02.Redis主从集群的Sentinel配置

阅读目录

• 开始
• 1.集群环境
• 2.配置并启动Redis主从集群
• 3.配置sentinel集群并启动
• 4.测试sentinel集群

 

回到顶部

1.集群环境

1.Linux服务器列表

使用4台CentOS Linux服务器搭建环境，其IP地址如下：

1. 192.168.110.100
2. 192.168.110.101
3. 192.168.110.102
4. 192.168.110.103

2.Redis服务部署环境

192.168.110.100

启动多个Redis sentinel服务，构成Redis sentinel集群

192.168.110.101

启动Redis服务，设置成主节点

192.168.110.102

启动Redis服务，设置成192.168.110.101的从节点

192.168.110.103

启动Redis服务，设置成192.168.110.101的从节点

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2.配置并启动Redis主从集群

1.修改redis.conf配置文件

主节点的redis配置文件使用默认的配置文件就可以了，从节点的redis配置文件修改如下：

1. # Master-Slave replication. Use slaveof to make a Redis instance a copy of
2. # another Redis server. A few things to understand ASAP about Redis replication.
3. #
4. # 1) Redis replication is asynchronous, but you can configure a master to
5. # stop accepting writes if it appears to be not connected with at least
6. # a given number of slaves.
7. # 2) Redis slaves are able to perform a partial resynchronization with the
8. # master if the replication link is lost for a relatively small amount of
9. # time. You may want to configure the replication backlog size (see the next
10. # sections of this file) with a sensible value depending on your needs.
11. # 3) Replication is automatic and does not need user intervention. After a
12. # network partition slaves automatically try to reconnect to masters
13. # and resynchronize with them.
14. #
15. # 主从同步。通过 slaveof 配置来实现Redis实例的备份。
16. # 注意，这里是本地从远端复制数据。也就是说，本地可以有不同的数据库文件、绑定不同的IP、监听不同的端口。
17. #
18. # slaveof <masterip> <masterport>
19. slaveof 192.168.110.1016379

注意:两台从节点都要改。

2.启动Redis主从集群

先启动192.168.110.101主节点，使用默认配置，脚本：

1. [wch@localhost bin]$ ./redis-server

再启动192.168.110.102和192.168.110.103从节点，使用刚才的配置，脚本：

1. ./redis-server redis.conf

3.查看集群

192.168.110.101主节点Replication信息

1. [wch@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication
2. # Replication
3. role:master
4. connected_slaves:2
5. slave0:ip=192.168.110.102,port=6379,state=online,offset=659,lag=1
6. slave1:ip=192.168.110.103,port=6379,state=online,offset=659,lag=0
7. master_repl_offset:659
8. repl_backlog_active:1
9. repl_backlog_size:1048576
10. repl_backlog_first_byte_offset:2
11. repl_backlog_histlen:658

192.168.110.102从节点Replication信息

1. [wch@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication
2. # Replication
3. role:slave
4. master_host:192.168.110.101
5. master_port:6379
6. master_link_status:up
7. master_last_io_seconds_ago:3
8. master_sync_in_progress:0
9. slave_repl_offset:701
10. slave_priority:100
11. slave_read_only:1
12. connected_slaves:0
13. master_repl_offset:0
14. repl_backlog_active:0
15. repl_backlog_size:1048576
16. repl_backlog_first_byte_offset:0
17. repl_backlog_histlen:0

192.168.110.103从节点Replication信息

1. [wch@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication
2. # Replication
3. role:slave
4. master_host:192.168.110.101
5. master_port:6379
6. master_link_status:up
7. master_last_io_seconds_ago:9
8. master_sync_in_progress:0
9. slave_repl_offset:715
10. slave_priority:100
11. slave_read_only:1
12. connected_slaves:0
13. master_repl_offset:0
14. repl_backlog_active:0
15. repl_backlog_size:1048576
16. repl_backlog_first_byte_offset:0
17. repl_backlog_histlen:0

此时，存储到192.168.110.101主节点的数据，在从节点中都可以查询到。从节点会备份主节点的数据。

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3.配置sentinel集群并启动

1.创建sentinel.conf配置文件

1. port 26379
2. # sentinel announce-ip <ip>
3. # sentinel announce-port <port>
4. dir /tmp
6. ################################# master001 #################################
7. sentinel monitor master001 192.168.110.10163792
8. # sentinel auth-pass <master-name> <password>
9. sentinel down-after-milliseconds master001 30000
10. sentinel parallel-syncs master001 1
11. sentinel failover-timeout master001 180000
12. # sentinel notification-script <master-name> <script-path>
13. # sentinel client-reconfig-script <master-name> <script-path>
15. # 可以配置多个master节点
16. ################################# master002 #################################

配置文件说明：

1. port :当前Sentinel服务运行的端口

 

2. dir : Sentinel服务运行时使用的临时文件夹

 

