In the last article I introduced how to install and use redis sentinel. As I’m using ruby, I need to use this new redis configuration with ruby (on rails).

For ruby on rails use redis-sentinel gem.

Then your redis initializer will look like

sentinels = [
  { host: '10.0.0.1', port: 17700 },
  { host: '10.0.0.2', port: 17700 },
  { host: '10.0.0.3', port: 17700 },
  { host: '10.0.0.4', port: 17700 }
]
# redis master name from sentinel.conf is 'master'
Redis.current = Redis.new(master_name: 'master', sentinels: sentinels)

You can use your redis then as usual.

When using sidekiq, configuration is pretty simple too

require 'sidekiq/web'
require 'redis-sentinel'
require 'sidetiq/web'

rails_root = ENV['RAILS_ROOT'] || File.dirname(__FILE__) + '/../..'
rails_env = ENV['RAILS_ENV'] || 'development'

sentinels = [
  { host: '10.0.0.1', port: 17700 },
  { host: '10.0.0.2', port: 17700 },
  { host: '10.0.0.3', port: 17700 },
  { host: '10.0.0.4', port: 17700 }
]

redis_conn = proc { 
  Redis.current = Redis.new(master_name: 'master', sentinels: sentinels) 
}
redis = ConnectionPool.new(size: 10, &redis_conn)

Sidekiq.configure_server do |config|
  config.redis = redis
end

Sidekiq.configure_client do |config|
  config.redis = redis
end

You can test your configuration. Run rails console and test with

Loading production environment (Rails 3.2.16)
1.9.3p448 :001 > Redis.current.keys("*").count
 => 746
1.9.3p448 :002 > Redis.current
 => #<Redis client v3.0.5 for redis://10.0.0.2:6379/0>

if you see “127.0.0.1:6379”, something is probably wrong. Then try to set/get some key and check Redis.current once again.