger.warning("Timeout fetching list of buildbot builders.")
+
+    # In the event of a network problem (e.g. DNS failure, refused connection, etc),
+    # requests will raise a ConnectionError.
+    except exceptions.ConnectionError:
+        logger.warning("Connection Error while fetching list of buildbot builders")
+
+    # We just print the error out as a debug message if we failed to catch the exception above
+    except exceptions.RequestException as error:
+        logger.warning(error)
+
+    # When we get invalid JSON (i.e. 500 error), it results in a ValueError
+    except ValueError as error:
+        logger.warning("Invalid JSON, possible server error: {}".format(error))
+
+    # None returned to treat as "All Builders Valid"
+    return None