Terraform Basics

What is Terraform?

Terraform is a tool for building, changing, and versioning infrastructure safely and efficiently. It is used to create/build an environment.
Terraform can manage existing and popular service providers as well as custom in-house solutions.
Terraform can be used for multiple cloud providers, like AWS, Azure, or GCP.
Terraform is developed in the GO language.
Terraform templates are written in a custom Domain Specific Language (DSL) called HashiCorp Configuration Language or HCL.
Terraform templates/files end with a .tf extension.

Terraform Definition: Terraform is an open-source Infrastructure as Code (IaC) tool developed by HashiCorp. It allows you to define and provision infrastructure in a declarative configuration language. Terraform supports multiple cloud providers, including AWS, Azure, Google Cloud, and more.

Key Concepts:

Configuration files describe to Terraform the components needed to run a single application or your entire data center.
Execution plan: Terraform generates an execution plan describing what it will do to reach the desired state, and then executes it to build the described infrastructure.
Versioning: As the configuration changes, Terraform is able to determine what changed and create incremental execution plans which can be applied.
The infrastructure Terraform can manage includes low-level components such as compute instances, storage, and networking , as well as high-level components such as DNS entries, SaaS features, etc.
Declarative Configuration: Terraform uses declarative syntax, where you define the desired state of your infrastructure. It then determines the necessary actions to bring the actual infrastructure to that state.
Infrastructure as Code (IaC): Terraform enables you to manage and version your infrastructure as code, providing the benefits of version control, collaboration, and repeatability.
Providers: Terraform uses providers to interact with various infrastructure platforms. For AWS, you would use the AWS provider to manage resources within the AWS environment.

How Terraform Helps with AWS:

Resource Provisioning: Terraform allows you to define AWS resources such as EC2 instances, S3 buckets, and RDS databases in code. It then provisions and manages these resources based on your configurations.
Infrastructure Versioning: Since Terraform configurations are code, you can version control them using tools like Git. This facilitates collaboration, rollback to previous states, and tracking changes over time.
State Management: Terraform maintains a state file that keeps track of the current state of your infrastructure. This state is crucial for understanding what Terraform has created and managing changes to the infrastructure.

How does Terraform work?

Terraform creates and manages resources on cloud platforms and other services through their application programming interfaces (APIs).
Providers enable Terraform to work with virtually any platform or service with an accessible API.

Terraform workflow

1. Write Infrastructure Code (HCL):

You start by writing Terraform configuration files using HashiCorp Configuration Language (HCL).
These files define the infrastructure components you want to create, such as virtual machines, networks, or storage.

2. Initialize:

Run the terraform init command in the directory where your configuration files are located.
This command downloads the necessary providers and sets up the backend to store the Terraform state.

3. Plan:

Execute terraform plan to preview the changes Terraform will make to your infrastructure. It doesn't make any changes yet; it just shows you what will happen.
This is a safety check before making any modifications.

4. Apply:

If the plan looks good, you can apply the changes using terraform apply.
Terraform will prompt you to confirm that you want to make the proposed changes. If you're satisfied, type "yes," and Terraform will create or update your infrastructure according to the configuration.

5. Review and Iterate:

After applying the changes, you can review the outputs and make any necessary adjustments to your configuration.
If you need to make changes, go back to step 3 (plan) and then apply again.

6. Destroy (Optional):

If you want to tear down the infrastructure created by Terraform, you can use terraform destroy.
This command will prompt you to confirm the destruction of resources defined in your configuration.

7. Version Control:

It's a good practice to use version control (e.g., Git) to manage your Terraform configurations.
This helps track changes, collaborate with others, and roll back to previous versions if needed.

Let's connect and explore Terraform and AWS.

References :

What is Terraform

Blog

Terraform Basics

Venkatesh K

What is Terraform?