Adding extra logging to celery tasks ans gunicorn, specifically log on SIGTERM and SIGINIT so that we can track better when an app restarts and why it restarts e.g. when it restarts after another signal.

app/celery/statistics_tasks.py

@@ -1,3 +1,4 @@
+from celery.signals import worker_process_shutdown
 from sqlalchemy.exc import SQLAlchemyError
 
 from app import notify_celery
@@ -23,6 +24,11 @@ def create_outcome_notification_statistic_tasks(notification):
         record_outcome_job_statistics.apply_async((str(notification.id),), queue=QueueNames.STATISTICS)
 
 
+@worker_process_shutdown.connect
+def worker_process_shutdown(sender, signal, pid, exitcode):
+    current_app.logger.info('Statistics worker shutdown: PID: {} Exitcode: {}'.format(pid, exitcode))
+
+
 @notify_celery.task(bind=True, name='record_initial_job_statistics', max_retries=20, default_retry_delay=10)
 @statsd(namespace="tasks")
 def record_initial_job_statistics(self, notification_id):