Spring Boot集成Test Containers测试失败：UnknownHostException(app_db)

我基于Spring Boot + MySQL + Docker + Flyway实现了一个项目，使用Test Containers编写集成测试类时，程序始终尝试连接docker-compose中定义的app_db主机，抛出java.net.UnknownHostException: No such host is known (app_db)异常。以下是相关代码和配置：

测试类代码 #

@Testcontainers
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
public class UserControllerIntegrationTest {

    @Autowired
    private UserController userController;

    @Autowired
    UriComponentsBuilder builder;

    @Container
    public static MySQLContainer container = new MySQLContainer("mysql:latest")
            .withDatabaseName("example_db")
            .withUsername("Test")
            .withPassword("Test");

    @Container
    public static GenericContainer<?> redis =
            new GenericContainer<>(DockerImageName.parse("redis:6.2-alpine")).withExposedPorts(6379);

    @BeforeAll
    public static void setUp(){
        container.withReuse(true);
        container.withInitScript("src/main/test/resources/schema.sql");
        container.start();
        redis.start();
    }

    @DynamicPropertySource
    public static void overrideProperties(DynamicPropertyRegistry registry){
        registry.add("spring.datasource.url", container::getJdbcUrl);
        registry.add("spring.datasource.username", container::getUsername);
        registry.add("spring.datasource.password", container::getPassword);
        registry.add("spring.datasource.driver-class-name", container::getDriverClassName);
    }

    @Test
    public void testCreateUser(){
        CreateUserRequestDto request = new CreateUserRequestDto();
        request.setName("Test User");
        request.setAge(45);
        UserResponseDto response = userController.create(request);
        assertNotNull(response);
    }

}

docker-compose.yml配置 #

version: "3.0"
 services:
  api_service:
    build: .
    restart: always
    ports:
      - 8090:8090
    depends_on:
      - mysql_db
    links:
      - mysql_db:app_db
  mysql_db:
    image: "mysql:8.0"
    restart: always
    ports:
      - 3306:3306
    environment:
      MYSQL_DATABASE: test_db
      MYSQL_USER: user
      MYSQL_PASSWORD: password
      MYSQL_ROOT_PASSWORD: password

application.yml配置 #

app:
  name: test-service

server:
  port: 8090

spring:
  datasource:
    url: jdbc:mysql://app_db:3306/test_db
    username: user
    password: password
    initialization-mode: always
  jpa:
    properties:
      hibernate:
        dialect: org.hibernate.dialect.MySQL8Dialect
    hibernate:
      ddl-auto: create

报错信息 #

Caused by: java.net.UnknownHostException: No such host is known (app_db)

核心原因 #

测试代码中虽然通过@DynamicPropertySource尝试覆盖数据源配置，但因容器生命周期管理错误、配置加载顺序冲突，导致application.yml中app_db的原始配置未被正确覆盖，程序仍尝试连接docker-compose专属的内部主机名。

具体修复步骤 #

1. 修正TestContainers容器初始化逻辑 #

@Testcontainers注解会自动管理容器的启动/停止，手动调用start()会导致重复初始化，干扰动态属性注入：

• 删除@BeforeAll方法，移除手动启动容器的代码
• 将withReuse(true)和withInitScript直接放在容器实例化时配置，同时用classpath路径替代绝对路径，提高兼容性：

  @Container
  public static MySQLContainer container = new MySQLContainer("mysql:latest")
          .withDatabaseName("example_db")
          .withUsername("Test")
          .withPassword("Test")
          .withReuse(true)
          .withInitScript("classpath:schema.sql");
  
  @Container
  public static GenericContainer<?> redis =
          new GenericContainer<>(DockerImageName.parse("redis:6.2-alpine"))
                  .withExposedPorts(6379);
  

2. 补全动态属性覆盖（含Flyway） #

如果项目使用Flyway，它会独立读取数据源配置，需要一起覆盖：

@DynamicPropertySource
public static void overrideProperties(DynamicPropertyRegistry registry){
    registry.add("spring.datasource.url", container::getJdbcUrl);
    registry.add("spring.datasource.username", container::getUsername);
    registry.add("spring.datasource.password", container::getPassword);
    registry.add("spring.datasource.driver-class-name", container::getDriverClassName);
    // 覆盖Flyway配置（如果使用了Flyway）
    registry.add("spring.flyway.url", container::getJdbcUrl);
    registry.add("spring.flyway.user", container::getUsername);
    registry.add("spring.flyway.password", container::getPassword);
    // 覆盖Redis配置（如果需要使用Redis）
    registry.add("spring.redis.host", redis::getHost);
    registry.add("spring.redis.port", redis::getFirstMappedPort);
}

3. 为测试环境单独配置 #

创建src/test/resources/application-test.yml，隔离测试与生产配置：

spring:
  datasource:
    initialization-mode: never # 禁用默认初始化，改用TestContainers的initScript
  jpa:
    hibernate:
      ddl-auto: none # 避免与Flyway的Schema管理冲突
  flyway:
    enabled: true # 按需开启

然后在测试类上添加@ActiveProfiles("test")，指定使用测试配置：

@Testcontainers
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.NONE)
@ActiveProfiles("test") // 添加该注解
public class UserControllerIntegrationTest {
    // ... 其他代码
}

4. 验证Docker运行状态 #

确保本地Docker daemon处于运行状态，TestContainers能正常创建和管理容器。

内容的提问来源于stack exchange，提问作者Lakshitha Gihan