Centos7搭建Redis主从复制及sentinel监控

迷南。 2023-05-29 05:11 25阅读 0赞

### Centos7搭建Redis主从复制及sentinel监控 ###

*  主从复制
 *  sentinel监控，实现故障转移failover

# 主从复制 #

本文介绍如何搭建Redis一主二从环境，需要先准备3个Redis单实例节点环境。  
单实例节点环境搭建请参考：[Centos7安装Redis单节点 https://blog.csdn.net/iceliooo/article/details/102892062][Centos7_Redis_ https_blog.csdn.net_iceliooo_article_details_102892062]

<table> 
 <thead> 
  <tr> 
   <th>IP</th> 
   <th>角色：端口</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>192.168.56.105</td> 
   <td>Master：6379</td> 
  </tr> 
  <tr> 
   <td>192.168.56.106</td> 
   <td>replica：6379</td> 
  </tr> 
  <tr> 
   <td>192.168.56.107</td> 
   <td>replica：6379</td> 
  </tr> 
 </tbody> 
</table>

修改106及107节点redis.conf配置，添加如下配置信息：

286 # replicaof <masterip> <masterport>
    287 replicaof 192.168.56.105 6379

重启105，106， 107 节点Redis服务，查看主从复制状态：  
105Master节点：

[root@k8s-master src]# redis-server ../redis.conf
    23141:C 04 Nov 2019 14:37:31.847 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
    23141:C 04 Nov 2019 14:37:31.847 # Redis version=5.0.5, bits=64, commit=00000000, modified=0, pid=23141, just started
    23141:C 04 Nov 2019 14:37:31.847 # Configuration loaded
    [root@k8s-master src]# redis-cli
    127.0.0.1:6379> info replication
    NOAUTH Authentication required.
    127.0.0.1:6379> auth ******
    OK
    127.0.0.1:6379> info replication
    # Replication
    role:master
    connected_slaves:0
    master_replid:c3bda75e828e43caee07f27dc191f98e661b82c2
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:0
    second_repl_offset:-1
    repl_backlog_active:0
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:0
    repl_backlog_histlen:0

106 replica节点：

[root@k8s-node1 src]# redis-server ../redis.conf
    13197:C 04 Nov 2019 14:38:40.254 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
    13197:C 04 Nov 2019 14:38:40.254 # Redis version=5.0.5, bits=64, commit=00000000, modified=0, pid=13197, just started
    13197:C 04 Nov 2019 14:38:40.254 # Configuration loaded
    [root@k8s-node1 src]# redis-cli 
    127.0.0.1:6379> info replication
    NOAUTH Authentication required.
    127.0.0.1:6379> auth ******
    OK
    127.0.0.1:6379> info repilication
    127.0.0.1:6379> info replication
    # Replication
    role:slave
    master_host:192.168.56.105
    master_port:6379
    master_link_status:down
    master_last_io_seconds_ago:-1
    master_sync_in_progress:0
    slave_repl_offset:1
    master_link_down_since_seconds:1572849566
    slave_priority:100
    slave_read_only:1
    connected_slaves:0
    master_replid:c1b5f8a15f72d059bc1d523a12c4a4380391c35d
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:0
    second_repl_offset:-1
    repl_backlog_active:0
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:0
    repl_backlog_histlen:0

发现主从配置失败，主要是因为Master节点配置了访问密码，所以需要在replica节点配置Master节点的访问秘密：

294 # masterauth <master-password>
    295 masterauth ******

重启Master及replica节点，主从配置成功：

127.0.0.1:6379> info replication
    # Replication
    role:master
    connected_slaves:2
    slave0:ip=192.168.56.106,port=6379,state=online,offset=254,lag=1
    slave1:ip=192.168.56.107,port=6379,state=online,offset=254,lag=1
    master_replid:c4b26a9a991c54e3110d3cf9479d997937532002
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:254
    second_repl_offset:-1
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:254

