redis_cluster_sample

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][1]

Prerequisite

Install [Docker][4] and [Docker Compose][3] in testing environment

If you are using Windows, please execute the following command before "git clone" to disable changing the line endings of script files into DOS format

git config --global core.autocrlf false

Docker Compose template of Redis cluster

The template 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 and Scale out the instance number of slaves

docker-compose up -d --scale slave=2 --scale sentinel=3

Check the status of redis cluster

docker-compose ps

The result is

          Name                        Command               State          Ports       
---------------------------------------------------------------------------------------
redis_cluster_master_1     docker-entrypoint.sh redis ...   Up      6379/tcp           
redis_cluster_sentinel_1   sentinel-entrypoint.sh           Up      26379/tcp, 6379/tcp
redis_cluster_sentinel_2   sentinel-entrypoint.sh           Up      26379/tcp, 6379/tcp
redis_cluster_sentinel_3   sentinel-entrypoint.sh           Up      26379/tcp, 6379/tcp
redis_cluster_slave_1      docker-entrypoint.sh redis ...   Up      6379/tcp           
redis_cluster_slave_2      docker-entrypoint.sh redis ...   Up      6379/tcp           

Execute the test scripts

./my_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 redis_cluster_master_1
docker unpause redis_cluster_master_1

And get the sentinel infomation with following commands

docker exec redis_cluster_sentinel_1 redis-cli -p 26379 SENTINEL get-master-addr-by-name mymaster