一步步搭建Redis主从集群和哨兵集群

redis下载

把官网的这个先粘过来…

Installation

Download, extract and compile Redis with:
$ wget http://download.redis.io/releases/redis-5.0.5.tar.gz
$ tar xzf redis-5.0.5.tar.gz
$ cd redis-5.0.5
$ make
The binaries that are now compiled are available in the src directory. Run Redis with:
$ src/redis-server
You can interact with Redis using the built-in client:
$ src/redis-cli
redis> set foo bar
OK
redis> get foo
"bar"

[root@xinyeshuaiqi ~]# wget http://download.redis.io/releases/redis-4.0.14.tar.gz
–2019-10-29 12:22:25– http://download.redis.io/releases/redis-4.0.14.tar.gz
Resolving download.redis.io (download.redis.io)… 109.74.203.151
Connecting to download.redis.io (download.redis.io)|109.74.203.151|:80… connected.
HTTP request sent, awaiting response… 200 OK
Length: 1740967 (1.7M) [application/x-gzip]
Saving to: ‘redis-4.0.14.tar.gz’

redis安装与启动

我直接用的 redis-3.2.12

得到压缩包，tar -zxvf 进行解压

然后进入解压后的目录

make && make PREFIX=/root/redis install

进行redis源码编译并指定安装目录

[root@xinyeshuaiqi ~]# mkdir myRedis

[root@xinyeshuaiqi myRedis]# mkdir 638{1,2,3} 

[root@xinyeshuaiqi myRedis]# cd 6381

6381、6382、6383是我为后续redis主从集群创建的目录,先不管

redis-server --port 6381 是启动redis且指定端口6381

[root@xinyeshuaiqi 6381]# redis-server --port 6381
                _._                                                  
           _.-``__ ''-._                                             
      _.-``    `.  `_.  ''-._           Redis 3.2.12 (00000000/0) 64 bit
  .-`` .-```.  ```\/    _.,_ ''-._                                   
 (    '      ,       .-`  | `,    )     Running in standalone mode
 |`-._`-...-` __...-.``-._|'` _.-'|     Port: 6381
 |    `-._   `._    /     _.-'    |     PID: 1350
  `-._    `-._  `-./  _.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |           http://redis.io        
  `-._    `-._`-.__.-'_.-'    _.-'                                   
 |`-._`-._    `-.__.-'    _.-'_.-'|                                  
 |    `-._`-._        _.-'_.-'    |                                  
  `-._    `-._`-.__.-'_.-'    _.-'                                   
      `-._    `-.__.-'    _.-'                                       
          `-._        _.-'                                           
              `-.__.-'                                               

1350:M 29 Oct 12:26:08.876 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
1350:M 29 Oct 12:26:08.876 # Server started, Redis version 3.2.12
1350:M 29 Oct 12:26:08.876 # WARNING overcommit_memory is set to 0! Background save may fail under low memory condition. To fix this issue add 'vm.overcommit_memory = 1' to /etc/sysctl.conf and then reboot or run the command 'sysctl vm.overcommit_memory=1' for this to take effect.
1350:M 29 Oct 12:26:08.876 # WARNING you have Transparent Huge Pages (THP) support enabled in your kernel. This will create latency and memory usage issues with Redis. To fix this issue run the command 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' as root, and add it to your /etc/rc.local in order to retain the setting after a reboot. Redis must be restarted after THP is disabled.
1350:M 29 Oct 12:26:08.876 * The server is now ready to accept connections on port 6381

设置后台运行

但默认后台进程是阻塞形式的

我们需要去配置redis以后台形式运行

修改redis.config （/root/redis/redis.config）

redis客户端

redis-cli -p 端口号 (指定连接的port)

./redis-cli -h ip地址 -p 端口号 (在本机连接-h可以省掉)

关闭redis

我们把刚才启动的redis server全关掉

优雅关闭：redis-cli shutdown （有时候不好使）

粗鲁关闭：

[root@xinyeshuaiqi 6381]# ps -ef | grep redis
root      1350     1  0 12:26 ?        00:00:03 redis-server *:6381
root      4142     1  0 13:19 ?        00:00:02 redis-server *:6382
root      8060  6728  0 14:31 pts/3    00:00:00 grep --color=auto redis
[root@xinyeshuaiqi 6381]# kill -9 1350
[root@xinyeshuaiqi 6381]# ps -ef | grep redis
root      4142     1  0 13:19 ?        00:00:02 redis-server *:6382
root      8111  6728  0 14:32 pts/3    00:00:00 grep --color=auto redis

