Mininet交换机无法连控制器及SpringBoot-Docker无法连MySQL求助

问题1：Mininet环境中交换机无法连接控制器 #

排查与解决步骤 #

• 确认控制器已正常启动，且监听端口（默认OpenFlow端口为6633/6653）处于开放状态
• 启动Mininet时显式指定控制器地址，执行命令：

  mn --controller=remote,ip=控制器IP地址,port=监听端口
  

• 检查防火墙规则，确保Mininet主机与控制器之间的端口通信未被拦截
• 通过ping命令验证控制器与Mininet主机的网络可达性
• 查看Mininet控制台日志和控制器日志，定位具体连接失败的错误信息

问题2：Docker部署的SpringBoot应用无法连接MySQL（未使用Docker Compose） #

执行docker build -t springbootmysql .构建镜像后，启动应用出现连接失败错误，错误日志如下：

2023-01-06 00:42:24 2023-01-05 16:42:24.864  INFO 1 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2023-01-06 00:42:24 2023-01-05 16:42:24.867  WARN 1 --- [           main] com.zaxxer.hikari.util.DriverDataSource  : Registered driver with driverClassName=com.mysql.jdbc.Driver was not found, trying direct instantiation.
2023-01-06 00:42:25 2023-01-05 16:42:25.935 ERROR 1 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Exception during pool initialization.
2023-01-06 00:42:25 
2023-01-06 00:42:25 com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure
2023-01-06 00:42:25 
2023-01-06 00:42:25 The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
2023-01-06 00:42:25     at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-j-8.0.31.jar!/:8.0.31]
2023-01-06 00:42:24 Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
2023-01-06 00:42:25     at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-j-8.0.31.jar!/:8.0.31]
2023-01-06 00:42:25     at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:828) ~[mysql-connector-j-8.0.31.jar!/:8.0.31]
2023-01-06 00:42:25     at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:448) ~[mysql-connector-j-8.0.31.jar!/:8.0.31]
2023-01-06 00:42:25     at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:241) ~[mysql-connector-j-8.0.31.jar!/:8.0.31]
2023-01-06 00:42:25     at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-j-8.0.31.jar!/:8.0.31]
2023-01-06 00:42:25     at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-4.0.3.jar!/:na]
2023-01-06 00:42:25     at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:364) ~[HikariCP-4.0.3.jar!/:na]
202

当前application.properties配置：

spring.datasource.url=jdbc:mysql://mysqldb:3306/spring_boot_todo
spring.datasource.username=root
spring.datasource.password=xxxx
spring.datasource.driverClassName=com.mysql.jdbc.Driver
spring.jpa.hibernate.ddl-auto=create

MySQL已存在目标数据库，数据库列表：

+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| spring_boot_todo   |
| sys                |
+--------------------+

Docker容器名称见截图。

针对性解决步骤 #

1. 修正数据库驱动配置
   日志提示com.mysql.jdbc.Driver已过时，替换为新版驱动并优化配置：

   spring.datasource.url=jdbc:mysql://mysqldb:3306/spring_boot_todo?useSSL=false&serverTimezone=UTC
   spring.datasource.username=root
   spring.datasource.password=xxxx
   # 新版驱动可通过SPI自动注册，无需手动指定driverClassName
   # spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
   spring.jpa.hibernate.ddl-auto=create
   

2. 确保Docker容器处于同一网络
   若SpringBoot与MySQL容器不在同一网络，需创建并加入自定义网络：

   # 创建应用专属网络
   docker network create app-network
   # 重启MySQL容器并加入网络（替换为实际MySQL容器名）
   docker stop mysqldb
   docker run -d --name mysqldb --network app-network -p 3306:3306 -e MYSQL_ROOT_PASSWORD=xxxx mysql:latest
   # 启动SpringBoot容器时加入同一网络
   docker run -d --name springbootmysql --network app-network -p 8080:8080 springbootmysql
   

3. 授权MySQL远程连接权限
   MySQL 8.0默认限制远程连接，需进入容器配置权限：

   # 进入MySQL容器终端
   docker exec -it mysqldb mysql -uroot -pxxxx
   # 执行授权命令
   ALTER USER 'root'@'%' IDENTIFIED WITH mysql_native_password BY 'xxxx';
   FLUSH PRIVILEGES;
   

4. 验证数据库URL主机名
   若容器不在同一网络，需将URL中的mysqldb替换为宿主机器IP（如172.17.0.1或宿主实际公网/内网IP）：

   spring.datasource.url=jdbc:mysql://宿主IP:3306/spring_boot_todo?useSSL=false&serverTimezone=UTC
   

5. 重新构建并启动容器
   修改配置后重新构建镜像：

   docker build -t springbootmysql .
   

   再按上述网络配置启动容器即可。

内容的提问来源于stack exchange，提问作者masa