Detailed explanation of the master-slave configuration tutorial of redis under Docker

docker run --name redis-6379 -p 6379:6379 -d redis
docker run --name redis-6380 -p 6380:6379 -d redis
docker run --name redis-6381 -p 6381:6379 -dredis

[tcy@tcy1 ~]$ docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
a9fa77adc598 daocloud.io/library/redis "docker-entrypoint.s 2 hours ago Up 2 hours 0.0.0.0:6381->6379/tcp redis-6381   
6ee2f2f007e6 daocloud.io/library/redis "docker-entrypoint.s 2 hours ago Up 2 hours 0.0.0.0:6380->6379/tcp redis-6380   
ab54741166e1 daocloud.io/library/redis "docker-entrypoint.s 3 hours ago Up 3 hours 0.0.0.0:6379->6379/tcp redis-6379

docker exec -it ab54741166e1 redis-cli: Enter the container [root@tcy1 tcy]# docker exec -it ab54741166e1 redis-cli
127.0.0.1:6379> set b tcy
OK
127.0.0.1:6379> get b
"tcy"
127.0.0.1:6379> quit[root@tcy1 tcy]#

redis-6379: 172.17.0.1:6379
redis-6380: 172.17.0.2:6379
redis-6381:172.17.0.3:6379

[root@tcy1 tcy]# docker exec -it ab54741166e1 /bin/bash
root@ab54741166e1:/data# redis-cli
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:0
master_replid:d43d1ae8cde6cb084220e18b926aba79e0bb2504
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
127.0.0.1:6379> quit
root@ab54741166e1:/data# exit 
exit

[root@tcy1 tcy]# docker exec -it a9fa77adc598 /bin/bash //redis-6380
root@a9fa77adc598:/data# redis-cli
127.0.0.1:6379> SLAVEOF 172.17.0.1 6379
OK
127.0.0.1:6379> quit
root@a9fa77adc598:/data# exit
exit
[root@tcy1 tcy]# docker exec -it 6ee2f2f007e6 /bin/bash //redis-6381
root@6ee2f2f007e6:/data# redis-cli
127.0.0.1:6379> SLAVEOF 172.17.0.1 6379
OK
127.0.0.1:6379> quit

[root@tcy1 tcy]# docker exec -it ab54741166e1 /bin/bash
root@ab54741166e1:/data# redis-cli
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:2
slave0:ip=172.17.0.3,port=6379,state=online,offset=378,lag=1
slave1:ip=172.17.0.2,port=6379,state=online,offset=378,lag=0
master_replid:ce193b15cfd57f7dc3ccfbf2a4aef6156b131e6d
master_replid2:0000000000000000000000000000000000000000
master_repl_offset:378
second_repl_offset:-1
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:1
repl_backlog_histlen:378
127.0.0.1:6379> quit
root@ab54741166e1:/data# exit
exit

[root@tcy1 tcy]# docker exec -it a9fa77adc598 /bin/bash
root@a9fa77adc598:/data# cd / && touch sentinel.conf 
root@a9fa77adc598:/# vim /sentinel.conf

root@a9fa77adc598:/# redis-sentinel /sentinel.conf
342:X 24 Jun 11:37:58.934 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo
342:X 24 Jun 11:37:58.957 # Redis version=4.0.10, bits=64, commit=00000000, modified=0, pid=342, just started
342:X 24 Jun 11:37:58.958 # Configuration loaded
342:X 24 Jun 11:37:58.959 # You requested maxclients of 10000 requiring at least 10032 max file descriptors.
342:X 24 Jun 11:37:58.959 # Server can't set maximum open files to 10032 because of OS error: Operation not permitted.
342:X 24 Jun 11:37:58.960 # Current maximum open files is 4096. maxclients has been reduced to 4064 to compensate for low ulimit. If you need higher maxclients increase 'ulimit -n'.
        _._                         
      _.-``__ ''-._                       
   _.-`` `. `_. ''-._ Redis 4.0.10 (00000000/0) 64 bit
 .-`` .-```. ```\/ _.,_ ''-._                  
 ( ' , .-` | `, ) Running in sentinel mode
 |`-._`-...-` __...-.``-._|'` _.-'| Port: 26379
 | `-._ `._ / _.-' | PID: 342
 `-._ `-._ `-./ _.-' _.-'                  
 |`-._`-._ `-.__.-' _.-'_.-'|                 
 | `-._`-._ _.-'_.-' | http://redis.io    
 `-._ `-._`-.__.-'_.-' _.-'                  
 |`-._`-._ `-.__.-' _.-'_.-'|                 
 | `-._`-._ _.-'_.-' |                 
 `-._ `-._`-.__.-'_.-' _.-'                  
   `-._ `-.__.-' _.-'                    
     `-._ _.-'                      
       `-.__.-'                        
 
342:X 24 Jun 11:37:59.068 # WARNING: The TCP backlog setting of 511 cannot be enforced because /proc/sys/net/core/somaxconn is set to the lower value of 128.
342:X 24 Jun 11:37:59.089 # Sentinel ID is dfd5a5bfe1036b1df3395c4ba858329034fc5b7e
342:X 24 Jun 11:37:59.091 # +monitor master mymaster 172.17.0.1 6379 quorum 1
342:X 24 Jun 11:37:59.110 * +slave slave 172.17.0.3:6379 172.17.0.3 6379 @ mymaster 172.17.0.1 6379
342:X 24 Jun 11:37:59.115 * +slave slave 172.17.0.2:6379 172.17.0.2 6379 @ mymaster 172.17.0.1 6379
 
342:X 24 Jun 11:39:27.601 * +sentinel sentinel ba9b0d0539d8273edfcbd922fe138f50daa78bbb 172.17.0.2 26379 @ mymaster 172.17.0.1 6379
342:X 24 Jun 11:41:59.144 * +sentinel sentinel f0510f8582b72c056531f219397ed8826683e665 172.17.0.1 26379 @ mymaster 172.17.0.1 6379

[tcy@tcy1 ~]$ docker stop ab54741166e1
ab54741166e1

[root@tcy1 /]# docker exec -it 6ee2f2f007e6 /bin/bash
root@6ee2f2f007e6:/data# redis-cli
127.0.0.1:6379> info replication
# Replication
role:master
connected_slaves:1
slave0:ip=172.17.0.3,port=6379,state=online,offset=66906,lag=1
master_replid:5a7489c8181ddf0d73d418d30d6a4c8e039198ba
master_replid2:ce193b15cfd57f7dc3ccfbf2a4aef6156b131e6d
master_repl_offset:67041
second_repl_offset:65534
repl_backlog_active:1
repl_backlog_size:1048576
repl_backlog_first_byte_offset:85
repl_backlog_histlen:66957
127.0.0.1:6379>