3.sentinel monitor master001 192.168.110.10163792:Sentinel去监视一个名为master001的主redis实例，这个主实例的IP地址为本机地址192.168.110.101，端口号为6379，而将这个主实例判断为失效至少需要2个 Sentinel进程的同意，只要同意Sentinel的数量不达标，自动failover就不会执行

 

4.sentinel down-after-milliseconds master001 30000:指定了Sentinel认为Redis实例已经失效所需的毫秒数。当实例超过该时间没有返回PING，或者直接返回错误，那么Sentinel将这个实例标记为主观下线。只有一个 Sentinel进程将实例标记为主观下线并不一定会引起实例的自动故障迁移：只有在足够数量的Sentinel都将一个实例标记为主观下线之后，实例才会被标记为客观下线，这时自动故障迁移才会执行

 

5.sentinel parallel-syncs master001 1：指定了在执行故障转移时，最多可以有多少个从Redis实例在同步新的主实例，在从Redis实例较多的情况下这个数字越小，同步的时间越长，完成故障转移所需的时间就越长

 

6.sentinel failover-timeout master001 180000：如果在该时间（ms）内未能完成failover操作，则认为该failover失败

 

7.sentinel notification-script <master-name> <script-path>：指定sentinel检测到该监控的redis实例指向的实例异常时，调用的报警脚本。该配置项可选，但是很常用

2.启动sentinel集群

创建3个sentinel.conf配置文件：sentinel001.conf、sentinel002.conf、sentinel003.conf并修改端口号分别为：26379、36379、46379，并启动服务：

1. ./redis-sentinel sentinel001.conf
2. ./redis-sentinel sentinel002.conf
3. ./redis-sentinel sentinel003.conf

启动三个sentinel服务后会在其控制台看到如下信息：

./redis-sentinel sentinel001.conf，端口：26379

1. [7743]01Oct06:20:38.162# Sentinel runid is ba6c42e1accc31290e11d5876275e1562564295d
2. [7743]01Oct06:20:38.162# +monitor master master001 192.168.110.101 6379 quorum 2
3. [7743]01Oct06:20:39.110*+slave slave 192.168.110.102:6379192.168.110.1026379@ master001 192.168.110.1016379
4. [7743]01Oct06:20:39.111*+slave slave 192.168.110.103:6379192.168.110.1036379@ master001 192.168.110.1016379
5. [7743]01Oct06:25:07.595*+sentinel sentinel 192.168.110.100:36379192.168.110.10036379@ master001 192.168.110.1016379
6. [7743]01Oct06:26:11.170*+sentinel sentinel 192.168.110.100:46379192.168.110.10046379@ master001 192.168.110.1016379

./redis-sentinel sentinel002.conf，端口：36379

1. [7795]01Oct06:25:05.538# Sentinel runid is 52c14768b15837fb601b26328acf150c6bd30682
2. [7795]01Oct06:25:05.538# +monitor master master001 192.168.110.101 6379 quorum 2
3. [7795]01Oct06:25:06.505*+slave slave 192.168.110.102:6379192.168.110.1026379@ master001 192.168.110.1016379
4. [7795]01Oct06:25:06.515*+slave slave 192.168.110.103:6379192.168.110.1036379@ master001 192.168.110.1016379
5. [7795]01Oct06:25:07.557*+sentinel sentinel 192.168.110.100:26379192.168.110.10026379@ master001 192.168.110.1016379
6. [7795]01Oct06:26:11.168*+sentinel sentinel 192.168.110.100:46379192.168.110.10046379@ master001 192.168.110.1016379

./redis-sentinel sentinel003.conf，端口：46379

1. [7828]01Oct06:26:09.076# Sentinel runid is c8509594be4a36660b2122b3b81f4f74060c9b04
2. [7828]01Oct06:26:09.076# +monitor master master001 192.168.110.101 6379 quorum 2
3. [7828]01Oct06:26:10.063*+slave slave 192.168.110.102:6379192.168.110.1026379@ master001 192.168.110.1016379
4. [7828]01Oct06:26:10.071*+slave slave 192.168.110.103:6379192.168.110.1036379@ master001 192.168.110.1016379
5. [7828]01Oct06:26:11.516*+sentinel sentinel 192.168.110.100:26379192.168.110.10026379@ master001 192.168.110.1016379
6. [7828]01Oct06:26:11.674*+sentinel sentinel 192.168.110.100:36379192.168.110.10036379@ master001 192.168.110.1016379

