Use autoconfig.php provided by the image

.examples/docker-compose/with-nginx-proxy/mariadb/apache/docker-compose.yml

@@ -13,7 +13,7 @@ services:
       - db.env
 
   app:  
-    build: ./app
+    image: nextcloud:apache
     restart: always
     volumes:
       - nextcloud:/var/www/html
@@ -21,6 +21,8 @@ services:
       - VIRTUAL_HOST=
       - LETSENCRYPT_HOST=
       - LETSENCRYPT_EMAIL=
+    environment:
+      - MYSQL_HOST=db
     env_file:
       - db.env
     depends_on: