Add persistent volumes, tweak database host

compose.yml

@@ -6,19 +6,18 @@ services:
     environment:
       # see https://ghost.org/docs/config/#configuration-options
       database__client: mysql
-      database__connection__host: db
+      database__connection__host: ${STACK_NAME}_db
       database__connection__user: root
       database__connection__password: ghost
       database__connection__database: ghost
-      # this url value is just an example, and is likely wrong for your environment!
       url: https://$DOMAIN
       # contrary to the default mentioned in the linked documentation, this image defaults to NODE_ENV=production (so development mode needs to be explicitly specified if desired)
       #NODE_ENV: development
-    volumes:
-      - "ghost_content:/var/lib/ghost/content"
     networks:
       - proxy
       - backend
+    volumes:
+      - "ghost_content:/var/lib/ghost/content/"
     deploy:
       restart_policy:
         condition: on-failure
@@ -45,6 +44,8 @@ services:
       - backend
     environment:
       MYSQL_ROOT_PASSWORD: ghost
+    volumes:
+      - "mysql:/var/lib/mysql"
 
 networks:
   proxy:
@@ -52,4 +53,5 @@ networks:
   backend:
 
 volumes:
+  mysql:
   ghost_content: