Infrastructure and Automation with Ansible

If your day-to-day system administration or development work involves tedious and repetitive operations, Ansible could help you run your tasks while saving you precious time. Ansible is a tool for automating software provisioning, configuration management, and application deployment workflows. Initially developed by Michael DeHaan in 2012, Ansible was acquired by Red Hat in 2015 and is now maintained as an open source project.

In this chapter, you’ll learn about the fundamental concepts of Ansible, along with a variety of hands-on examples. In particular, we’ll explore the following topics:

• Introducing Ansible architecture and configuration management
• Installing Ansible
• Working with Ansible

Technical requirements

First, you should be familiar with the Linux command-line Terminal in general. Intermediate knowledge of Linux will help you understand some of the intricacies of the practical illustrations used throughout this chapter. You should also be proficient in using a Linux-based text editor.

For the hands-on examples, we recommend setting up a lab environment similar to the one we’re using. To replicate this environment, your CPU will need to have at least 6 physical cores and 6 virtual cores (12 in total). A quad-core CPU with hyper-threading is not enough. Also, OpenSSH should be installed on all the hosts. You’ll find related instructions in the Setting up the lab environment section of this chapter. If you don’t configure a lab environment, you will still benefit from the detailed explanations associated with the practical examples in this chapter.

Now, let’s start our journey by covering introductory concepts surrounding Ansible...

Introducing Ansible architecture and configuration management

In the introduction to this chapter, we captured one of the essential aspects of Ansible – it’s a tool for automating workflows. Almost any Linux system administration task can be automated using Ansible. Using the Ansible CLI, we can invoke simple commands to change the desired state of a system. Usually, with Ansible, we execute tasks on a remote host or a group of hosts.

Let’s use the classic illustration of package management. Suppose you’re managing an infrastructure that includes a group of web servers, and you plan to install the latest version of a web server application (Nginx or Apache) on all of them. One way to accomplish this task is to SSH into each host and run the related shell commands to install the latest web server package. If you have a lot of machines, this will be a big task. You could argue that you can write a script to automate this job. This is possible, but then...

Installing Ansible

In this section, we’ll show you how to install Ansible on a control node. On Linux, we can install Ansible in a couple of ways:

• Using the platform-specific package manager (for example, apt on Ubuntu/Debian)
• Using pip, the Python package manager

The Ansible community recommends pip for installing Ansible since it provides the most recent stable version of Ansible. In this section, we’ll use Ubuntu as our distribution of choice. For a complete Ansible installation guide for all major OS platforms, please follow the online documentation at https://docs.ansible.com/ansible/latest/installation_guide/intro_installation.html.

On the control node, Ansible requires Python, so before installing Ansible, we need to make sure we have Python installed on our system.

Important note

Python 2 is no longer supported as of January 1, 2020. Please use Python 3.8 (or newer) instead.

Let’s start by installing Ansible on Ubuntu.

...

Working with Ansible

In this section, we’ll use the Ansible CLI tools extensively to perform various configuration management tasks. To showcase our practical examples, we’ll work with a custom lab environment, and we highly encourage you to reproduce it for a complete configuration management experience.

Here’s a high-level outline of this section:

• Setting up the lab environment
• Configuring Ansible
• Using Ansible ad hoc commands
• Using Ansible playbooks
• Using templates with Jinja2
• Using Ansible roles

Let’s start with an overview of the lab environment.

Setting up the lab environment

Our lab uses Kernel-based Virtual Machine (KVM) as a hypervisor for the virtual environment, but any other hypervisor will do. Chapter 11, Working with Virtual Machines, describes the process of creating Linux virtual machines (VMs) in detail. We deployed the following VMs using Ubuntu Server LTS to mimic a real-world configuration management...

Summary

In this chapter, we covered significant ground in terms of Ansible. Due to this chapter’s limited scope, we couldn’t capture all of Ansible’s vast number of features. However, we tried to provide an overarching view of the platform, from Ansible’s architectural principles to configuring and working with ad hoc commands and playbooks. You learned how to set up an Ansible environment, with several managed hosts and a control node, thereby emulating a real-world deployment at a high level. You also became familiar with writing Ansible commands and scripts for typical configuration management tasks. Most of the commands and playbooks presented throughout this chapter closely resemble everyday administrative operations.

Whether you are a systems administrator or a DevOps engineer, a seasoned professional, or on the way to becoming one, we hope this chapter brought new insights to your everyday Linux administration tasks and automation workflows. The...

Questions

Let’s try to wrap up some of the essential concepts we learned about in this chapter by completing the following quiz:

1. What are idempotent operations or commands in Ansible?
2. You want to set up passwordless authentication with your managed hosts. What steps should you follow?
3. What is the ad hoc command for checking communication with all your managed hosts?
4. Enumerate a few Ansible modules. Try to think of a configuration management scenario where you could use each module.
5. Think of a simple playbook that monitors the memory that’s available on your hosts and will notify you if that memory is above a given threshold.

Further reading

Here are a few resources we found helpful for learning more about Ansible internals:

• Ansible documentation: https://docs.ansible.com/
• Ansible use cases, by Red Hat: https://www.ansible.com/use-cases
• Dive into Ansible – From Beginner to Expert in Ansible [Video], by James Spurin, Packt Publishing (https://www.packtpub.com/product/dive-into-ansible-from-beginner-to-expert-in-ansible-video/9781801076937)
• Practical Ansible 2, by Daniel Oh, James Freeman, Fabio Alessandro Locati, Packt Publishing (https://www.packtpub.com/product/practical-ansible-2/9781789807462)