Add a worker for reporting global stats to Prometheus

Fixes #1789

workers/globalpromstats.py

@@ -0,0 +1,56 @@
+import logging
+import time
+
+from app import app, metric_queue
+from data.database import UseThenDisconnect
+from data import model
+from util.locking import GlobalLock, LockNotAcquiredException
+from workers.worker import Worker
+
+logger = logging.getLogger(__name__)
+
+WORKER_FREQUENCY = app.config.get('GLOBAL_PROMETHEUS_STATS_FREQUENCY', 60 * 60)
+
+
+class GlobalPrometheusStatsWorker(Worker):
+  """ Worker which reports global stats (# of users, orgs, repos, etc) to Prometheus periodically.
+  """
+  def __init__(self):
+    super(GlobalPrometheusStatsWorker, self).__init__()
+    self.add_operation(self._try_report_stats, WORKER_FREQUENCY)
+
+  def _try_report_stats(self):
+    logger.debug('Attempting to report stats')
+
+    try:
+      with GlobalLock('GLOBAL_PROM_STATS'):
+        self._report_stats()
+    except LockNotAcquiredException:
+      return
+
+  def _report_stats(self):
+    logger.debug('Reporting global stats')
+    with UseThenDisconnect(app.config):
+      # Repository count.
+      metric_queue.repository_count.set(model.repository.get_repository_count())
+
+      # User counts.
+      metric_queue.user_count.set(model.user.get_active_user_count())
+      metric_queue.org_count.set(model.organization.get_active_org_count())
+      metric_queue.robot_count.set(model.user.get_robot_count())
+
+
+def main():
+  logging.config.fileConfig('conf/logging_debug.conf', disable_existing_loggers=False)
+
+  if not app.config.get('PROMETHEUS_AGGREGATOR_URL'):
+    logger.debug('Prometheus not enabled; skipping global stats reporting')
+    while True:
+      time.sleep(100000)
+
+  worker = GlobalPrometheusStatsWorker()
+  worker.start()
+
+
+if __name__ == "__main__":
+  main()