Terraform

Terraform

Terraform by HashiCorp is the leading Infrastructure as Code tool. It uses a declarative language (HCL) to provision and manage resources across cloud providers.

Terraform Workflow

  ┌─────────┐    ┌─────────┐    ┌─────────┐    ┌─────────┐
  │  write  │───▶│  init   │───▶│  plan   │───▶│  apply  │
  │  config │    │         │    │         │    │         │
  │  (.tf)  │    │ Download│    │ Preview │    │ Create/ │
  │         │    │ providers│   │ changes │    │ update  │
  └─────────┘    └─────────┘    └─────────┘    └─────────┘

  terraform init     — Initialize, download providers
  terraform plan     — Preview what will change
  terraform apply    — Execute the changes
  terraform destroy  — Tear down infrastructure

Terraform Example

  # main.tf
  provider "aws" {
    region = "us-east-1"
  }

  resource "aws_vpc" "main" {
    cidr_block = "10.0.0.0/16"
    tags = {
      Name = "production-vpc"
    }
  }

  resource "aws_subnet" "web" {
    vpc_id     = aws_vpc.main.id
    cidr_block = "10.0.1.0/24"
    tags = {
      Name = "web-subnet"
    }
  }

  resource "aws_instance" "web" {
    ami           = "ami-0c55b159cbfafe1f0"
    instance_type = "t3.micro"
    subnet_id     = aws_subnet.web.id

    tags = {
      Name = "web-server"
    }
  }

Terraform State

  State File (terraform.tfstate):
  ┌─────────────────────────────────────┐
  │  Maps real-world resources to your  │
  │  configuration. Tracks metadata,   │
  │  dependencies, and IDs.            │
  │                                     │
  │  Best Practice: Use remote state    │
  │  ┌─────────────────────────────┐    │
  │  │ S3 + DynamoDB locking       │    │
  │  │ Terraform Cloud             │    │
  │  │ Consul                      │    │
  │  └─────────────────────────────┘    │
  └─────────────────────────────────────┘

Key Concepts

• Providers — Plugins for cloud platforms (AWS, GCP, Azure)
• Resources — Infrastructure objects to create
• Data Sources — Query existing resources
• Modules — Reusable, composable Terraform packages
• Workspaces — Manage multiple environments with the same config