127.0.0.1:6379> info replication
    # Replication
    role:slave
    master_host:192.168.56.105
    master_port:6379
    master_link_status:up
    master_last_io_seconds_ago:2
    master_sync_in_progress:0
    slave_repl_offset:56
    slave_priority:100
    slave_read_only:1
    connected_slaves:0
    master_replid:c4b26a9a991c54e3110d3cf9479d997937532002
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:56
    second_repl_offset:-1
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:56

Master节点执行命令，replica节点成功接收

127.0.0.1:6379> set iceliooo male
    OK
    127.0.0.1:6379>

从节点默认为自读

127.0.0.1:6379> get iceliooo
    "male"
    127.0.0.1:6379> set iceliooo male
    (error) READONLY You can't write against a read only replica.
    127.0.0.1:6379>

# sentinel监控，实现故障转移failover #

主从复制解决了数据备份问题，提升了性能，但Master节点不可用，将出现单点故障，需要手动切换Master节点，费时费力，还会造成服务不可用问题。  
下面介绍如何通过sentinel实现Master自动切换。  
sentinel监控主从集群中所有Redis服务节点，sentinel本身也会存在单点故障问题，sentinel通过相互监控来解决。sentinel本身没有主从之分。

Redis主从及Sentinel部署分布

<table> 
 <thead> 
  <tr> 
   <th>IP</th> 
   <th>角色：端口</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>192.168.56.105</td> 
   <td>Master：6379/sentinel：26379</td> 
  </tr> 
  <tr> 
   <td>192.168.56.106</td> 
   <td>replica：6379 /sentinel：26379</td> 
  </tr> 
  <tr> 
   <td>192.168.56.107</td> 
   <td>replica：6379/sentinel：26379</td> 
  </tr> 
 </tbody> 
</table>

修改sentinel.conf配置文件

[root@k8s-master redis-5.0.5]# cp sentinel.conf sentinel.conf.bak
    [root@k8s-master redis-5.0.5]# vi sentinel.conf

主要修改如下配置，其它使用默认值：

daemonize yes
    port 16379
    protected-mode no
    dir "/usr/local/software/redis-5.0.5/sentinel-temp"
    sentinel monitor redis-master 192.168.56.105 6379 2

启动3台服务器的redis服务和sentinel服务

[root@k8s-master redis-5.0.5]# cd src/
    [root@k8s-master src]# redis-sentinel ../sentinel.conf
    2489:X 04 Nov 2019 17:12:28.225 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
    2489:X 04 Nov 2019 17:12:28.225 # Redis version=5.0.5, bits=64, commit=00000000, modified=0, pid=2489, just started
    2489:X 04 Nov 2019 17:12:28.225 # Configuration loaded
    [root@k8s-master src]# ps -ef|grep redis
    root      2490     1  0 17:12 ?        00:00:00 redis-sentinel *:16379 [sentinel]
    root      3064 11611  0 17:13 pts/1    00:00:00 grep --color=auto redis
    root     29488     1  0 14:50 ?        00:00:09 redis-server *:6379
    [root@k8s-master src]#

模拟Master故障：

106上查看集群状态：

127.0.0.1:6379> auth centos
    OK
    127.0.0.1:6379> info replication
    # Replication
    role:slave
    master_host:192.168.56.105
    master_port:6379
    master_link_status:up
    master_last_io_seconds_ago:7
    master_sync_in_progress:0
    slave_repl_offset:12465
    slave_priority:100
    slave_read_only:1
    connected_slaves:0
    master_replid:c4b26a9a991c54e3110d3cf9479d997937532002
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:12465
    second_repl_offset:-1
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:12465
    127.0.0.1:6379>

