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Short Description
HA Redis Cluster with Sentinel
Full Description

redis-cluster

Redis cluster with Docker Compose

Using Docker Compose to setup a redis cluster with sentinel.

This project is inspired by the project of https://github.com/mdevilliers/docker-rediscluster

Prerequisite

Install Docker and Docker Compose in testing environment

Docker Compose template of Redis cluster

The tempalte defines the topology of the Redis cluster

master:
  image: redis:3
slave:
  image: redis:3
  command: redis-server --slaveof redis-master 6379
  links:
    - master:redis-master
sentinel:
  build: sentinel
  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/

License

Apache 2.0 license

Contributors

Docker Pull Command
Owner
erichsu
Source Repository

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