Ansible: Introduction to Playbooks

What is a Playbook

A Playbook in ansible is a file containing a set of instructions for automating systems configuration. It like a bash script but in ansible "language". A ad-hoc command is suitable for a basic single line task. But if we want to perform a complex and repeatable deployement, we certainly must use a playbook.

Playbooks are written in YAML following a structured syntax. A playbook contains an ordered list of plays that runs in order from top to bottom by default.

---
- name: Update servers
  hosts: servers
  remote_user: ans-user

  tasks:
  - name: Update nginx
    ansible.builtin.dnf:
      name: nginx
      state: latest

To ping all hosts;

---
- name: Ping all hosts
  hosts: servers

  tasks:
  - name: Ping servers
    ansible.builtin.ping:

This is how you run a playbook:

ansible-playbook my_playbook.yml

or in dry run mode:

ansible-playbook --check my_playbook.yml

or to check the syntax of our playbook:

ansible-playbook --syntax-check my_playbook.yml

or to list all hosts:

ansible-playbook --list-hosts my_playbook.yml

or to list all tasks:

ansible-playbook --list-tasks my_playbook.yml

We can a lot more configuration to the playbook to perform advanced automation tasks. We are going to leave that for a future post.

By default, ansible gather facts about the nodes before executing the playbook To disable this feature, we can add gather_facts: false to our playbook:

---
- name: Ping all hosts
  hosts: servers
  gather_facts: false

  tasks:
  - name: Ping servers
    ansible.builtin.ping:

Example of Simple Playbooks

Ping hosts

We've already seen how to do that. This is a simple way to ping nodes using ansible playbook:

---
- name: Ping Linux hosts
  hosts: servers
  gather_facts: false

  tasks:
  - name: Ping servers
    ansible.builtin.ping:

Install/Uninstall packages

---
- name: Install/uninstall packages
  hosts: servers
  become: 'yes'

  tasks:
  - name: Install OpenSSH on Linux servers
    ansible.builtin.dnf:
      name: openssh
      state: present

  - name: Uninstall Apache
    ansible.builtin.dnf:
      name: httpd
      state: absent

Update packages

---
- name: Update packages
  hosts: servers
  become: 'yes'

  tasks:
  - name: Update OpenSSH on Linux servers
    ansible.builtin.dnf:
      name: openssh
      state: latest

  - name: Uninstall Apache
    ansible.builtin.dnf:
      name: nginx
      state: latest

Enable/Disable services

---
- name: Enable nginx service
  hosts: servers
  become: 'yes'

  tasks:
  - name: Install nginx
    ansible.builtin.service:
      name: nginx
      state: present

  - name: Enable nginx service
    ansible.builtin.service:
      name: nginx
      state: started
      enabled: yes

  - name: Disable Apache service
    ansible.builtin.service:
      name: cups
      state: stopped
      enabled: no