Docker Compose中SpringBoot容器无法连接MySQL容器求助

问题场景 #

使用Docker Compose部署SpringBoot应用与MySQL 8.0容器，SpringBoot容器始终无法连接到MySQL。已尝试通过wait-for-it.sh脚本等待MySQL初始化完成、移除Docker Compose网络配置，均未解决问题。

提供的配置文件 #

Dockerfile #

FROM maven:3.8.1-openjdk-11 AS build

WORKDIR /app

COPY pom.xml .
COPY src ./src

RUN mvn clean package -DskipTests

FROM openjdk:11-jre-slim

RUN apt-get update && apt-get install -y default-mysql-client && rm -rf /var/lib/apt/lists/*

WORKDIR /app

COPY wait-for-it.sh .

RUN chmod +x wait-for-it.sh

COPY --from=build /app/target/Spring-MyParcial-MVC-DataJPA-Yamid-Punto3-0.0.1-SNAPSHOT.jar .

CMD ["./wait-for-it.sh", "db:3306", "--", "java", "-jar", "Spring-MyParcial-MVC-DataJPA-Yamid-Punto3-0.0.1-SNAPSHOT.jar"]

docker-compose.yml #

services:
  app:
    build: .
    ports:
      - "8080:8080"
    depends_on:
      db:
        condition: service_healthy
    environment:
      SPRING_DATASOURCE_URL: jdbc:mysql://db:3306/test
      SPRING_DATASOURCE_USERNAME: qwerty
      SPRING_DATASOURCE_PASSWORD: qwerty
      SPRING_JPA_HIBERNATE_DDL_AUTO: update
    networks:
      - app-network

  db:
    image: mysql:8.0
    environment:
      MYSQL_DATABASE: test
      MYSQL_ROOT_PASSWORD: qwerty
      MYSQL_USER: qwerty
      MYSQL_PASSWORD: qwerty
    ports:
      - "3306:3306"
    networks:
      - app-network
    healthcheck:
      test: ["CMD", "mysqladmin", "ping", "-h", "localhost"]
      interval: 10s
      timeout: 10s
      retries: 10

networks:
  app-network:
    driver: bridge

application.properties #

# Database connection settings
spring.datasource.url=jdbc:mysql://db:3306/test
spring.datasource.username=qwerty
spring.datasource.password=qwerty
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

wait-for-it.sh #

#!/bin/bash
# wait-for-it.sh

host="$1"
shift
cmd="$@"

until mysqladmin ping -h "$host" --silent; do
  >&2 echo "MySQL is unavailable - sleeping"
  sleep 1
done

>&2 echo "MySQL is up - executing command"
exec $cmd

日志信息 #

MySQL容器日志（springboot-db-1） #

2024-06-02 18:23:02 2024-06-02T23:23:02.745554Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Socket: /var/run/mysqld/mysqlx.sock
2024-06-02 18:23:02 2024-06-02T23:23:02.745716Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.37'  socket: '/var/run/mysqld/mysqld.sock'  port: 0  MySQL Community Server - GPL.
2024-06-02 18:23:03 Warning: Unable to load '/usr/share/zoneinfo/iso3166.tab' as time zone. Skipping it.
2024-06-02 18:23:03 Warning: Unable to load '/usr/share/zoneinfo/leap-seconds.list' as time zone. Skipping it.
2024-06-02 18:23:03 Warning: Unable to load '/usr/share/zoneinfo/leapseconds' as time zone. Skipping it.
2024-06-02 18:23:05 Warning: Unable to load '/usr/share/zoneinfo/tzdata.zi' as time zone. Skipping it.
2024-06-02 18:23:05 Warning: Unable to load '/usr/share/zoneinfo/zone.tab' as time zone. Skipping it.
2024-06-02 18:23:05 Warning: Unable to load '/usr/share/zoneinfo/zone1970.tab' as time zone. Skipping it.
2024-06-02 18:23:06 2024-06-02T23:23:06.050472Z 13 [System] [MY-013172] [Server] Received SHUTDOWN from user root. Shutting down mysqld (Version: 8.0.37).
2024-06-02 18:23:08 2024-06-02T23:23:08.086402Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.37)  MySQL Community Server - GPL.
2024-06-02 18:23:09 2024-06-02T23:23:09.284886Z 0 [Warning] [MY-011068] [Server] The syntax '--skip-host-cache' is deprecated and will be removed in a future release. Please use SET GLOBAL host_cache_size=0 instead.
2024-06-02 18:23:09 2024-06-02T23:23:09.286715Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.37) starting as process 1
2024-06-02 18:23:09 2024-06-02T23:23:09.294392Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2024-06-02 18:23:09 2024-06-02T23:23:09.474764Z 1 [System] [MY-013577] [InnoDB] InnoDB initialization has ended.
2024-06-02 18:23:09 2024-06-02T23:23:09.769065Z 0 [Warning] [MY-010068] [Server] CA certificate ca.pem is self signed.
2024-06-02 18:23:09 2024-06-02T23:23:09.769133Z 0 [System] [MY-013602] [Server] Channel mysql_main configured to support TLS. Encrypted connections are now supported for this channel.
2024-06-02 18:23:09 2024-06-02T23:23:09.778336Z 0 [Warning] [MY-011810] [Server] Insecure configuration for --pid-file: Location '/var/run/mysqld' in the path is accessible to all OS users. Consider choosing a different directory.
2024-06-02 18:23:09 2024-06-02T23:23:09.810279Z 0 [System] [MY-011323] [Server] X Plugin ready for connections. Bind-address: '::' port: 33060, socket: /var/run/mysqld/mysqlx.sock
2024-06-02 18:23:09 2024-06-02T23:23:09.810419Z 0 [System] [MY-010931] [Server] /usr/sbin/mysqld: ready for connections. Version: '8.0.37'  socket: '/var/run/mysqld/mysqld.sock'  port: 3306  MySQL Community Server - GPL.

