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Discover Infrastructure as Code using Terraform. Get job-ready in months, not years by confidently building in-demand skills. Learn HCL, manage resources, and deploy on AWS, Azure, Google Cloud.

Course cover Infrastructure as Code using Terraform.png

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Infrastructure as code (IaC) is a standard practice of maintaining infrastructure configuration as code. Terraform is a cross-platform tool that introduces the HashiCorp Configuration Language (HCL) for the provisioning of infrastructures on different cloud platforms like Azure, AWS, and Google Cloud.

First you’ll learn about the basics of IaC and the tools used for it. Next, you’ll learn about Terraform, how to deploy resources using it, and the Terraform state file. Then you’ll cover the basics of HCL, followed by how to work with outputs, expressions, and loops. You’ll also cover local and remote provisioners, and learn how to employ HCL to provision and manage resources using different concepts like modules, variables, provisioners, and the Terraform state file. Finally, you’ll learn how to use the Terraform Cloud.

By the end of this course, you’ll be able to provision, delete, and update resources on a cloud platform using Terraform. Knowing how to use Terraform effectively will set you up for success.

Infrastructure as Code Using Terraform

# Overview

Previously, we learned how important the Terraform state file is and how it's a true reflection of our existing infrastructure. We'll further explore a state file and how it outlines our resources as well as the interconnection between the resources. Terraform equally provides us a CLI tool, the `terraform state` command, to be able to work with the state file instead of modifying the file manually.

# Terraform state file example
Let's consider the example where we created a VPC and a subnet on AWS. The generated state file `terraform.tfstate` will look as follows:

available

sample_private_subnet

sample_vpc

# Breaking things down

From the above `terraform.tfstate` file, we can see how the existing resources on AWS are outlined block by block. We have three major resource blocks, including:

1. `aws_availability_zones` (**lines 8–41**): This is a data resource we create using Terraform to list the availability zones we have.

2.  `aws_subnet` (**lines 42–87**): This is a managed resource for our VPC on AWS.

3. `aws_vpc` (**lines 88–134**): This is a managed resource for our subnet inside the specified VPC on AWS.

# Working with the Terraform state command

The Terraform state command gives us the ability to work on the `terraform.tfstate` file from the command line instead of modifying the file manually.

The available subcommands include:

- `terraform state list`: This is used to list resources in the state.
- `terraform state mv`: This is used to move an item in the state.
- `terraform state pull`: This is used to pull the current state and output to stdout.
- `terraform state push`: This is used to update a remote state from a local state file.
- `terraform state replace-provider`: This is used to replace the provider in the state.
- `terraform state rm`: This is used to remove instances from the state.
- `terraform state show`: This is used to show a resource in the state.

We can follow the steps below in the terminal provided at the end of the lesson to list the resources in our Terraform state and then show details about these resources.

1. Initialize the Terraform backend using the command below:

   ```
   terraform init
   ```
2. Show the execution plan by using the command below:
   ```
   terraform plan
   ```
3. Apply the execution plan and deploy resources (a VPC and a subnet) using the command below and then a "yes" at the prompt.
   ```
   terraform apply
   ```
4. Confirm that there's a `terraform.tfstate` file by typing the command below on the terminal:
   ```
   ls
   ```
5. List the resources available in the Terraform state by typing the command below in the terminal:
   ```
   terraform state list 
   ```
6. Get the details about the VPC resource we created by typing the command below in the terminal:
   ```
   terraform state show aws_vpc.sample_vpc
   ```
7. Destroy the resources created by using the command below:
   ```
   terraform destroy
   ```

# Playground

Please use the terminal below to execute the steps above.

Learn about the format of a Terraform state file and how to modify it.

Getting Started

Infrastructure as Code

The Basics of Terraform

The Basics of the HashiCorp Configuration Language

Terraform Provisioners

Introduction to Terraform Essentials

Manage Infrastructure using Terraform on Google Cloud Platform

Conclusion

Deploying AWS Infrastructure with Terraform

Getting Familiar with the Terraform State File

Overview