Docker Drupal Redis Sentinel

Installing and running “redis” seem to be enough to run Drupal with it - but sometimes you want to scale Redis for HA.

Tool named “redis-sentinel” provides “redis” services such as:

• Monitoring: It can check master or slave services whether is working correctly and healthy or not.
• Notification: It can notify when a service goes down.
• Automatic Failover: It starts a failover scenario and assigns one of slaves as a master when master service goes down.
• Configuration Provider: It can configure and share master service information when a new service is added to cluster.

What do I get with this Repo?

Following services are created using Docker:

• Redis master: Master Redis Server
• Redis slave: Slave Redis Server
• Redis sentinel: Sentinel Server
• Nginx: For Drupal
• PHP: PHP FPM for Drupal
• MySQL: For Drupal DB

Setup Drupal + Redis + Sentinels locally

Get this repo

git clone {this_repo}

Get Drupal

Composer install Drupal

Composer install Drupal into subdir called drupal.

composer create-project drupal-composer/drupal-project:8.x-dev drupal --no-interaction

Drupal Config

See README-DRUPAL.md

Run all services locally

Get it up

docker-compose up --build -d
....
....
....

Scale up Redis slaves & Sentinels

docker-compose scale slave=2 sentinel=3
....
....
....
Creating docker_redis_sentinel_slave_2 ... done
Starting docker_redis_sentinel_sentinel_1 ... done
Creating docker_redis_sentinel_sentinel_2 ... done
Creating docker_redis_sentinel_sentinel_3 ... done

Is it up?

docker-compose ps
              Name                            Command               State           Ports
--------------------------------------------------------------------------------------------------
docker_redis_sentinel_db_1         docker-entrypoint.sh mysqld      Up      0.0.0.0:3306->3306/tcp
docker_redis_sentinel_master_1     docker-entrypoint.sh redis ...   Up      6379/tcp
docker_redis_sentinel_php_1        docker-php-entrypoint php-fpm    Up      9000/tcp
docker_redis_sentinel_sentinel_1   entrypoint.sh                    Up      6379/tcp
docker_redis_sentinel_sentinel_2   entrypoint.sh                    Up      6379/tcp
docker_redis_sentinel_sentinel_3   entrypoint.sh                    Up      6379/tcp
docker_redis_sentinel_slave_1      docker-entrypoint.sh redis ...   Up      6379/tcp
docker_redis_sentinel_slave_2      docker-entrypoint.sh redis ...   Up      6379/tcp
docker_redis_sentinel_web_1        nginx -g daemon off;             Up      0.0.0.0:80->80/tcp

References:

https://medium.com/@mustafa.ileri/redis-clustering-with-redis-sentinel-on-docker-1090ab876f97 https://medium.com/@amila922/redis-sentinel-high-availability-everything-you-need-to-know-from-dev-to-prod-complete-guide-deb198e70ea6