Chapter 1, Infrastructure Automation, covers infrastructure automation in general, why is it needed at all (with a list of the main reasons to do it) and which tools exist to solve this problem. By the end of this chapter you will know which problem Terraform solves and why it is the best tool for particular infrastructure automation tasks.

Chapter 2, Deploying First Server, walks through all the necessary steps to install Terraform, gives a short overview of AWS and EC2, and explain in detail how to create your very first EC2 instance with Terraform.

Chapter 3, Resource Dependencies and Modules, explains one of most important features of Terraform: dependency graph. You will figure out how dependencies work and see it in practice by extending the template from previous chapter. At the moment we find out our template is too big, we will use Terraform modules to DRY our code and also use more advanced dependency features.

Chapter 4, Storing and Supplying Configuration, teaches how to make Terraform templates more configurable. You will see all the possible ways to supply data to Terraform templates, to basic variables to using any external data source.

Chapter 5, Connecting with Other Tools, talks about how you can connect Terraform templates to external tools. It shows how to combine Terraform and Ansible, Puppet, or Chef, how to provision servers, and how to run Inspec tests against them.

Chapter 6, Scaling and Updating Infrastructure, dives deep into managing existing infrastructures with Terraform. It gives an overview of the various ways to perform updates with Terraform and explains what Immutable Infrastructure is and how to use it with Terraform. It gives a full example of performing both rolling updates and blue-green deployments, as well as tricks on running smaller updates.

Chapter 7, Collaborative Infrastructure, provides best practices of using Terraform in a team. It shows how to refactor and split Terraform templates into remote modules, how to organize your code to be re-usable, and how to handle sensitive data inside Terraform templates. It also teaches how to do full Continuous Integration of a Terraform-based infrastructure.

Chapter 8, Future of  Terraform, speculates on the future of Terraform. It also recaps everything learned so far and gives some extra thoughts and hints on topics that were too small too deserve a separate chapter.

This book assumes a basic level of understanding the Linux operating system. The book will go through configuring numerous AWS resources. Being familiar with AWS is a plus, but is not required, as all required services will be explained. Usage of some cloud services in this book will require you to spend a dollar or two on them. Although the book assumes Linux as the primary workstation operating system, all of the content applies to MacOS and most of it will work the same way on Windows as well.

Internet connectivity is required to install the necessary tools, including Terraform. It is also required to perform any Terraform operations.

This book is essentially intended to both software developers and system administrators, as well as specialists who have knowledge of both areas: system reliability engineers, DevOps engineers, cloud architects and so on.

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: "For some reason, instead of using DNS server, you want to hardcode the IP address of this box to the /etc/hosts file with a domain name repository.internal."

A block of code is set as follows:

host { 'repository.internal':
  ip => '192.168.0.5',
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

resource "null_resource" "app_server_provisioner" {
  triggers {
    server_id = "${join(",", aws_instance.app-server.*.id)}"
  }
  connection {
    user = "centos"
    host = "${element(aws_instance.app-server.*.public_ip, count.index)}"
  }
  provisioner "file" {
    source = "${path.module}/setup.pp"
    destination = "/tmp/setup.pp"
  }

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

$> curl -O https://releases.hashicorp.com/terraform/0.8.2/terraform_0.8.2_linux_amd64.zip
$> sudo unzip terraform_0.8.2_linux_amd64.zip -d /usr/local/bin/

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: "Click on Launch Instance."

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