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

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:6.2
slave:
  image: redis:6.2
  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            

Execute 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)