Terraform was first released in July 2014 by a company named HashiCorp. It is the same company that brought us tool, such as Vagrant, Packer, and Vault. Being the fifth tool in the HashiCorp stack, it focused on providing a way to describe the complete infrastructure as code:

In this book, we will focus on using Terraform in a Linux environment. The general usage of the tool should be the same on all platforms, though some advanced topics and practices discussed in later chapters might apply only to Linux systems.

As mentioned in the previous section, Terraform is distributed as a single binary, packaged inside a ZIP archive. Unfortunately, HashiCorp does not provide native packages for operating systems. That means the first step is to install unzip. Depending on your package manager, this could be done by running sudo yum install unzip, or sudo apt-get install unzip or it might even already be installed. In any case, after making sure that you can unarchive the ZIP files, proceed to downloading Terraform from the official website, https://www.terraform.io/downloads.html.

Unzip it to any convenient folder. Make sure that...

Providers are something you use to configure access to the service you create resources for. For example, if you want to create AWS resources, you need to configure the AWS provider. This would specify credentials to access the APIs of many AWS services.

At the time of writing, Terraform has more than 40 providers. This impressive list includes not only major cloud providers such as AWS and Google Cloud, but also smaller services, such as Fastly, a Content Delivery Network (CDN) provider.

Not every provider requires explicit configuration. Some of them do not even deal with external services. Instead, they provide resources for local entities. For example, you could use a TLS provider to generate keys and certificates.

Nevertheless, most providers deal with one or another external API and require configuration. In this book, we will be using the AWS...

Amazon Web Services is a cloud offering from Amazon, an online retail giant. Back in the early 2000s, Amazon invested money in an automated platform, which would provide services for things such as network, storage, and computation to Amazon developers. Developers then didn't need to manage underlying the infrastructure. Instead, they would use provided services via APIs to provision virtual machines, storage buckets, and so on.

The platform, initially built to power Amazon itself, was open for public usage in 2006. The first released service was Simple Queue Service (SQS), followed by the two most commonly used AWS services--Simple Storage Service (S3) and Elastic Compute Cloud (EC2) were released and anyone could pay to use them.

Fast forward 10 years. AWS now has over 70 different services, covering practically everything a modern infrastructure...

We will look at three ways of creating an EC2 instance: manually via the Management Console, with the AWS Command Line Interface (CLI), and with Terraform.

Just to get a feel of the AWS Management Console and to fully understand how much Terraform simplifies working with AWS, let's create a single EC2 instance manually:

1. Log in to the console and choose EC2 from the list of services:

2. Click on Launch Instance:

3. Choose AWS Marketplace from the left sidebar, type Centos in the search box, and click on the Select button for the first search result:

4. On each of the next pages, just click on Next till you reach the end of the process and...

Before using Terraform to create an instance, we need to configure AWS provider. This is the first piece of code we will write in our template. Templates are written in a special language named HashiCorp Configuration Language (HCL). More details about HCL can be found at https://github.com/hashicorp/hcl. You can also write your templates in JSON, but this is recommended only if a template is itself generated or read by a machine.

We can configure credentials in the following ways.

With this method, you just hardcode your access keys right inside your template. It looks as follows:

    provider "aws" {
        access_key = "xxxxxxxxxxxxx"
        secret_key =...