每个sentinel服务能知道其他所有的服务！

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4.测试sentinel集群

1.停止192.168.110.101主节点

停止192.168.110.101Redis主节点后，在查看Replication信息如下：

1. [wch@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication
2. Could not connect to Redis at 192.168.110.101:6379:Connection refused
4. [wch@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication
5. # Replication
6. role:slave
7. master_host:192.168.110.103
8. master_port:6379
9. master_link_status:up
10. master_last_io_seconds_ago:1
11. master_sync_in_progress:0
12. slave_repl_offset:29128
13. slave_priority:100
14. slave_read_only:1
15. connected_slaves:0
16. master_repl_offset:0
17. repl_backlog_active:0
18. repl_backlog_size:1048576
19. repl_backlog_first_byte_offset:0
20. repl_backlog_histlen:0
22. [wch@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication
23. # Replication
24. role:master
25. connected_slaves:1
26. slave0:ip=192.168.110.102,port=6379,state=online,offset=30456,lag=1
27. master_repl_offset:30456
28. repl_backlog_active:1
29. repl_backlog_size:1048576
30. repl_backlog_first_byte_offset:2
31. repl_backlog_histlen:30455
32. [wch@localhost bin]$

发现192.168.110.101Redis主节点已经不能连接，192.168.110.103成了主节点！

2.再启动192.168.110.101主节点

再启动192.168.110.101Redis主节点后，在查看Replication信息如下：

1. ### 启动脚本，仍然使用默认配置
2. [wch@localhost bin]$ ./redis-server
4. [wch@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication
5. # Replication
6. role:slave
7. master_host:192.168.110.103
8. master_port:6379
9. master_link_status:up
10. master_last_io_seconds_ago:1
11. master_sync_in_progress:0
12. slave_repl_offset:57657
13. slave_priority:100
14. slave_read_only:1
15. connected_slaves:0
16. master_repl_offset:0
17. repl_backlog_active:0
18. repl_backlog_size:1048576
19. repl_backlog_first_byte_offset:0
20. repl_backlog_histlen:0
21.  
22. [wch@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication
23. # Replication
24. role:slave
25. master_host:192.168.110.103
26. master_port:6379
27. master_link_status:up
28. master_last_io_seconds_ago:0
29. master_sync_in_progress:0
30. slave_repl_offset:60751
31. slave_priority:100
32. slave_read_only:1
33. connected_slaves:0
34. master_repl_offset:0
35. repl_backlog_active:0
36. repl_backlog_size:1048576
37. repl_backlog_first_byte_offset:0
38. repl_backlog_histlen:0
39.  
40. [wch@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication
41. # Replication
42. role:master
43. connected_slaves:2
44. slave0:ip=192.168.110.102,port=6379,state=online,offset=63247,lag=1
45. slave1:ip=192.168.110.101,port=6379,state=online,offset=63247,lag=1
46. master_repl_offset:63393
47. repl_backlog_active:1
48. repl_backlog_size:1048576
49. repl_backlog_first_byte_offset:2
50. repl_backlog_histlen:63392
51. [wch@localhost bin]$

发现192.168.110.101节点启动后还再集群中，只不过成了从节点，192.168.110.103仍然是主节点，但是现在又有两个从节点了！

3.只留下一个sentinel服务，再停止192.168.110.103主节点，查看Redis集群是否出现新的主节点

停止sentinel服务，只留下一个sentinel服务，再停止Redis主节点，查看Replication信息如下：

1. [wch@localhost bin]$ ./redis-cli -h 192.168.110.101 info Replication
2. # Replication
3. role:slave
4. master_host:192.168.110.103
5. master_port:6379
6. master_link_status:down
7. master_last_io_seconds_ago:-1
8. master_sync_in_progress:0
9. slave_repl_offset:184231
10. master_link_down_since_seconds:43
11. slave_priority:100
12. slave_read_only:1
13. connected_slaves:0
14. master_repl_offset:0
15. repl_backlog_active:0
16. repl_backlog_size:1048576
17. repl_backlog_first_byte_offset:0
18. repl_backlog_histlen:0
20. [wch@localhost bin]$ ./redis-cli -h 192.168.110.102 info Replication
21. # Replication
22. role:slave
23. master_host:192.168.110.103
24. master_port:6379
25. master_link_status:down
26. master_last_io_seconds_ago:-1
27. master_sync_in_progress:0
28. slave_repl_offset:184231
29. master_link_down_since_seconds:52
30. slave_priority:100
31. slave_read_only:1
32. connected_slaves:0
33. master_repl_offset:0
34. repl_backlog_active:0
35. repl_backlog_size:1048576
36. repl_backlog_first_byte_offset:0
37. repl_backlog_histlen:0
39. [wch@localhost bin]$ ./redis-cli -h 192.168.110.103 info Replication
40. Could not connect to Redis at 192.168.110.103:6379:Connection refused

发现192.168.110.103主节点已经不能连接了，也不存在Redis主节点，集群中无主节点了！！！分析原因是：sentinel.conf配置的sentinel monitor master001 192.168.110.10163792最后一个参数是2导致，若是但节点此配置的最后一个参数要使用是1。(此原因我已证实)

注意：在生产环境下建议sentinel节点的数量能在3个以上，并且最好不要在同一台机器上(使用同一网卡)。

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