利用Sentinel实现Redis主从切换

利用Sentinel(哨兵)实现Redis集群的故障自主切换

首先部署redis主从集群，主要安装过程:

cd redis
make
make install

主要看配置文件:

master：

bind 0.0.0.0

port 6801

logfile "./redis.log"

requirepass 12345678

masterauth 12345678   ＃主从密码，主变为从时，以从的身份去同步主节点

slave:

bind 0.0.0.0

port 6802

logfile "./redis.log"

requirepass 12345678

masterauth 12345678

slaveof 172.17.0.2 6801

sentinel：

bind 0.0.0.0

port 26379

dir ./

logfile "./sentinel.log"
 
...
sentinel monitor master1 172.17.0.2 6801 1
sentinel down-after-milliseconds master1 10000
sentinel failover-timeout master1 900000
sentinel config-epoch master1 4317
sentinel leader-epoch master1 4317
sentinel auth-pass master1 12345678

启动redis+sentinel集群，查看节点信息如下:

master：

slave:

可以看出主从已经生效，现在把master(172.17.0.2 6801)关掉，查看sentinel日志:

1:X 25 May 18:59:39.096 # +sdown master master1 172.17.0.2 6801
1:X 25 May 18:59:39.096 # +odown master master1 172.17.0.2 6801 #quorum 1/1
1:X 25 May 18:59:39.096 # +new-epoch 4320
1:X 25 May 18:59:39.096 # +try-failover master master1 172.17.0.2 6801
1:X 25 May 18:59:39.145 # +vote-for-leader 5a30725736229497d4f5f0ef3502462dd683f02e 4320
1:X 25 May 18:59:39.145 # +elected-leader master master1 172.17.0.2 6801
1:X 25 May 18:59:39.145 # +failover-state-select-slave master master1 172.17.0.2 6801
1:X 25 May 18:59:39.217 # +selected-slave slave 172.17.0.3:6802 172.17.0.3 6802 @ master1 172.17.0.2 6801
1:X 25 May 18:59:39.217 * +failover-state-send-slaveof-noone slave 172.17.0.3:6802 172.17.0.3 6802 @ master1 172.17.0.2 6801
1:X 25 May 18:59:39.307 * +failover-state-wait-promotion slave 172.17.0.3:6802 172.17.0.3 6802 @ master1 172.17.0.2 6801
1:X 25 May 18:59:39.312 # +promoted-slave slave 172.17.0.3:6802 172.17.0.3 6802 @ master1 172.17.0.2 6801
1:X 25 May 18:59:39.312 # +failover-state-reconf-slaves master master1 172.17.0.2 6801
1:X 25 May 18:59:39.359 # +failover-end master master1 172.17.0.2 6801
1:X 25 May 18:59:39.359 # +switch-master master1 172.17.0.2 6801 172.17.0.3 6802
1:X 25 May 18:59:39.359 * +slave slave 172.17.0.2:6801 172.17.0.2 6801 @ master1 172.17.0.3 6802
1:X 25 May 18:59:49.419 # +sdown slave 172.17.0.2:6801 172.17.0.2 6801 @ master1 172.17.0.3 6802

可以看到，从节点172.17.0.3 6802 已经成为master:

现在启动172.17.0.2:6801,sentinel日志如下:

1:X 25 May 19:03:14.929 # -sdown slave 172.17.0.2:6801 172.17.0.2 6801 @ master1 172.17.0.3 6802
1:X 25 May 19:03:24.903 * +convert-to-slave slave 172.17.0.2:6801 172.17.0.2 6801 @ master1 172.17.0.3 6802

连接到redis后查看集群信息如下:

可以看到，之前的master(172.17.0.2 6801) 已经成为了slave。