Docker Compose部署Spring Boot应用连接MySQL容器失败求助

问题描述 #

将开发的API打包为Docker镜像，尝试通过Docker Compose部署包含数据库在内的服务，但始终遭遇连接失败错误。调整数据库URL后，本地运行的API可成功连接容器化MySQL，但使用Docker Compose同时启动应用容器与MySQL容器时，应用无法连接数据库。

现有配置文件 #

docker-compose.yml #

version: "2.4"
services:
  trivia-quiz:
    image: omotoso/trivia-quiz-api
    ports:
      - "8080:8080"
    environment:
      SPRING_PROFILES_ACTIVE: PROD
    depends_on:
      - mysql

  mysql:
    image: mysql
    ports:
      - "3000:3306" 
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: db
      MYSQL_USER: my_user
      MYSQL_PASSWORD: password
    volumes:
      - mysql-data:/var/lib/mysql
  
volumes:
  mysql-data:

app.yaml（Spring Boot配置） #

spring:
  datasource:
    driver-class-name: com.mysql.cj.jdbc.Driver
    password: password
    url: jdbc:mysql://localhost:3000/db
    username: my_user
  jpa:
    hibernate:
      ddl-auto: update
    show-sql: false

错误信息 #

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
        at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-j-8.3.0.jar!/:8.3.0]
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-j-8.3.0.jar!/:8.3.0]
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:815) ~[mysql-connector-j-8.3.0.jar!/:8.3.0]
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:438) ~[mysql-connector-j-8.3.0.jar!/:8.3.0]
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241) ~[mysql-connector-j-8.3.0.jar!/:8.3.0]
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:189) ~[mysql-connector-j-8.3.0.jar!/:8.3.0]
        at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-5.0.1.jar!/:na]
        at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:359) ~[HikariCP-5.0.1.jar!/:na]
        at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:201) ~[HikariCP-5.0.1.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:470) ~[HikariCP-5.0.1.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:561) ~[HikariCP-5.0.1.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:100) ~[HikariCP-5.0.1.jar!/:na]
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) ~[HikariCP-5.0.1.jar!/:na]

解决方案 #

1. 修正数据库连接URL #

Docker Compose默认会为服务创建内部网络，容器之间需通过服务名互相访问，而非localhost；同时容器内MySQL使用默认端口3306，不是映射到主机的3000。

修改app.yaml中的数据库URL：

spring:
  datasource:
    url: jdbc:mysql://mysql:3306/db?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC

• mysql是docker-compose中MySQL服务的名称，内部网络可直接解析
• 添加useSSL=false、allowPublicKeyRetrieval=true适配MySQL 8.x默认安全配置
• serverTimezone=UTC避免时区不匹配导致的连接错误

2. 确保数据库就绪后再启动应用 #

depends_on仅保证启动顺序，不确保MySQL服务完全就绪。添加健康检查，让应用等待数据库可用后再启动：

更新docker-compose.yml：

version: "2.4"
services:
  trivia-quiz:
    image: omotoso/trivia-quiz-api
    ports:
      - "8080:8080"
    environment:
      SPRING_PROFILES_ACTIVE: PROD
    depends_on:
      mysql:
        condition: service_healthy  # 等待MySQL健康检查通过

  mysql:
    image: mysql
    ports:
      - "3000:3306" 
    environment:
      MYSQL_ROOT_PASSWORD: password
      MYSQL_DATABASE: db
      MYSQL_USER: my_user
      MYSQL_PASSWORD: password
    volumes:
      - mysql-data:/var/lib/mysql
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-h", "localhost", "-u", "root", "-ppassword"]
      interval: 5s  # 每5秒检查一次
      timeout: 5s   # 超时时间5秒
      retries: 5    # 重试5次后标记为不健康
  
volumes:
  mysql-data:

3. 用环境变量灵活覆盖配置（推荐） #

避免硬编码配置，通过Docker环境变量覆盖Spring Boot参数，无需修改镜像内的配置文件：

更新docker-compose.yml的trivia-quiz服务：

trivia-quiz:
  image: omotoso/trivia-quiz-api
  ports:
    - "8080:8080"
  environment:
    SPRING_PROFILES_ACTIVE: PROD
    SPRING_DATASOURCE_URL: jdbc:mysql://mysql:3306/db?useSSL=false&allowPublicKeyRetrieval=true&serverTimezone=UTC
    SPRING_DATASOURCE_USERNAME: my_user
    SPRING_DATASOURCE_PASSWORD: password
  depends_on:
    mysql:
      condition: service_healthy

此方式配置更灵活，适配不同部署环境，无需修改镜像内的配置文件。

内容的提问来源于stack exchange，提问作者Omotoso Iyanu