深刻理解Redis集群（下）：Redis 哨兵（Sentinel）模式

背景

现在对3个节点的sentinel进行配置。sentinel的配置文件在redis的安装目录中已经存在，只需要复制到指定的位置即可。

sentinel是独立进程，有对应的脚本来执行。

基于之前的redis 一主二从的架构，我们继续启动3个sentinel进程。

哨兵模式的架构图如下：

启动哨兵们

• sentinel6379.conf

protected-mode no
port 26379


daemonize yes
pidfile "/var/run/redis-sentinel_26379.pid"
logfile "/usr/local/redis-6.2.14/logs/redis-sentinel_26379.log"
dir "/private/tmp"


sentinel monitor mymaster 127.0.0.1 6379 2


sentinel announce-hostnames no
# Generated by CONFIG REWRITE
user default on nopass ~* &* +@all
sentinel myid c384816840b671b2f194ebd417458c6bbd08230c
sentinel config-epoch mymaster 0
sentinel leader-epoch mymaster 0
sentinel current-epoch 0
sentinel known-replica mymaster 127.0.0.1 6381
sentinel known-replica mymaster 127.0.0.1 6380
sentinel known-sentinel mymaster 127.0.0.1 26381 789f7ad2247aa6104665ced751c1956e87ec175b
sentinel known-sentinel mymaster 127.0.0.1 26380 e43e1bc4459a782d2049f8ab1dd8938e17c90ced

启动sentinel，查看哨兵信息：

• sentinel6380.conf

protected-mode no
port 26380


daemonize yes
pidfile "/var/run/redis-sentinel_26379.pid"
logfile "/usr/local/redis-6.2.14/logs/redis-sentinel_26379.log"
dir "/private/tmp"


sentinel monitor mymaster 127.0.0.1 6379 2


sentinel announce-hostnames no
# Generated by CONFIG REWRITE
user default on nopass ~* &* +@all
sentinel myid c384816840b671b2f194ebd417458c6bbd08230c
sentinel config-epoch mymaster 0
sentinel leader-epoch mymaster 0
sentinel current-epoch 0
sentinel known-replica mymaster 127.0.0.1 6381
sentinel known-replica mymaster 127.0.0.1 6380
sentinel known-sentinel mymaster 127.0.0.1 26381 789f7ad2247aa6104665ced751c1956e87ec175b
sentinel known-sentinel mymaster 127.0.0.1 26380 e43e1bc4459a782d2049f8ab1dd8938e17c90ced

启动sentinel，查看哨兵信息：

• sentinel6381.conf

protected-mode no
port 26381


daemonize yes
pidfile "/var/run/redis-sentinel_26379.pid"
logfile "/usr/local/redis-6.2.14/logs/redis-sentinel_26379.log"
dir "/private/tmp"


sentinel monitor mymaster 127.0.0.1 6379 2


sentinel announce-hostnames no
# Generated by CONFIG REWRITE
user default on nopass ~* &* +@all
sentinel myid c384816840b671b2f194ebd417458c6bbd08230c
sentinel config-epoch mymaster 0
sentinel leader-epoch mymaster 0
sentinel current-epoch 0
sentinel known-replica mymaster 127.0.0.1 6381
sentinel known-replica mymaster 127.0.0.1 6380
sentinel known-sentinel mymaster 127.0.0.1 26381 789f7ad2247aa6104665ced751c1956e87ec175b
sentinel known-sentinel mymaster 127.0.0.1 26380 e43e1bc4459a782d2049f8ab1dd8938e17c90ced

启动sentinel，查看哨兵信息：

故障转移测试

redis日志

• 我们kill掉原Master进程，即6379的redis-server，看日志

• 看下6380的redis-server日志

06 Sep 2024 15:49:18.869：开始断开和Master进程的连接，接着持续报错说复制失败，不断地重试

（中间有30s的重试）

06 Sep 2024 15:49:49.205 * MASTER MODE enabled，即6380实例被sentinel选举为Master节点

• 看下6381的redis-server日志

06 Sep 2024 15:49:18.870 # Error condition on socket for SYNC: Connection refused开始断开和Master进程的连接，接着持续报错说复制失败，不断地重试

（中间有30s的重试）

06 Sep 2024 15:49:49.262 * REPLICAOF 127.0.0.1:6380 enabled ，即6380实例被sentinel选举为Master节点后，6381实例也接受现实，开始从6380实例进行数据同步

redis-sentinel日志

让我们进入到之前配置好的文件夹

• redis-sentinel_26379进程日志

• redis-sentinel_26380进程日志

• redis-sentinel_26381进程日志

故障恢复

• 重新启动6379实例

• 通过26379-sentinel，虽然原Master重启了，但目前Master还是6380

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