Hello Ansible

Ansible is an automation tool for managing the state of a system.¹ Ansible playbooks can target remote or local systems. I mainly use ansible playbooks to provision linux virtual machines.

Prerequisites:

Ubuntu 20.04 with Python3 installed.

Part 1: Installation

More details can be found in the official Ansible documentation², these are the steps I took on a fresh Ubuntu virtual machine.

Check python3 and pip installation

$ which python3
/usr/bin/python3
$ python3 -m pip -V
pip 22.0.2 from /usr/lib/python3/dist-packages/pip (python 3.10)

Install ansible via pip.

$ python3 -m pip install --user ansible
$ ansible --version
ansible [core 2.14.3]

Install Python and Pip

If needed install python3 and pip, process will be different depending on things, ymmv but this womm

$ apt-get update -y
$ apt-get install python3
$ apt-get install python3-pip

Part 2: Use a Playbook

Create project directory and set location for ansible config file. Probably not strictly necessary because ansible checks the current directory for a config anyway.

$ mkdir hello-ansible
$ cd hello-ansible
$ export ANSIBLE_CONFIG=~/hello-ansible/ansible.cfg

Define ansible configuration variables in a config file. In this case we’re going to run this playbook on the target machine, so we can ignore the warning from ansible about using the “implicit localhost”.

~/hello-ansible/ansible.cfg

[defaults]
localhost_warning=false

Place the following in a new file named playbook.yml³

~/hello-ansible/playbook.yml

---
- name: Hello World playbook
  hosts: localhost
  tasks:
    - name: Hello World  - debug
      ansible.builtin.debug:
        msg:
          - "Hello World"

Run the playbook.

$ ansible-playbook playbook.yml

PLAY [Hello World playbook] ****************************************************

TASK [Gathering Facts] *********************************************************
ok: [localhost]

TASK [Hello World  - debug] ****************************************************
ok: [localhost] => {
    "msg": [
        "Hello World"
    ]
}

PLAY RECAP *********************************************************************
localhost                  : ok=2    changed=0    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0

Part 3: Use a Role

We can refactor our playbook into a role⁴. Roles are useful if we wanted to reuse this set of tasks in different playbooks, or with use a set of tasks with different input variable values.

$ mkdir -p ~/hello-ansible/roles/hello/tasks

~/hello-ansible/roles/hello/tasks/main.yml

---
- name: Hello World  - role
  ansible.builtin.debug:
    msg:
      - "Hello World"

~/hello-ansible/playbook.yml

---
- name: Hello World playbook
  hosts: localhost
  roles:
    - hello

Our directory structure should look like this now.

├── playbook.yml
└── roles
    └── hello
        └── tasks
            └── main.yml

Running ansible-playbook playbook.yml should give the same output as above.

Wrapping up

At this point the hello-ansible directory contains a working playbook. Building on from here we can add tasks and roles to accomplish all sorts of things.