To follow the examples in this book, it is recommended that you have access to at least two Linux machines for testing on, though more may be preferable to develop the examples more fully. These can be either physical or virtual machines—all examples were developed on a set of Linux virtual machines, but should work just as well on physical ones. In Chapter 5, Using Ansible to Build Virtual Machine Templates for Deployment, we make use of nested virtualization on a KVM virtual machine to build a Linux image. The exact hardware requirements for this are listed at the beginning of this chapter. This will require either access to a physical machine with the appropriate CPU to run the examples on, or a hypervisor that supports nested virtualization (for example, VMware or Linux KVM).

Please be aware that some examples in this book could be disruptive to other services on your network; where there is such a risk, this is highlighted at the beginning of each chapter. I recommend you try out the examples in an isolated test network unless/until you are confident that they will not have any impact on your operations.

Although other Linux distributions are mentioned in the book, we focus on two key Linux distributions—CentOS 7.6 (though if you have access to it, you are welcome to use Red Hat Enterprise Linux 7.6, which should work just as well in most examples), and Ubuntu Server 18.04. All test machines were built from the official ISO images, using the minimal installation profile.

As such, where additional software is required, we take you through the steps needed to install it so that you can complete the examples. If you choose to complete all the examples, you will install software such as AWX, Pulp, Katello, and OpenSCAP. The only exception to this is FreeIPA, which is mentioned in Chapter 10, Managing Users on Linux. Installing a directory server for your enterprise is a huge topic that sadly requires more space than we have in this book—hence, you may wish to explore this topic independently.

The text assumes that you will run Ansible from one of your Linux test machines, but Ansible can actually be run on any machine with Python 2.7 or Python 3 (versions 3.5 and higher) installed (Windows is supported for the control machine, but only through a Linux distribution running in the Windows Subsystem for Linux (WSL) layer available on newer versions of Windows. Supported operating systems for Ansible include (but are not limited to) Red Hat, Debian, Ubuntu, CentOS, macOS, and FreeBSD.

This book uses the Ansible 2.8.x.x series release, although a few examples are specific to Ansible 2.9.x.x, which was released during the course of writing. Ansible installation instructions can be found at https:/​/​docs.​ansible.​com/​ansible/​intro_​installation.​html.

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the Support tab.
3. Click on Code Downloads.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Hands-On-Enterprise-Automation-on-Linux. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://static.packt-cdn.com/downloads/9781789131611_ColorImages.pdf.

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "To start with, let's create a role called loadmariadb."

A block of code is set as follows:

- name: Ensure PostgreSQL service is installed and started at boot time
  service:
    name: postgresql
    state: started
    enabled: yes

Any command-line input or output is written as follows:

$ mkdir /var/lib/tftpboot/EFIx64/centos7

Bold: Indicates a new term, an important word, or words that you see on screen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Select System info from the Administration panel."