use NestedDeserializableDataclass for config

service.py

@@ -1,16 +1,13 @@
 #!/usr/bin/env python3
 import asyncio
 import datetime
-import json
 import logging
 import signal
 
-import aiofiles
-
 from alerting import alerts
-from alerting.common import CONFIG_FILE
 from misc import checks, cvars
 from misc.checkers import interval_checker, scheduled_checker
+from misc.config import get_config
 
 logging.basicConfig(level=logging.INFO)
 
@@ -25,9 +22,7 @@ def stop_gracefully(signum, frame):
 async def main():
     signal.signal(signal.SIGTERM, stop_gracefully)
 
-    async with aiofiles.open(CONFIG_FILE) as f:
-        contents = await f.read()
-    cvars.config.set(json.loads(contents))
+    cvars.config.set(get_config())
 
     client = await alerts.get_client()
     cvars.matrix_client.set(client)