Terraform was first released in July 2014 by a company named HashiCorp. It is the same company that brought some tools, 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:

Terraform is an open...

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 Zip archive. Unfortunately, HashiCorp does not provide native packages for operating systems. That means the first step is too install unzip. Depending on your package manager, this could be done by running sudo yum install unzip or sudo apt-get install unzip or might be 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 this folder is available in your PATH environment variable. A full installation command sequence could look as follows...

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 a 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 TLS provider to generate keys and certificates.

Nevertheless, most providers are dealing with one or another external API and require configuration. In this book, we will be using the AWS provider. Before we configure it, let's have a short introduction to AWS. If you are already familiar with...

Amazon Web Services is a cloud offering from Amazon, an online retail giant. Back in 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 don't need to manage underlying 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) that were released and anyone could pay to use them.

Fast forward 10 years. AWS now has over 70 different services, covering practically everything modern infrastructure would need. It has services for virtual networking, queue processing, transactional e-mails, storage, DNS, relational databases...

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.

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 template itself is generated or read by a machine.

We can configure credentials in the following ways.

    provider "aws" {
        access_key = "xxxxxxxxxxxxx"
        secret_key = "xxxxxxxxxxxxx"
        region = "us-east-1"
    }

Resources are components of your infrastructure. It can be something as complex as a complete virtual server, or something as simple as a DNS record. Each resource belongs to a provider, and the type of the resource is suffixed with the provider name. The configuration of a resource takes the following form:

resource "provider-name_resource-type" "resource-name" { 
  parameter_name = parameter_value 
} 

The combination of resource type and resource name must be unique in your template; otherwise Terraform will complain.

There are three types of things you can configure inside resource block: resource-specific parameters, meta-parameters, and provisioners. For now, let's focus on resource-specific parameters. They are unique to each resource type.

We will create an EC2 instance. The aws_instance resource is responsible for this job. To create an instance, we need to set at least two parameters: ami and instance_type. Some parameters are required...