Redis-cluster-docker-cheatsheet

This project will help your learn how to establish redis-cluster by shell and docker compose.

Architecture

redis-cluster-docker-cheatsheat
├── README.md
├── master-slave       
│   └── docker-compose.yml
├── master-slave-sentinel
│   ├── docker-compose.yml
│   └── sentinel
│       └── sentinel.conf
└── redis-cluster
    ├── docker-compose.yml
    ├── needToRun.sh
    └── redis-cluster.tmpl

Quickstart

1. Clone the repository.

$ mkdir redis-cluster && cd redis-cluster
$ git clone https://github.com/ChickenBenny/redis-cluster-sentinel-docker

2. Choose the structure you want to build, and use docker compose in the folder to build the database.

Master-slave => It contain one master and two slave example. If you want to build the sturcture with more slave, take a look at the master-slave chapter.

Master-slave-sentinel => It contain one master and two slave structure with three sentinels example. If you want to build the sturcture with more slaves or sentinels, take a look at the master-slave-sentinel chapter.

Redis-cluster => It contain three master slave sturcture example. If you want to build the cluster with more master slave structure, take a look at the redis cluster chapter.

Setting cheatsheet

1. Master-slave

The stucture need one master and N slaves, remember the slave container youe need to add --slaveof ${name of master container} ${master expose port}.

Check the structure

1. Check whether all the container is built.

$ docker ps

2. Enter redis-master container and check the replications status. The role should be 'master' and the connect slave should be '2'.

$ docker exec -it redis-master sh      // Enter the container
$ redis-cli                            // Connect the redis server
127.0.0.1:6379> info replication       

3. Enter redis-slave container and check the replications status. The role should be 'slave' and the master host should be ${redis-master container name}.

2. Master-slave with sentinel

If you want to add sentinel in your master slave structure, you need to add sentinel folder and setting the config first.

• sentinel config

port 5000
sentinel monitor mymaster redis-master 6379 2
sentinel down-after-milliseconds mymaster 5000
sentinel failover-timeout mymaster 60000
sentinel parallel-syncs mymaster 1

1. portThe sentinel runs on which port in the container.
2. sentinel monitor <master-group-name> <ip> <port> <quorum> The quorum is the number of Sentinels that need to agree about the fact the master is not reachable, and eventually start a failover procedure. The quorum is only used to detect the failure!!
3. sentinel <option_name> <master_name> <option_value> down-after-milliseconds is the time in milliseconds an instance should not be reachable. parallel-syncs sets the number of replicas that can be reconfigured to use the new master after a failover at the same time.

Check the structure

1. Check whether sentinels is built and check the monitoring information.

$ docker exec -it redis-sentinel1 sh
$ redis-cli -p 5000
127.0.0.1:5000 > info sentinel

2. Try to stop the master container and check whether sentinel switch the new master.

$ docker stop redis-master

3. Go to the slave container and check the role and replication information. One of the slave should be change to master, and the connect slave should be 1.

3. Redis-cluster

• Shell Important : you should find your ip first and type in the shell script. If you want to build more db, you can change {7001..${7001 + N you wanted}}.

#!/bin/bash
ip=${your ip}
for port in {7001..7006}; 
do 
mkdir -p ./${port}/conf && PORT=${port} IP=${ip} envsubst < ./redis-cluster.tmpl > ./${port}/conf/redis.conf; 
done

• Redis-cluster.tmpl

port ${PORT} 
protected-mode no 
cluster-enabled yes 
cluster-config-file nodes.conf 
cluster-node-timeout 5000 
cluster-announce-ip ${IP}
cluster-announce-port ${PORT} 
cluster-announce-bus-port 1${PORT} 
appendonly yes

• docker compose The cluster creat command I wrote in redis-1 and you can use docker-compose up to build the cluster.

$ export IP=${your ip}
$ docker-compose up

Check the structure

1. Check the docker compose log information, whether the cluster is connect successfully.

2. Go to redis-1 container and check the cluster info, the cluster status should be 'OK' and the cluster size should be 3.

$ docker exec -it redis-1 sh
$ redis-cli -p 7001 -c            
127.0.0.1:7001> cluster info

3. You can also go to other container to connect the cluster.

redis-cli -p ${container ip} -c

Learn more

If you want to learn more about redis, check out my medium article.

• Redis introduction : https://blog.devops.dev/redis-introduction-from-zero-to-hero-part-i-7c13e63170f5
• Redis persistence and cap theorem : https://blog.devops.dev/redis-persistence-and-cap-theorem-from-zero-to-hero-part-ii-91eaedf58d79
• Redis structure with docker : https://blog.devops.dev/redis-cluster-and-sentinel-with-docker-from-zero-to-hero-part-iv-63ba9d196cc3