連線不到redis錯誤：

Caused by: io.netty.channel.ConnectTimeoutException: connection timed out: /192.168.211.133:6379

• 這個問題有很大的可能是Linux的防火牆未關閉，請求無法到達redis客戶端。

• 我使用的Centos7 ，檢視防火牆和6的命令應該是不同的，之前在這個地方都跌倒過了

2020-08-21 17:43:42.091  INFO 25692 --- [nio-8004-exec-4] io.lettuce.core.KqueueProvider           : Starting without optional kqueue library
org.springframework.data.redis.connection.PoolException: Could not get a resource from the pool; nested exception is io.lettuce.core.RedisConnectionException: Unable to connect to 
 
192.168.211.133:6379
    at org.springframework.data.redis.connection.lettuce.LettucePoolingConnectionProvider.getConnection(LettucePoolingConnectionProvider.java:109)
    at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory$SharedConnection.getNativeConnection(LettuceConnectionFactory.java:
 
1198)
    at org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory$SharedConnection.getConnection(LettuceConnectionFactory.java:1179)
　　　。
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    at java.lang.Thread.run(Thread.java:748)
Caused by: io.lettuce.core.RedisConnectionException: Unable to connect to 
 
192.168.211.133:6379
    at io.lettuce.core.RedisConnectionException.create(RedisConnectionException.java:78)
    at io.lettuce.core.RedisConnectionException.create(RedisConnectionException.java:56)
    at io.lettuce.core.AbstractRedisClient.getConnection(AbstractRedisClient.java:234)
    at io.lettuce.core.RedisClient.connect(RedisClient.java:207)
    at org.springframework.data.redis.connection.lettuce.StandaloneConnectionProvider.lambda$getConnection$1(StandaloneConnectionProvider.java:115)
    at java.util.Optional.orElseGet(Optional.java:267)
    at org.springframework.data.redis.connection.lettuce.StandaloneConnectionProvider.getConnection(StandaloneConnectionProvider.java:115)
    at org.springframework.data.redis.connection.lettuce.LettucePoolingConnectionProvider.lambda$null$0(LettucePoolingConnectionProvider.java:97)
    at io.lettuce.core.support.ConnectionPoolSupport$RedisPooledObjectFactory.create(ConnectionPoolSupport.java:209)
    at io.lettuce.core.support.ConnectionPoolSupport$RedisPooledObjectFactory.create(ConnectionPoolSupport.java:199)
    at org.apache.commons.pool2.BasePooledObjectFactory.makeObject(BasePooledObjectFactory.java:58)
    at org.apache.commons.pool2.impl.GenericObjectPool.create(GenericObjectPool.java:889)
    at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:424)
    at org.apache.commons.pool2.impl.GenericObjectPool.borrowObject(GenericObjectPool.java:349)
    at io.lettuce.core.support.ConnectionPoolSupport$1.borrowObject(ConnectionPoolSupport.java:122)
    at io.lettuce.core.support.ConnectionPoolSupport$1.borrowObject(ConnectionPoolSupport.java:117)
    at org.springframework.data.redis.connection.lettuce.LettucePoolingConnectionProvider.getConnection(LettucePoolingConnectionProvider.java:103)
    ... 69 more
Caused by: io.netty.channel.ConnectTimeoutException: connection timed out: /192.168.211.133:6379
    at io.netty.channel.nio.AbstractNioChannel$AbstractNioUnsafe$1.run(AbstractNioChannel.java:261)
    at io.netty.util.concurrent.PromiseTask.runTask(PromiseTask.java:98)
    at io.netty.util.concurrent.ScheduledFutureTask.run(ScheduledFutureTask.java:150)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:510)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:518)
    at io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1050)
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
    ... 1 more

• 外部訪問redis的前提是把redis配置檔案中的 protected-mode yes,改為 protected-mode no 這樣redis才允許外部訪問

• 檢視Linux防火牆狀態命令：systemctl status firewalld.service

systemctl status firewalld.service

• running 是防火牆正在執行

原來是防火牆沒有關閉

• 關閉防火強命令：systemctl stop firewalld.service
• 出現 dead 說明防火強關閉

systemctl stop firewalld.service

成功了

在redis中可以檢視到快取資料【不知道為什麼開始沒查到，又刷了幾次頁面查到了】