大家好，又见面了，我是你们的朋友全栈君。

问题

今天开了一台新的阿里云服务器，启动Docker容器内的Spring boot程序，数据库(阿里云的)一直死活连不上去。

2020-12-01 14:39:56.178  INFO [svc-activity,,,] 8 --- [           main] com.zaxxer.hikari.HikariDataSource       : HikariPool-1 - Starting...
2020-12-01 14:49:57.493 ERROR [svc-activity,,,] 8 --- [           main] com.zaxxer.hikari.pool.HikariPool        : HikariPool-1 - Exception during pool initialization.


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.
        at com.mysql.cj.jdbc.exceptions.SQLError.createCommunicationsException(SQLError.java:174) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:64) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:836) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:456) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:246) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.zaxxer.hikari.util.DriverDataSource.getConnection(DriverDataSource.java:138) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.PoolBase.newConnection(PoolBase.java:358) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.PoolBase.newPoolEntry(PoolBase.java:206) ~[HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.createPoolEntry(HikariPool.java:477) [HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.checkFailFast(HikariPool.java:560) [HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.pool.HikariPool.<init>(HikariPool.java:115) [HikariCP-3.4.5.jar!/:na]
        at com.zaxxer.hikari.HikariDataSource.getConnection(HikariDataSource.java:112) [HikariCP-3.4.5.jar!/:na]
        at org.springframework.jdbc.datasource.DataSourceUtils.fetchConnection(DataSourceUtils.java:158) [spring-jdbc-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:116) [spring-jdbc-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:79) [spring-jdbc-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:324) [spring-jdbc-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.boot.jdbc.EmbeddedDatabaseConnection.isEmbedded(EmbeddedDatabaseConnection.java:120) [spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateDefaultDdlAutoProvider.getDefaultDdlAuto(HibernateDefaultDdlAutoProvider.java:42) [spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration.lambda$getVendorProperties$1(HibernateJpaConfiguration.java:130) [spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateSettings.getDdlAuto(HibernateSettings.java:41) ~[spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties.determineDdlAuto(HibernateProperties.java:136) ~[spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties.getAdditionalProperties(HibernateProperties.java:102) ~[spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties.determineHibernateProperties(HibernateProperties.java:94) ~[spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaConfiguration.getVendorProperties(HibernateJpaConfiguration.java:132) [spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.entityManagerFactory(JpaBaseConfiguration.java:133) ~[spring-boot-autoconfigure-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_222]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_222]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_222]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_222]
        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:650) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:635) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1336) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1176) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:556) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:516) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:324) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:322) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1109) ~[spring-context-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869) ~[spring-context-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.8.RELEASE.jar!/:5.2.8.RELEASE]
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.3.2.RELEASE.jar!/:2.3.2.RELEASE]
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_222]
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_222]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_222]
        at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_222]
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:49) ~[app.jar:na]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:109) ~[app.jar:na]
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:58) ~[app.jar:na]
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:88) ~[app.jar:na]
Caused by: com.mysql.cj.exceptions.CJCommunicationsException: 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.
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) ~[na:1.8.0_222]
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) ~[na:1.8.0_222]
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) ~[na:1.8.0_222]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:423) ~[na:1.8.0_222]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:61) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:105) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.exceptions.ExceptionFactory.createException(ExceptionFactory.java:151) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.exceptions.ExceptionFactory.createCommunicationsException(ExceptionFactory.java:167) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:544) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeProtocol.readServerCapabilities(NativeProtocol.java:496) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeProtocol.beforeHandshake(NativeProtocol.java:383) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeProtocol.connect(NativeProtocol.java:1346) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.NativeSession.connect(NativeSession.java:157) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:956) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:826) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        ... 57 common frames omitted
Caused by: java.net.SocketTimeoutException: Read timed out
        at java.net.SocketInputStream.socketRead0(Native Method) ~[na:1.8.0_222]
        at java.net.SocketInputStream.socketRead(SocketInputStream.java:116) ~[na:1.8.0_222]
        at java.net.SocketInputStream.read(SocketInputStream.java:171) ~[na:1.8.0_222]
        at java.net.SocketInputStream.read(SocketInputStream.java:141) ~[na:1.8.0_222]
        at com.mysql.cj.protocol.ReadAheadInputStream.fill(ReadAheadInputStream.java:107) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.ReadAheadInputStream.readFromUnderlyingStreamIfNecessary(ReadAheadInputStream.java:150) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.ReadAheadInputStream.read(ReadAheadInputStream.java:180) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at java.io.FilterInputStream.read(FilterInputStream.java:133) ~[na:1.8.0_222]
        at com.mysql.cj.protocol.FullReadInputStream.readFully(FullReadInputStream.java:64) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:63) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.SimplePacketReader.readHeader(SimplePacketReader.java:45) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        at com.mysql.cj.protocol.a.NativeProtocol.readMessage(NativeProtocol.java:538) ~[mysql-connector-java-8.0.22.jar!/:8.0.22]
        ... 63 common frames omitted

解决方案

这个的意思就是连接超时了，解决方向在连通性上，不要搞错方向了。
解决思路就是
1.检查数据库的连通性：
不要用ping，最直接的方法就是用mysql的连接工具在服务器上连一遍，如果成功就说明可以通。连不通注意检查阿里云的配置，一个是ECS的网络配置。另外一个是阿里云MySQL数据库白名单（我就是这个问题，能ping通了，连不上）

2.检查代码的数据库配置
这一项的配置，因为我不是这里出的问题，所以也找了一下这块的资料。
检查useSSL=false，driver-class-name的用com.mysql.cj.jdbc.Driver（connect的依赖要升到8），还有就是账号密码。(没试过，可能有误)