swarming: send task tags to event_mon

appengine/swarming/event_mon_metrics.py

Index: appengine/swarming/event_mon_metrics.py
diff --git a/appengine/swarming/event_mon_metrics.py b/appengine/swarming/event_mon_metrics.py
index a0d1437f8cee09b650f582a9b3f51b99a74c0b8d..4af025fd702c8a99f3fbf562c00bf830dbe40df4 100644
--- a/appengine/swarming/event_mon_metrics.py
+++ b/appengine/swarming/event_mon_metrics.py
@@ -25,6 +25,20 @@ DIMENSIONS = (
 )
 
 
+TAGS = {
+    'build_id': ['buildnumber'],
+    'buildername': ['buildername'],
+    'codereview': ['rietveld'],
+    'master': ['master'],
+    'name': ['name'],
+    'patch_project': ['patch_project'],
+    'project': ['project'],
+    'purpose': ['purpose'],
+    'slavename': ['slavename'],
+    'stepname': ['stepname'],
+}
+
+
 def _to_timestamp(dt):
   return int(time.mktime(dt.timetuple()))
 
@@ -140,6 +154,15 @@ def _task_summary_to_proto(summary, event):
     event.proto.swarming_task_event.deduped_from = summary.deduped_from
   event.proto.swarming_task_event.try_number = summary.try_number
 
+  for tag in summary.tags:
+    if ':' not in tag:
+      logging.error('Unexpected tag: %r', tag)
+      continue
+    name, value = tag.split(':', 1)
+    for event_tag, task_tags in TAGS.iteritems():
+      if name in task_tags:
+        getattr(event.proto.swarming_task_event.tags, event_tag).append(value)
+
 
 def initialize():
   gae_event_mon.initialize('swarming')