redis-sentinel on local

Redis cluster with Docker Compose

The difference from https://github.com/AliyunContainerService/redis-cluster is that

1. the master and slave are all protected redis nodes.
2. using ARG for docker-composer (version2) and Dockerfile to pass the passwords into the docker images related files, such sd Dockerfile, entrypoint.sh etc. Now all the parameters to tweak all in docker-compose.yml.

Docker Compose template of Redis cluster

The tempalte defines the topology of the Redis cluster

version: '2'

services:
  master:
    image: redis:3
    command: redis-server --requirepass 12345678 --masterauth 12345678
  slave:
    image: redis:3
    command: redis-server --requirepass 12345678 --masterauth 12345678
    links:
      - master:redis-master
  sentinel:
    build: 
      context: sentinel
      args: 
        - PW=12345678
        - QUORUM=1
    environment:
      - SENTINEL_DOWN_AFTER=5000
      - SENTINEL_FAILOVER=5000
    links:
      - master:redis-master
      - slave

There are following services in the cluster,

• master: Redis master
• slave: Redis slave
• sentinel: Redis sentinel

The sentinels are configured with a "mymaster" instance with the following properties -

sentinel monitor mymaster redis-master 6379 2
sentinel down-after-milliseconds mymaster 5000
sentinel parallel-syncs mymaster 1
sentinel failover-timeout mymaster 5000

The details could be found in sentinel/sentinel.conf

The default values of the environment variables for Sentinel are as following

• SENTINEL_QUORUM: 2
• SENTINEL_DOWN_AFTER: 30000
• SENTINEL_FAILOVER: 180000

Play with it

Build the sentinel Docker image

docker-compose build

Start the redis cluster

docker-compose up -d

Check the status of redis cluster

docker-compose ps

The result is

         Name                        Command               State          Ports        
--------------------------------------------------------------------------------------
rediscluster_master_1     docker-entrypoint.sh redis ...   Up      6379/tcp            
rediscluster_sentinel_1   docker-entrypoint.sh redis ...   Up      26379/tcp, 6379/tcp 
rediscluster_slave_1      docker-entrypoint.sh redis ...   Up      6379/tcp     

Scale out the instance number of sentinel

docker-compose scale sentinel=3

Scale out the instance number of slaves

docker-compose scale slave=2

Check the status of redis cluster

docker-compose ps

The result is

         Name                        Command               State          Ports        
--------------------------------------------------------------------------------------
rediscluster_master_1     docker-entrypoint.sh redis ...   Up      6379/tcp            
rediscluster_sentinel_1   docker-entrypoint.sh redis ...   Up      26379/tcp, 6379/tcp 
rediscluster_sentinel_2   docker-entrypoint.sh redis ...   Up      26379/tcp, 6379/tcp 
rediscluster_sentinel_3   docker-entrypoint.sh redis ...   Up      26379/tcp, 6379/tcp 
rediscluster_slave_1      docker-entrypoint.sh redis ...   Up      6379/tcp            
rediscluster_slave_2      docker-entrypoint.sh redis ...   Up      6379/tcp            

Execut the test scripts

./test.sh

to simulate stop and recover the Redis master. And you will see the master is switched to slave automatically.

Or, you can do the test manually to pause/unpause redis server through

docker pause rediscluster_master_1
docker unpause rediscluster_master_1

And get the sentinel infomation with following commands

docker exec rediscluster_sentinel_1 redis-cli -p 26379 SENTINEL get-master-addr-by-name mymaster

References

https://github.com/mdevilliers/docker-rediscluster

[https://registry.hub.docker.com/u/joshula/redis-sentinel/] 2

License

Apache 2.0 license

Contributors

• Li Yi (denverdino@gmail.com)
• Ty Alexander (ty.alexander@gmail.com)