ha-redis

Redis high availability with Docker Compose

Using Docker Compose to setup an with sentinel.

Prerequisite

Install Docker and Docker Compose in testing environment

Docker Compose template of Redis cluster

There are following services in the cluster,

• master: Redis master
• slave: Redis slave
• sentinel: Redis sentinel
• proxy: The load balancing proxy

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 and load balancing proxy Docker images

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        
--------------------------------------------------------------------------------------
haredis_master_1     docker-entrypoint.sh redis ...   Up      6379/tcp                                       
haredis_proxy_1      /haproxy-entrypoint.sh hap ...   Up      0.0.0.0:6379->6379/tcp, 0.0.0.0:9000->9000/tcp 
haredis_sentinel_1   sentinel-entrypoint.sh           Up      26379/tcp, 6379/tcp                            
haredis_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

You can do the test manually to pause/unpause redis server through

docker-compose pause master
docker-compose unpause master

And get the sentinel infomation with following commands

docker-compose exec sentinel redis-cli -p 26379 info Sentinel
docker-compose exec sentinel redis-cli -p 26379 SENTINEL get-master-addr-by-name mymaster