redis主从集群

依然进入上面我们创建的6381目录

redis-server /root/redis/redis.conf --port 6381

端口号为6381

进入6382目录

redis-server /root/redis/redis.conf --port 6382 --slaveof 127.0.0.1 6381

启动另一个redis实例指定为6381的从,端口号为6382

进入6383目录

redis-server /root/redis/redis.conf --port 6383 --slaveof 127.0.0.1 6381

启动另一个redis实例指定为6381的从,端口号为6383

[root@xinyeshuaiqi 6383]# ps -ef | grep redis
root      8407     1  0 14:38 ?        00:00:00 redis-server *:6381
root      8730     1  0 14:44 ?        00:00:00 redis-server *:6382
root      8742     1  0 14:44 ?        00:00:00 redis-server *:6383
root      8792  6728  0 14:45 pts/3    00:00:00 grep --color=auto redis

[root@xinyeshuaiqi 6381]# ls
dump.rdb

6381、6382、6383目录生成了dump.rdb文件

测试一波

先连接redis主

使用 info replication查看主从信息

我们在主set 一个值，再去从看看有没有取到

127.0.0.1:6381> set mykey haha
OK
127.0.0.1:6381> get mykey
"haha"

[root@xinyeshuaiqi 6383]# redis-cli -p 6382
127.0.0.1:6382> keys *
1) "mykey"
127.0.0.1:6382> 
127.0.0.1:6382> 
127.0.0.1:6382> get mykey
"haha"

舒服了，主从数据同步

我们再来试试从支不支持写命令

127.0.0.1:6382> set key1 hehe
(error) READONLY You can't write against a read only slave.

结论：

redis主从集群支持一主多从，主从数据同步，

主支持读写、从只支持读操作

原理：

1. slave第一次或者重连到master上以后，会向master发送一个SYNC的命令

2. master收到SYNC的时候，会做两件事：

1) 执行bgsave（rdb的快照文件）

2) master会把新收到的修改命令存入到缓冲区

拓展：

Replication：镜像

写命令退化到单点，查询主从一起负责，写命令单单由主负责，单点瓶颈

而且如果主挂了怎么办？又不支持动态选举

因此redis 引入哨兵机制

哨兵集群

哨兵管理redis服务器

redis-sentinel

哨兵也有集群，他只知道主，通过主可以知道主的从

我们先看一个图直观的感受一哈

如果有3个哨兵搭建一个集群，监控着redis集群，

并和redis master保持心跳,如果有2个哨兵（过半）都收不到一个master的心跳，

就认为该master挂了，slave上来替代成为master

上面的图只是给大家一个直观印象，我们回到本例：

上面我们不是启了一主多从吗，3台redis实例

我们再启3个哨兵，监控我们的redis集群

下面我们开始搭建哨兵集群

在root下创建一个目录 myRedis-sentinel

[root@xinyeshuaiqi redis-3.2.12]# pwd
/root/redis-3.2.12
[root@xinyeshuaiqi redis-3.2.12]# ls
00-RELEASENOTES  BUGS  CONTRIBUTING  COPYING  deps  INSTALL  Makefile  MANIFESTO  README.md  redis  redis.conf  runtest  runtest-cluster  runtest-sentinel  sentinel.conf  src  tests  utils
[root@xinyeshuaiqi redis-3.2.12]# 
[root@xinyeshuaiqi redis-3.2.12]# cp sentinel.conf /root/myRedis-sentinel/s1.conf
[root@xinyeshuaiqi redis-3.2.12]# cp sentinel.conf /root/myRedis-sentinel/s2.conf
[root@xinyeshuaiqi redis-3.2.12]# cp sentinel.conf /root/myRedis-sentinel/s3.conf

哨兵配置文件需要改几个东西

（1）port 需要不同，我是依次设置成26379、26479、26579

# The port that this sentinel instance will run on
port 26379

（2）需要配置监控的master的ip

sentinel monitor mymaster 127.0.0.1 6381 2

（3）添加daemonize yes ，使哨兵后台运行

把s1.conf、s2.conf、s3.conf都修改完了，重头戏就来了

[root@xinyeshuaiqi myRedis-sentinel]# redis-sentinel s1.conf 
[root@xinyeshuaiqi myRedis-sentinel]# redis-sentinel s2.conf  
[root@xinyeshuaiqi myRedis-sentinel]# redis-sentinel s3.conf

启动哨兵集群

[root@xinyeshuaiqi myRedis-sentinel]# ps -ef |grep redis
root      8407     1  0 14:38 ?        00:00:01 redis-server *:6381
root      8730     1  0 14:44 ?        00:00:01 redis-server *:6382
root      8742     1  0 14:44 ?        00:00:01 redis-server *:6383
root     11390     1  0 15:36 ?        00:00:00 redis-sentinel *:26379 [sentinel]
root     11396     1  0 15:36 ?        00:00:00 redis-sentinel *:26479 [sentinel]
root     11400     1  0 15:36 ?        00:00:00 redis-sentinel *:26579 [sentinel]
root     11455  6728  0 15:37 pts/3    00:00:00 grep --color=auto redis

