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Terraform

Introduction​

This cheat sheet provides a quick reference for some common Terraform commands and concepts. Terraform is an open-source infrastructure as code (IAC) tool used to define, provision, and manage infrastructure resources.

Installation​

To use Terraform, you need to install it on your system. Installation methods vary depending on your operating system. Refer to the official Terraform documentation for installation instructions.

Terraform Concepts​

Configuration Files​

Terraform uses configuration files written in HashiCorp Configuration Language (HCL) to define and manage infrastructure.

  • Create a basic Terraform configuration file (e.g., main.tf):

    provider "aws" {
      region = "us-east-1"
    }

    resource "aws_instance" "example" {
      ami           = "ami-0c55b159cbfafe1f0"
      instance_type = "t2.micro"
    }

  • Use variables, outputs, and modules in configuration files for more advanced infrastructure definitions.

Providers​

Providers define the target cloud or infrastructure platform where resources will be created. Terraform supports providers for various cloud providers, including AWS, Azure, and Google Cloud.

  • Declare a provider block in the configuration file:
    provider "aws" {
      region = "us-west-2"
    }

Resources​

Resources represent the infrastructure components you want to create, such as virtual machines, databases, and networks.

  • Define a resource block in the configuration file:
    resource "aws_instance" "example" {
      ami           = "ami-0c55b159cbfafe1f0"
      instance_type = "t2.micro"
    }

Variables​

Variables allow you to parameterize your Terraform configuration, making it reusable and easier to manage.

  • Declare a variable block in the configuration file:
    variable "instance_count" {
      type    = number
      default = 1
    }

Outputs​

Outputs allow you to define values that should be displayed after Terraform applies the configuration.

  • Declare an output block in the configuration file:
    output "instance_ip" {
      value = aws_instance.example[*].public_ip
    }

State​

Terraform maintains a state file (by default, terraform.tfstate) that tracks the actual infrastructure state. It's essential for Terraform to understand the current state and make necessary changes.

Terraform Command-Line​

  • Initialize a Terraform configuration:

    terraform init

  • Validate the Terraform configuration:

    terraform validate

  • Create or update infrastructure resources:

    terraform apply

  • Plan and preview changes:

    terraform plan

  • Destroy resources:

    terraform destroy

  • Show Terraform state:

    terraform show

Conclusion​

This cheat sheet covers some common Terraform commands and concepts. Terraform simplifies the management of infrastructure as code, enabling you to provision and manage resources efficiently; refer to the official Terraform documentation for more in-depth information and advanced usage.