关闭Master节点：

127.0.0.1:6379> SHUTDOWN
    not connected>

再次查看106上集群状态，30秒之后发现master节点切换失败：

127.0.0.1:6379> info replication
    # Replication
    role:slave
    master_host:192.168.56.105
    master_port:6379
    master_link_status:down
    master_last_io_seconds_ago:-1
    master_sync_in_progress:0
    slave_repl_offset:12605
    master_link_down_since_seconds:35
    slave_priority:100
    slave_read_only:1
    connected_slaves:0
    master_replid:c4b26a9a991c54e3110d3cf9479d997937532002
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:12605
    second_repl_offset:-1
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:12605
    127.0.0.1:6379>

失败原因主要是没有在sentinel.conf配置文件中配置Redis集群节点的访问密码（**这里要求集群中每个节点的访问密码必须一致**）

121 sentinel monitor mymaster 192.168.56.107 6379 2
    122 sentinel auth-pass mymaster ******

这里还需要注意，“sentinel auth-pass mymaster \*\*\*\*\*\*” 必须配置在“sentinel monitor mymaster 192.168.56.107 6379 2” 之后，否则会出现如下异常：

[root@k8s-master src]# redis-sentinel ../sentinel.conf
    
    *** FATAL CONFIG FILE ERROR ***
    Reading the configuration file, at line 104
    >>> 'sentinel auth-pass mymaster ******'
    No such master with specified name.

重新启动各个节点的redis-sentinel服务及redis服务，106上查看集群状态：

127.0.0.1:6379> info replication
    # Replication
    role:slave
    master_host:192.168.56.105
    master_port:6379
    master_link_status:up
    master_last_io_seconds_ago:1
    master_sync_in_progress:0
    slave_repl_offset:1596
    slave_priority:100
    slave_read_only:1
    connected_slaves:0
    master_replid:09787ba9f25f74e8caac6c07808997c7d3d4a421
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:1596
    second_repl_offset:-1
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:1596

关闭Master节点，模拟Master节点故障：

127.0.0.1:6379> info replication
    # Replication
    role:master
    connected_slaves:2
    slave0:ip=192.168.56.106,port=6379,state=online,offset=6786,lag=0
    slave1:ip=192.168.56.107,port=6379,state=online,offset=6786,lag=1
    master_replid:09787ba9f25f74e8caac6c07808997c7d3d4a421
    master_replid2:0000000000000000000000000000000000000000
    master_repl_offset:6786
    second_repl_offset:-1
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:6786
    127.0.0.1:6379> SHUTDOWN
    not connected>

30秒后，106上查看集群状态，切换成功，107成为新的Master节点：

127.0.0.1:6379> info replication
    # Replication
    role:slave
    master_host:192.168.56.107
    master_port:6379
    master_link_status:up
    master_last_io_seconds_ago:0
    master_sync_in_progress:0
    slave_repl_offset:11842
    slave_priority:100
    slave_read_only:1
    connected_slaves:0
    master_replid:569347a188791772e9f7ff3fa11048d0e6a86b01
    master_replid2:09787ba9f25f74e8caac6c07808997c7d3d4a421
    master_repl_offset:11842
    second_repl_offset:8517
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:11842

启动105redis节点，模拟原Master节点恢复，新Master中恢复到两个replica节点：

127.0.0.1:6379> info replication
    # Replication
    role:master
    connected_slaves:2
    slave0:ip=192.168.56.106,port=6379,state=online,offset=478823,lag=1
    slave1:ip=192.168.56.105,port=6379,state=online,offset=478966,lag=0
    master_replid:569347a188791772e9f7ff3fa11048d0e6a86b01
    master_replid2:09787ba9f25f74e8caac6c07808997c7d3d4a421
    master_repl_offset:478966
    second_repl_offset:8517
    repl_backlog_active:1
    repl_backlog_size:1048576
    repl_backlog_first_byte_offset:1
    repl_backlog_histlen:478966

[Centos7_Redis_ https_blog.csdn.net_iceliooo_article_details_102892062]: https://blog.csdn.net/iceliooo/article/details/102892062