The Request Metrics application will use Redis as its main data store. We need to install Redis on our servers to find out if this is a good plan. Ansible provides a repeatable way of doing this configuration work.

Redis setup takes more steps than just apt-get install redis. Because we really don’t want to learn all the necessary steps, we turn to pre-built role written by David Wittman.

Download Redis Roles With Galaxy

Redis roles are shared through Ansible Galaxy. The davidwittman.redis role is downloaded by running Galaxy from the CLI:

> ansible-galaxy install davidwittman.redis

There is one problem with the above command: it downloads the role to a system wide, shared location. Each developer needs to run the above command before running the playbook. We like our repositories to be standalone when possible. A slightly modified command saves the role locally. This lets us commit it to git:

> ansible-galaxy install davidwittman.redis -p ./roles

Install Redis

Now that the role is downloaded, it can be called from our playbook. The include_role module works well because it packages everything up into a single, self contained task:

- hosts: redisHosts

    # Install Redis Using davidwittman.redis Role
    - name: Install single node redis # We will want master/slave or clustering in production
        redis_version: 5.0.7          # We want new Redis hotness
        redis_port: 6379              # 6379 is the default port, but we like to be explicit
        redis_bind:         # Tells Redis to only accept requests from localhost
      include_role: name=davidwittman.redis

And we’re done! A bunch of time was saved by using an Ansible Galaxy role written by a stranger on the internet. Next, we’ll code up the Request Metrics application to connect to our fresh Redis instance.