Chapter #20: How to Create Ansible Plays and Playbooks

In this chapter, we will explain how to create Ansible Plays and Playbooks using Ansible modules.

Ansible ships with standalone scripts called modules that are used in playbooks for the execution of specialized tasks on remote nodes.

Modules come in handy for automating tasks such as package management, archiving, and copying files, to mention just a few. They allow you to make tweaks on configuration files and manage devices such as routers, switches, load balancers, firewalls, and a host of other devices.

The objective of this subtopic is to give you an overview of various tasks that can be accomplished by Ansible modules:

Package Management in Linux

Package management is one of the most essential and frequent tasks carried out by systems administrators. Ansible ships with modules that help you execute package management tasks both in RedHat and Debian-based systems.

They are relatively easy to guess. There is the apt module for APT package management for Debian-based systems, the old yum module for YUM package management, and the dnf module associated with newer RHEL distributions.

Below are a few examples of how the modules can be used in a playbook:

Example 1: Installing the Apache Web Server on RHEL

This playbook installs the Apache web server (httpd) on RHEL-based systems using the dnf module. It targets all hosts in the webservers group and ensures that the latest version of Apache is installed.

If the package is missing, it will be installed; if it's outdated, it will be upgraded; otherwise, no changes will be made.

---
- name: install Apache webserver
  hosts: webservers

  tasks:
       - name: install httpd
         dnf:  
          name: httpd  
          State: latest

Example 2: Installing the Apache Web Server on Debian

This playbook installs the Apache web server (apache2) on Debian-based systems such as Ubuntu. It targets all hosts listed under the databases group in your inventory.

---
- name: install Apache webserver
  hosts: databases

  tasks:
       - name: install Apache webserver
         apt:  
          name: apache2  
          State: latest

Use Service Module to Manage Services

The service module allows system administrators to start, stop, update, upgrade, and reload services on the system.

Example 1: Starting Apache Web Server

---
- name: Start service httpd, if not started
  service:
    name: httpd
    state: started

Example 2: Stopping Apache Web Server

---
- name: Stop service httpd
  service:
    name: httpd
    state: stopped

Example 3: Restarting a Network Interface enp2s0

---
- name: Restart network service for interface eth0
  service:
    name: network
    state: restarted
    args: enp2s0

Use Copy Module to Copy Files to Remote Locations

As the name suggests, the copy module copies files from one location on the remote machine to a different location on the same machine.

Example 1: Copying Files from Local to Remote Linux