登陆sentinel 查看信息

[root@xinyeshuaiqi myRedis-sentinel]# redis-cli  -p 26379                  
127.0.0.1:26379> INFO sentinel
# Sentinel
sentinel_masters:1
sentinel_tilt:0
sentinel_running_scripts:0
sentinel_scripts_queue_length:0
sentinel_simulate_failure_flags:0
master0:name=mymaster,status=ok,address=127.0.0.1:6381,slaves=2,sentinels=3

看到哨兵的主为6381，有2slave

还能看到当前一共有3个哨兵

我们手动把master给干掉

[root@xinyeshuaiqi ~]# ps -ef | grep redis
root      8407     1  0 14:38 ?        00:00:02 redis-server *:6381
root      8730     1  0 14:44 ?        00:00:02 redis-server *:6382
root      8742     1  0 14:44 ?        00:00:02 redis-server *:6383
root     11390     1  0 15:36 ?        00:00:01 redis-sentinel *:26379 [sentinel]
root     11396     1  0 15:36 ?        00:00:01 redis-sentinel *:26479 [sentinel]
root     11400     1  0 15:36 ?        00:00:01 redis-sentinel *:26579 [sentinel]
root     12567 12547  0 15:59 pts/0    00:00:00 grep --color=auto redis
[root@xinyeshuaiqi ~]# 
[root@xinyeshuaiqi ~]# 
[root@xinyeshuaiqi ~]# kill -9 8407
[root@xinyeshuaiqi ~]# 
[root@xinyeshuaiqi ~]# 
[root@xinyeshuaiqi ~]# redis-cli -p 26379

看到6381的状态为down

过一会，6383成为主

刚才我忘设置一个东西就是哨兵的日志,在设置哨兵后台运行的同时设置日志的目录

daemonize yes

logfile /root/myRedis-sentinel/logs/sentinel1.log

就可以阻塞式的查看日志了，这里就不再演示了

[root@xinyeshuaiqi log]# redis-cli -p 6383
127.0.0.1:6383> 
127.0.0.1:6383> 
127.0.0.1:6383> set k2 nima
OK
127.0.0.1:6383> get k2
"nima"
127.0.0.1:6383> info replication
# Replication
role:master
connected_slaves:1
slave0:ip=127.0.0.1,port=6382,state=online,offset=91286,lag=0
master_repl_offset:91286
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:91285

测试一下发现6383已经有写能力

已经成为主且有一个从 6382

我们尝试连接下曾经的主

[root@xinyeshuaiqi log]# redis-cli -p 6381
Could not connect to Redis at 127.0.0.1:6381: Connection refused
Could not connect to Redis at 127.0.0.1:6381: Connection refused
not connected>

连不上哇

我们再来思考一个问题，如果我们现在把曾经的老大复活，他还能成为老大吗？？？

就像电影黑社会的老大进监狱了，小弟成老大了，老大出狱了，不愿意让位了。。。

redis中是怎木样的呢？我也不知道，试一波

127.0.0.1:6381> info replication
# Replication
role:slave
master_host:127.0.0.1
master_port:6383
master_link_status:up
master_last_io_seconds_ago:0
master_sync_in_progress:0
slave_repl_offset:154533
slave_priority:100
slave_read_only:1
connected_slaves:0
master_repl_offset:0
repl_backlog_active:0
repl_backlog_size:1048576
repl_backlog_first_byte_offset:0
repl_backlog_histlen:0

127.0.0.1:6381> set k3 nanshou
(error) READONLY You can't write against a read only slave.

扎心了，曾经的老大已经成小弟了。。。

[root@xinyeshuaiqi log]# redis-cli -p 6383
127.0.0.1:6383> info replication
# Replication
role:master
connected_slaves:2
slave0:ip=127.0.0.1,port=6382,state=online,offset=171417,lag=0
slave1:ip=127.0.0.1,port=6381,state=online,offset=171284,lag=0
master_repl_offset:171417
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:2
repl_backlog_histlen:171416

对于现任老大而言，我马上就知道曾经的老大成了我的小弟

关于主从集群和哨兵相关介绍就到这里，下一篇准备好好整理下redis分布式集群

操作过程中遇到任何问题可以联系我

转载请注明：汪明鑫的个人博客 » 一步步搭建Redis主从集群和哨兵集群