Terminate worker tasks on SIGINT

Fixes conda-incubator#707.

conda-store-server/conda_store_server/worker/tasks.py

@@ -1,10 +1,11 @@
 import datetime
 import os
 import shutil
+import sys
 import typing
 
 import yaml
-from celery import Task, shared_task
+from celery import Task, platforms, shared_task
 from celery.execute import send_task
 from celery.signals import worker_ready
 from conda_store_server import api, environment, schema, utils
@@ -44,6 +45,17 @@ def worker(self):
 
             self._worker.initialize()
 
+        # Installs a signal handler that terminates the process on Ctrl-C
+        # (SIGINT)
+        # Note: the following would not be enough to terminate beat and other
+        # tasks, which is why the code below explicitly calls sys.exit
+        # > from celery.apps.worker import install_worker_term_hard_handler
+        # > install_worker_term_hard_handler(self._worker, sig='SIGINT')
+        def _shutdown(*args, **kwargs):
+            return sys.exit(1)
+
+        platforms.signals["INT"] = _shutdown
+
         return self._worker