Ballerina服务运行报错排查：代码问题还是服务器问题？

之前运行正常的Ballerina代码近期突然报错，无法确定是代码问题还是Ballerina服务端问题，请求排查。

相关代码 #

import ballerinax/mysql;
import ballerinax/mysql.driver as _;
import ballerina/http;
import ballerina/log;
import ballerina/sql;

configurable int port = ?;
configurable string database = ?;
configurable string password = ?;
configurable string user = ?;
configurable string host = ?;

type output record {
  boolean valid;
  boolean isGuilty?;
  string charges?;
};

type Person record {
  string nic;
  @sql:Column {name: "isguilty"}
  int isGuilty;
  string charges?;
};

mysql:Client mysqlEp = check new (host = host, user = user, password = password, database =database, port = port);

# A service representing a network-accessible API
# bound to port `9090`.
service / on new http:Listener(9090) {

   //function for checking the police records by nic
   resource function get policeCheck/[string nic]() returns output|error? {
       Person|error queryRowResponse=mysqlEp->queryRow(`select * from police_details where nic=${nic.trim()}`);

       if queryRowResponse is error{
          output result={
              valid: false
          };
          log:printInfo("Invalid NIC");
          return result;
      }else{
          Person person=queryRowResponse;
          if person.isGuilty==0{
              output result={
                  valid: true,
                  isGuilty: false
              };
              log:printInfo(result.toBalString());
              return result;
          }else if person.isGuilty==1 {
              output result={
                  valid: true,
                  isGuilty: true,
                  charges:<string>person.charges
              };
              log:printInfo(result.toBalString());
              return result;
          }

    
      }
      return;
  }
}

报错信息 #

• 核心错误：mysql:Error occurred in MySQL client connector: Connection refused (Connection refused)
• 关联异常：java.sql.SQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.

排查结论与验证步骤 #

1. 排除代码问题：代码逻辑未改动且此前运行正常，MySQL客户端初始化、SQL查询写法均符合规范，无语法或逻辑错误，因此报错和代码本身无关。

2. 问题定位：报错本质是MySQL连接失败，属于数据库网络/配置层面问题，和Ballerina服务端无关，大概率是以下场景：

   • MySQL服务未启动，或监听端口被修改
   • 配置项变更：host/port/user/password/database任一参数配置错误
   • 网络限制：Ballerina运行环境无法访问MySQL服务器的对应端口（防火墙/安全组拦截）
   • MySQL用户权限变更：配置的用户无远程连接权限，或密码过期
   • MySQL服务异常：数据库崩溃、连接数耗尽

3. 验证步骤：

   • 用MySQL客户端（命令行/Navicat等）使用相同配置参数连接数据库，确认能否成功
   • 检查MySQL服务状态，确认服务正常运行
   • 核对配置文件中的数据库参数是否准确
   • 检查防火墙/安全组规则，确保Ballerina所在机器可访问MySQL端口
   • 查看MySQL日志，获取连接失败的详细记录

内容的提问来源于stack exchange，提问作者Muthahhar97