diff --git a/app.py b/app.py
index 9ddc3d587..d87c4e89a 100644
--- a/app.py
+++ b/app.py
@@ -20,7 +20,7 @@ from data.billing import Billing
 from data.buildlogs import BuildLogs
 from data.archivedlogs import LogArchive
 from data.userevent import UserEventsBuilderModule
-from data.queue import WorkQueue
+from data.queue import WorkQueue, MetricQueueReporter
 from util.saas.analytics import Analytics
 from util.saas.exceptionlog import Sentry
 from util.names import urn_generator
@@ -137,7 +137,7 @@ oauth_apps = [github_login, github_trigger, gitlab_trigger, google_login]
 
 image_diff_queue = WorkQueue(app.config['DIFFS_QUEUE_NAME'], tf)
 dockerfile_build_queue = WorkQueue(app.config['DOCKERFILE_BUILD_QUEUE_NAME'], tf,
-                                   metric_queue=metric_queue)
+                                   reporter=MetricQueueReporter(metric_queue))
 notification_queue = WorkQueue(app.config['NOTIFICATION_QUEUE_NAME'], tf)
 
 database.configure(app.config)
diff --git a/data/queue.py b/data/queue.py
index 26cbce8ad..289b99ada 100644
--- a/data/queue.py
+++ b/data/queue.py
@@ -13,11 +13,22 @@ class NoopWith:
   def __exit__(self, type, value, traceback):
     pass
 
+class MetricQueueReporter(object):
+  def __init__(self, metric_queue):
+    self._metric_queue = metric_queue
+
+  def __call__(self, currently_processing, running_count, total_count):
+    need_capacity_count = total_count - running_count
+    self._metric_queue.put('BuildCapacityShortage', need_capacity_count, unit='Count')
+
+    building_percent = 100 if currently_processing else 0
+    self._metric_queue.put('PercentBuilding', building_percent, unit='Percent')
+
 class WorkQueue(object):
   def __init__(self, queue_name, transaction_factory,
-               canonical_name_match_list=None, metric_queue=None):
+               canonical_name_match_list=None, reporter=None):
     self._queue_name = queue_name
-    self._metric_queue = metric_queue
+    self._reporter = reporter
     self._transaction_factory = transaction_factory
     self._currently_processing = False
 
@@ -75,14 +86,12 @@ class WorkQueue(object):
     return (running_count, available_not_running_count, available_count)
 
   def update_metrics(self):
-    if self._metric_queue is None:
+    if self._reporter is None:
       return
 
     (running_count, available_not_running_count, available_count) = self.get_metrics()
-    self._metric_queue.put('BuildCapacityShortage', available_not_running_count, unit='Count')
-
-    building_percent = 100 if self._currently_processing else 0
-    self._metric_queue.put('PercentBuilding', building_percent, unit='Percent')
+    self._reporter(self._currently_processing, running_count,
+                   running_count + available_not_running_count)
 
   def has_retries_remaining(self, item_id):
     """ Returns whether the queue item with the given id has any retries remaining. If the