Using Ansible with Vagrant to create a Docker host

To step through this recipe, you will need the following:

Because writing complex Ansible playbooks is out of the scope of this book, we'll use a very simple one, so you can learn more about Ansible later and still reuse this recipe.

---
- hosts: all
  become: yes
  tasks:
    - name: Enable EPEL
      yum: name=epel-release state=present
    - name: Create a Docker group
      group: name=docker state=present
    - name: Add the vagrant user to Docker group
      user: name=vagrant groups=docker append=yes
    - name: Install Docker
      yum: name=docker state=present
    - name: Enable and Start Docker Daemon
      service: name=docker state=started enabled=yes

Vagrant.configure("2") do |config|
  config.vm.box = "bento/centos-7.2"
  config.vm.define "srv-1" do |config|
    config.vm.hostname = "srv-1"
    config.vm.network "private_network", type: "dhcp"
  end
end

    config.vm.provision "ansible" do |ansible|
      ansible.playbook = "playbook.yml"
    end

$ vagrant ssh
[vagrant@srv-1 ~]$ systemctl status docker
[vagrant@srv-1 ~]$ docker --version
Docker version 1.10.3, build d381c64-unsupported
[vagrant@srv-1 ~]$ docker run -it --rm alpine /bin/hostname
0f44a4d7afcd

What if for some reason you don't or can't have Ansible installed on your host machine? Alternatively, maybe you need a specific Ansible version on your Vagrant box to mimic production and you don't want to mess with your local Ansible installation. There's an interesting variant Ansible provider you can use: it will either use Ansible directly from the guest VM, and if it's not installed, it will install it from official repositories or PIP. You can use this very simple default configuration:

    config.vm.provision "ansible_local" do |ansible|
      ansible.playbook = "playbook.yml"
    end

You can also use the following command:

$ vagrant up
[…]
==> srv-1: Running provisioner: ansible_local...
    srv-1: Installing Ansible...
    srv-1: Running ansible-playbook...
[…]

Log in to the box via SSH and check that Ansible is locally installed with the latest version:

$ vagrant ssh
$ ansible --version
ansible 2.1.1.0

If your use case is different, you can use more precise deployment options, to be able to fix an Ansible version number using PIP (here, version 1.9.6 instead of the latest 2.x series):

    config.vm.provision "ansible_local" do |ansible|
      ansible.version = "1.9.6"
      ansible.install_mode = :pip
      ansible.playbook = "playbook.yml"
    end

You can also use the following command:

$ vagrant up
[…]
==> srv-1: Running provisioner: ansible_local...
    srv-1: Installing Ansible...
    srv-1: Installing pip... (for Ansible installation)
    srv-1: Running ansible-playbook...

Inside the Vagrant guest, you can now check for the PIP and Ansible versions:

$ pip --version
pip 8.1.2 from /usr/lib/python2.7/site-packages (python 2.7)
$ ansible --version
ansible 1.9.6

You can also check if our playbook has been installed correctly with the old 1.x Ansible version:

$ docker version

Also check if Docker is installed, and verify now it's working as the Vagrant user:

$ docker run -it --rm alpine ping -c2 google.com
PING google.com (216.58.211.78): 56 data bytes
64 bytes from 216.58.211.78: seq=0 ttl=61 time=22.078 ms
64 bytes from 216.58.211.78: seq=1 ttl=61 time=21.061 ms