Adds the Redis Sentinel recipe

[radamanthus]

Description of your patch

Adds the redis-sentinel recipe

Recommended Release Notes

Adds the redis-sentinel recipe to support high-availability redis configurations

Estimated risk

Low

Components involved

redis-sentinel custom chef recipe

Description of testing done

See QA instructions

QA Instructions

Boot a cluster environment for the rails_activejob_example application

• Unicorn
• Ruby 2.3
• Rubygems 2.6.3
• Postgres 9.4
• any region

The cluster should have the following instances:

• 1 app_master
• 1 app
• 1 redis
• 1 sidekiq
• 1 db_master

Enable both the redis and the redis-sentinel recipes. After enabling both recipes and running chef, run monit summary on the app instances and the sidekiq instance. All of them should have redis-sentinel running.