SaltStack (or Salt, for short) is an open source project that was started by Thomas Hatch in 2011. It was originally intended to be a lightning-fast remote execution system. Later, the various pieces that make up the Salt that we know today were added on top of this flexible layer. Salt is now one of the most popular open source projects in the world and one of the most popular infrastructure management platforms.
The project is managed by SaltStack, Inc., a company dedicated to preserving the open source nature of the software. SaltStack, Inc. provides service, long-term support, and custom code in their enterprise product, and supports the open source Salt project with a team of dedicated engineers.
Why do you care? What can Salt do for you?
Salt is the easiest, most powerful way to manage your servers. Whether you have a few, hundreds, or even tens of thousands of servers, you can use Salt to manage them from a single central point. You can use it to flexibly target any subset of your servers to run commands or accomplish tasks. You can use the state system to define the state of your infrastructure in a data-driven way and then enforce that state in seconds, with a single command. You can even create a reactive, self-healing infrastructure using the event system. Salt is written in Python and designed to be easy to extend for your own specific use-cases or purposes.
We're going to learn how to do all this and more in these pages. By the end of this book, you will have the knowledge you need to begin making the management of your infrastructure easier with Salt.
Let's get to it!
Chapter 1, Diving In – Our First Salt Commands, will discuss how to install Salt and execute basic commands.
Chapter 2, Controlling Your Minions with Remote Execution, will show how to use Salt to accomplish tasks on your minions through remote execution.
Chapter 3, Execution Modules – Write Your Own Solution, will discuss how to write your own custom remote execution modules to extend Salt for your own purposes.
Chapter 4, Defining the State of Your Infrastructure, will discuss how to use Salt States to define and enforce the state of your infrastructure.
Chapter 5, Expanding Our States with Jinja2 and Pillar, will discuss how to make your states more flexible and powerful by using Jinja2 and Pillar data.
Chapter 6, The Highstate and Environments, will show how to structure your states into environments and enforce the state of your entire infrastructure using a single command.
Chapter 7, Using Salt Cloud to Manage Virtual Minions, will show how to manage your cloud virtual machines using salt-cloud to create and manage VMs.
Chapter 8, The Reactor and the Event System, will show how to make your infrastructure automatically react to changes by using the reactor and event system built into Salt.
Chapter 9, Security Best Practices in Salt, will show how to secure your SaltStack infrastructure from attackers.
Chapter 10, How Can I Get Involved?, will show how to go beyond this book and learn more about Salt, as well as how to get involved in the SaltStack community.
You will need access to a Linux machine to run the examples in this book. The preferred operating system is Ubuntu 14.04, but any major distribution of Linux is acceptable. If you use an operating system other than Ubuntu 14.04, your output may differ from the example output in the book.
The biggest target audience for this book is system administrators. However, anyone who works with servers, whether application/web developers, system administrators, or hobbyists, will be able to use to this book to learn how to manage their servers/infrastructure easily and consistently.
No prior Salt knowledge is assumed. However, even Salt veterans will find new knowledge and best practices to apply in their own infrastructures. This book is for anyone who wants to better manage their infrastructure with Salt.
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Now, you must open the file
/etc/apt/sources.list and add the following line."
A block of code is set as follows:
test_state file.managed: - name: /tmp/test.txt - source: salt://test.txt - user: root - group: root - mode: 644
When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
- name: /tmp/test.txt
- source: salt://test.txt
- user: root
- group: root
- mode: 644
Any command-line input or output is written as follows:
# cp /usr/src/asterisk-addons/configs/cdr_mysql.conf.sample /etc/asterisk/cdr_mysql.conf
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Continue the installation process by clicking Next and agreeing to the license agreement."
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