Add persisted db volume

docker-compose.yml

@@ -35,6 +35,8 @@ services:
       start_period: 5s
     networks:
       - database
+    volumes:
+      - pg_data:/var/lib/postgresql/data
   grafana:
     image: grafana/grafana:latest
     labels:
@@ -59,3 +61,5 @@ networks:
     driver: bridge
   redis:
     driver: bridge
+volumes:
+  pg_data: {}