Before:
```
version: "2"

services:
  master:
    image: erkules/galera:basic
    container_name: master
    volumes:
      - /data:/var/lib/mysql
    networks:
      - mysql
    command: --wsrep-cluster-name=local-test --wsrep-cluster-address=gcomm://

  slave:
    depends_on:
      - master
    image: erkules/galera:basic
    networks:
      - mysql
    command: --wsrep-cluster-name=local-test --wsrep-cluster-address=gcomm://master

  wordpress:
    depends_on:
      - slave
    image: wordpress
    networks:
      - mysql
      - proxy
    environment:
      - WORDPRESS_DB_HOST=slave:3306
      - WORDPRESS_DB_USER=wordpress
      - WORDPRESS_DB_PASSWORD=PASSWORD
    ports:
      - "80:80"

networks:
  mysql:
  proxy:
```
After:
```
version: "2"

services:
  master:
    image: erkules/galera:basic
    container_name: master
    volumes:
      - /data:/var/lib/mysql
    networks:
      - mysql
    command: --wsrep-cluster-name=local-test --wsrep-cluster-address=gcomm://

  slave:
    depends_on:
      - master
    image: erkules/galera:basic
    networks:
      - mysql
    command: --wsrep-cluster-name=local-test --wsrep-cluster-address=gcomm://master

  wordpress:
    depends_on:
      - slave
    image: wordpress
    networks:
      - mysql
      - proxy
    environment:
      - WORDPRESS_DB_HOST=slave:3306
      - WORDPRESS_DB_USER=wordpress
      - WORDPRESS_DB_PASSWORD=PASSWORD

  webproxy:
    depends_on:
      - wordpress
    build: webproxy
    networks:
      - proxy
    ports:
      - "80:80"

networks:
  mysql:
  proxy:
```
請確認 webproxy 目錄中的 proxy.conf 的設定連接埠是否正確。