【Azure 应用服务】App Service 无法连接到Azure MySQL服务，报错：com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure

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 the server