Terraform Basics

What is Terraform?

Terraform is an open-source Infrastructure as Code (IaC) tool created by HashiCorp.
It allows you to define, provision, and manage infrastructure across multiple cloud providers using a declarative configuration language called HashiCorp Configuration Language (HCL).

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Terraform Core Concepts

Providers:
Plugins that allow Terraform to interact with cloud providers (like AWS, Azure, GCP) or other APIs.

Resources:
Components that Terraform manages, such as virtual machines, storage accounts, or networking services.

Variables:
Allow you to make your Terraform code dynamic and reusable.

Outputs:
Display information after your Terraform run, such as IP addresses or URLs.

State File:
Terraform keeps track of the infrastructure it manages using a state file (terraform.tfstate).
This file maps your configuration to real-world resources.

Modules:
Containers for multiple resources that are used together. Modules can be reused across projects.

Provisioners:
Allow you to execute scripts or commands on a local or remote machine after a resource is created.

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Basic Terraform Workflow

1. Write Configuration:
   Define infrastructure in .tf files using HCL.

2. Initialize (terraform init):
   Initialize the working directory by downloading the necessary provider plugins.

3. Validate (terraform validate):
   Check whether the configuration is valid.

4. Plan (terraform plan):
   Preview the changes Terraform will make without applying them.

5. Apply (terraform apply):
   Apply the changes to reach the desired infrastructure state.

6. Destroy (terraform destroy):
   Remove all the infrastructure managed by Terraform.

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Common Terraform Commands

Command	Description
terraform init	Initialize the working directory.
terraform validate	Validate the configuration.
terraform plan	Preview changes before applying.
terraform apply	Apply the changes.
terraform destroy	Destroy all managed infrastructure.

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Terraform Best Practices

Use Remote Backend for State Files:
Always store terraform.tfstate in a remote backend like S3 with DynamoDB locking to avoid losing important data.

Always Version Control:
Save .tf files in a version control system like Git to track changes and collaborate easily.

Use Variables and Outputs Wisely:
Keep your configurations modular, reusable, and easy to maintain.

Write Modular Code:
Break down your Terraform code into modules to promote reusability and scalability.

Enable State Locking:
Prevent concurrent operations on the same infrastructure by enabling state locking.

Keep Sensitive Data Secure:
Never hardcode secrets or passwords. Use environment variables, Vault, or other secret management tools.

Format and Validate Code:
Always run terraform fmt and terraform validate before pushing your code.

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