SpringBoot容器日志（springboot-app-1） #

2024-06-02 18:24:11 MySQL is unavailable - sleeping
2024-06-02 18:24:12 MySQL is unavailable - sleeping
2024-06-02 18:24:13 MySQL is unavailable - sleeping
2024-06-02 18:24:14 MySQL is unavailable - sleeping

问题分析 #

从日志可见，MySQL容器已正常启动并监听3306端口，但SpringBoot容器的wait-for-it.sh脚本一直无法ping通MySQL，核心问题有两点：

1. 调用脚本时传入参数db:3306，脚本直接将整串作为主机名传给mysqladmin ping -h，但mysqladmin的-h仅接收主机名，端口需用-P单独指定，导致连接目标错误。
2. mysqladmin ping默认使用当前系统用户发起请求，容器内无对应MySQL用户，需显式指定配置的用户名密码才能成功 ping 通。

解决方案 #

方案1：修改wait-for-it.sh脚本，支持拆分主机和端口 #

更新后的脚本：

#!/bin/bash
# wait-for-it.sh

# 拆分传入的主机和端口参数
IFS=':' read -r host port <<< "$1"
# 默认端口设为3306
port=${port:-3306}
shift
cmd="$@"

# 显式指定MySQL用户名和密码执行ping操作
until mysqladmin ping -h "$host" -P "$port" -u qwerty -pqwerty --silent; do
  >&2 echo "MySQL is unavailable - sleeping"
  sleep 1
done

>&2 echo "MySQL is up - executing command"
exec $cmd

方案2：修改Dockerfile的CMD命令，简化参数传递 #

修改Dockerfile中的CMD行：

CMD ["./wait-for-it.sh", "db", "--", "java", "-jar", "Spring-MyParcial-MVC-DataJPA-Yamid-Punto3-0.0.1-SNAPSHOT.jar"]

同时更新wait-for-it.sh：

#!/bin/bash
# wait-for-it.sh

host="$1"
port="3306"
shift
cmd="$@"

until mysqladmin ping -h "$host" -P "$port" -u qwerty -pqwerty --silent; do
  >&2 echo "MySQL is unavailable - sleeping"
  sleep 1
done

>&2 echo "MySQL is up - executing command"
exec $cmd

额外兼容优化（可选） #

若修改后SpringBoot仍无法连接，可能是MySQL 8.0默认的caching_sha2_password认证插件与驱动不兼容，可在docker-compose.yml的db服务中添加环境变量：

environment:
  # 保留原有变量...
  MYSQL_DEFAULT_AUTH: mysql_native_password

验证步骤 #

1. 停止并删除现有容器：docker-compose down
2. 重新构建镜像：docker-compose build
3. 启动服务：docker-compose up
4. 查看SpringBoot容器日志，确认不再循环打印“MySQL is unavailable”，应用正常启动即可。

内容的提问来源于stack exchange，提问作者sappho7124