Ansible: Up and Running

Preface

Why I Wrote This Book

When I was writing my first web application, using Django, the popular Python-based framework, I remember the sense of accomplishment when the app was finally working on my desktop. I would run django manage.py runserver, point my browser to http://localhost:8000, and there was my web application in all its glory.

Then I discovered there were all of these…things I had to do, just to get the darned app to run on the Linux server. In addition to installing Django and my app onto the server, I had to install Apache and the mod_python module so that Apache could run Django apps. Then I had to figure out the right Apache configuration file incantation so that it would run my application and serve up the static assets properly.

None of it was hard, it was just a pain to get all of those details right. I didn’t want to muck about with configuration files, I just wanted my app to run. Once I got it working, everything was fine…until, several months later, I had to do it again, on a different server, at which point I had to start the process all over again.

Eventually, I discovered that this process was Doing It Wrong. The right way to do this sort of thing has a name, and that name is configuration management. The great thing about using configuration management is that it’s a way to capture knowledge that always stays up-to-date. No more hunting for the right doc page or searching through your old notes.

Recently, a colleague at work was interested in trying out Ansible for deploying a new project, and he asked me for a reference on how to apply the Ansible concepts in practice, beyond what was available in the official docs. I didn’t know what else to recommend, so I decided to write something to fill the gap—and here it is. Alas, this book comes too late for him, but I hope you’ll find it useful.

Who Should Read This Book

This book is for anyone who needs to deal with Linux or Unix-like servers. If you’ve ever used the terms systems administration, operations, deployment, configuration management, or (sigh) DevOps, then you should find some value here.

Although I have managed my share of Linux servers, my background is in software engineering. This means that the examples in this book tend toward the deployment end of the spectrum, although I’m in agreement with Andrew Clay Shafer ([webops]) that the distinction between deployment and configuration is unresolved.

Navigating This Book

I’m not a big fan of book outlines: Chapter 1 covers so and so, Chapter 2 covers such and such, that sort of thing. I strongly suspect that nobody ever reads them (I never do), and the table of contents is much easier to scan.

This book is written to be read start to finish, with later chapters building on the earlier ones. It’s written largely in a tutorial style, so you should be able to follow along on your own machine. Most of the examples are focused on web applications.

Conventions Used in This Book

The following typographical conventions are used in this book:

Italic

Indicates new terms, URLs, email addresses, filenames, and file extensions.

Constant width

Used for program listings, as well as within paragraphs to refer to program elements such as variable or function names, databases, data types, environment variables, statements, and keywords.

Constant width bold

Shows commands or other text that should be typed literally by the user.

Constant width italic

Shows text that should be replaced with user-supplied values or by values determined by context.

Tip

This icon signifies a tip, suggestion, or general note.

Warning

This icon indicates a warning or caution.

Online Resources

Code samples from this book are available at this book’s GitHub page. There is ample official Ansible documentation available for reference.

I maintain a few Ansible quick reference pages on GitHub as well.

The Ansible code is on GitHub, split across three repositories:

• Main repo

• Core modules

• Extra modules

Bookmark the Ansible module index; you’ll be referring to it constantly as you use Ansible. Ansible Galaxy is a repository of Ansible roles contributed by the community. The Ansible Project Google Group is the place to go if you have any questions about Ansible.

If you’re interested in contributing to Ansible development, check out the Ansible Development Google Group.

For real-time help with Ansible, there’s an active #ansible IRC channel on irc.freenode.net.

Supplemental material (code examples, exercises, etc.) is available for download at https://github.com/lorin/ansiblebook.

This book is here to help you get your job done. In general, if example code is offered with this book, you may use it in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.

We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: “Ansible: Up and Running by Lorin Hochstein (O’Reilly). Copyright 2015 Lorin Hochstein, 978-1-491-91532-5.”

If you feel your use of code examples falls outside fair use or the permission given above, feel free to contact us at [e-mail].

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Acknowledgments

Thanks to Jan-Piet Mens, Matt Jaynes, and John Jarvis for reviewing drafts of the book and providing feedback. Thanks to Isaac Saldana and Mike Rowan at SendGrid for being so supportive of this endeavor. Thanks to Michael DeHaan for creating Ansible and shepherding the community that sprang up around it, as well as for providing feedback on the book, including an explanation of why he chose to use the name “Ansible.” Thanks to my editor, Brian Anderson, for his endless patience in working with me.

Thanks to Mom and Dad for their unfailing support; my brother Eric, the actual writer in the family; and my two sons, Benjamin and Julian. Finally, thanks to my wife, Stacy, for everything.