【Azure 应用服务】App Service 无法连接到Azure MySQL服务，报错-CFANZ编程社区

问题描述

App Service使用jdbc连接MySQL服务，出现大量的 Communications link failure：

com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from

问题分析

最开始出现连接不上的原因，怀疑是MySQL服务的IP地址白名单没有配置正确的App Service 出站IP。但是根据错误提示，发现明显不对，因为如果是IP地址不允许访问，它的错误消息应该是：

Client with IP address '183.2xx.xx.xx' is not allowed to connect to this

所以不应该是MySQL服务器对IP白名单设置的问题。

为了深入找出问题，单独用Java Spring Boot来写一个简单的数据库连接代码，根据MySQL官方的代码：https://docs.azure.cn/zh-cn/mysql/connect-java

POM.XML内容为：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>

    <properties>
        <java.version>1.8</java.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>

    <dependencies>
8.0.20</version>
        </dependency>

注：这里使用的 mysql-connector-java 依赖版本为 8.0.20

Java Main函数代码：

public static void main(String[] args) {
        String url = "jdbc:mysql://xxxxxx.mysql.database.chinacloudapi.cn:3306/xxxxxx?useSSL=true&requireSSL=false&characterEncoding=utf8&serverTimezone=UTC";
        String username = "xxxxxx@xxxxxx";
        String password = "xxxxxxxxxxxx";
        try {
            Connection connection = DriverManager.getConnection(url, username, password);
            System.out.println(connection.getMetaData().getURL());
            connection.close();
            System.out.println("connected!");
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            System.out.println(e.getMessage());
            return; // return because nothing can be done w/out a connection
        }

    }

同样的数据库连接字符串，运行结果正常。根据验证结果对比，出现 Communications link failure | The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server，的JDBC版本为 8.0.15，所以瞬间定位问题原因：客户端jdbc的驱动问题。

根据这一判断，再次检查了MySQL的版本为8.0并且为单实例(Single Server)。而微软的官方文档中提示了 use 8.0.17+ with MySQL 8.0 (https://docs.microsoft.com/en-us/azure/mysql/concepts-compatibility#mysql-drivers)

【Azure 应用服务】App Service 无法连接到Azure MySQL服务，报错_App Service