Spring Boot应用无法连接Google Cloud SQL(MySQL)求助

报错堆栈 #

com.zaxxer.hikari.pool.HikariPool$PoolInitializationException: Failed to initialize pool: Could not create connection to database server.
 at com.zaxxer.hikari.pool.HikariPool.throwPoolInitializationException(HikariPool.java:596)
 at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:582)
[省略部分堆栈]
 ... 74 more
Caused by: java.lang.RuntimeException: Unable to obtain credentials to communicate with the Cloud SQL API
 at com.google.cloud.sql.core.CoreSocketFactory$ApplicationDefaultCredentialFactory.create(CoreSocketFactory.java:392)
[省略部分堆栈]
 ... 83 more
Caused by: java.io.IOException: The Application Default Credentials are not available. They are available if running in Google Compute Engine. Otherwise, the environment variable GOOGLE_APPLICATION_CREDENTIALS must be defined pointing to a file defining the credentials.
 at com.google.auth.oauth2.DefaultCredentialsProvider.getDefaultCredentials(DefaultCredentialsProvider.java:125)
 at com.google.auth.oauth2.GoogleCredentials.getApplicationDefault(GoogleCredentials.java:125)
[省略部分堆栈]
 ... 91 more

依赖配置 #

<dependency>
    <groupId>com.google.cloud</groupId>
    <artifactId>spring-cloud-gcp-dependencies</artifactId>
    <version>3.3.0</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>

<dependency>
    <groupId>com.zaxxer</groupId>
    <artifactId>HikariCP</artifactId>
    <version>5.0.1</version>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>8.0.31</version>
    <scope>runtime</scope>
</dependency>

<dependency>
    <groupId>com.google.cloud.sql</groupId>
    <artifactId>mysql-socket-factory</artifactId>
    <version>1.11.0</version>
</dependency>

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-openfeign-core</artifactId>
    <version>4.0.1</version>
</dependency>

配置类 #

@Configuration
public class DatabaseConfig {

    @Bean
    public static DataSource dataSource() {
        HikariConfig config = new HikariConfig();
        config.setJdbcUrl(String.format("jdbc:mysql://google/%s", <database-name>));
        config.setUsername(<username>);
        config.setPassword(<password>);
        config.setMaximumPoolSize(5);
        config.addDataSourceProperty("socketFactory", "com.google.cloud.sql.mysql.SocketFactory");
        config.addDataSourceProperty("cloudSqlInstance", "<project-id>:<location>:<instance-name>");

        return new HikariDataSource(config);
    }
}

已做排查 #

• 检查配置：保留Google Cloud指南中的基础配置，疑问<database-name>是否与控制台数据库名、Cloud Shell中USE命令的名称一致
• 数据库设置：确认数据库可用，用户名密码可正常执行SQL，已开启公网访问和sqladmin API
• 尝试调整依赖，无明显效果
• 代码层面：通过DataSource创建JdbcTemplate调用queryForObject，判断代码逻辑无问题

问题解决与优化建议 #

1. 关于<database-name>的确认 #

是的，<database-name>就是Cloud SQL控制台中数据库列表里的名称，和你在Cloud Shell执行USE <database-name>时的名称完全一致，这部分你的理解是对的。

2. 核心问题：Application Default Credentials缺失 #

报错的根源是本地运行时没有提供Google Cloud的访问凭证，解决方法如下：

• 方法一：设置环境变量（推荐）
  1. 在Cloud Console的IAM -> 服务账号页面，找到对应服务账号（或新建一个具有Cloud SQL Client权限的服务账号）
  2. 创建并下载JSON格式的密钥文件
  3. 设置环境变量GOOGLE_APPLICATION_CREDENTIALS指向该文件路径：
     • Windows：set GOOGLE_APPLICATION_CREDENTIALS=C:\your-path\key-file.json
     • Linux/Mac：export GOOGLE_APPLICATION_CREDENTIALS=/your-path/key-file.json
• 方法二：在代码中指定凭证路径（仅测试用）
  在你的DatabaseConfig中添加一行配置：

  config.addDataSourceProperty("credentialsFile", "/your-path/key-file.json");
  

3. 依赖优化 #

你的依赖基本可用，但可以简化：

• 添加spring-cloud-gcp-starter-sql-mysql依赖，它会自动引入mysql-socket-factory等必要依赖，无需手动配置SocketFactory：

  <dependency>
      <groupId>com.google.cloud</groupId>
      <artifactId>spring-cloud-gcp-starter-sql-mysql</artifactId>
      <version>3.3.0</version>
  </dependency>
  

• 可以将mysql-connector-java替换为新的artifactIdmysql-connector-j（官方推荐，8.0.31版本支持）：

  <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-j</artifactId>
      <version>8.0.31</version>
      <scope>runtime</scope>
  </dependency>
  

4. 配置简化（替代自定义配置类） #

可以删除自定义的DatabaseConfig，改用application.properties配置：

spring.datasource.url=jdbc:mysql://google/<database-name>?cloudSqlInstance=<project-id>:<location>:<instance-name>&socketFactory=com.google.cloud.sql.mysql.SocketFactory
spring.datasource.username=<username>
spring.datasource.password=<password>
spring.datasource.hikari.maximum-pool-size=5
# 若需要指定凭证文件，添加以下配置
spring.cloud.gcp.sql.credentials.location=file:/your-path/key-file.json

内容的提问来源于stack exchange，提问作者Cheryl