Install Ruby with Ansible

20 Mar 2017

Install and configure Ansible

I’m using OSX so brewis the best way to install Ansible. Please refer to documentation to find out how to install it in your system.

You will need to have ssh access to a linux machine, so that Ansible can login to it and run instructions from a playbook. It doesn’t need to have a client installed on the machine, since it just uses bash to run the commands. In my case it will be an Ubuntu server with IP address 36.137.17.20.

$ brew install ansible
$ echo '36.137.17.20 ansible_user=ubuntu' >> /usr/local/etc/ansible/hosts

Let’s check how installation works by updating the remote system:

$ ansible all -a "apt-get update" --become
36.137.17.20 | SUCCESS | rc=0 >>
Hit:1 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial InRelease
Get:2 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial-updates InRelease [102 kB]
Get:3 http://eu-central-1.ec2.archive.ubuntu.com/ubuntu xenial-backports InRelease [102 kB]
Get:4 http://security.ubuntu.com/ubuntu xenial-security InRelease [102 kB]
Fetched 306 kB in 0s (1216 kB/s)
Reading package lists...

Playbook to install Ruby

Ansible uses Yaml to describe steps it is going to execute remotely. For this article I prepared a playbook install-ruby.yml. And below I will describe it in details.

First thing that we would like to do is to check if ruby already installed:

---
- name: Install Ruby 2.3.3
  hosts: all
  remote_user: ubuntu
  become: yes
  tasks:
    - name: Check if Ruby is installed
      command: which ruby
      register: ruby_check
      ignore_errors: yes

So, we tell Ansible to login to all hosts we have, use remote user ubuntu and become root via sudo. Then we register a new task that runs one single command which ruby. Result of this command will be either 0, if everything is ok, or an error code.

Next there is a block of steps that will download, unpack, and compile Ruby, and it makes sense to run this block only if Ruby is not installed (return code of ruby_check is not 0):

- block:
  - name: Update the system
    apt: update_cache=true
...
  when: ruby_check.rc != 0

And that’s pretty much it. Other parts of the main block are self descriptive and as I said they will just download, unpack, compile Ruby and install it in the system. Check the script to find out how these steps work.

$ ansible-playbook install-ruby.yml