Practical IaC with Terraform: From Module Design to State Management

Why You Need IaC

Infrastructure created by clicking around cannot be reproduced. Defining infrastructure as code with Terraform enables version control, code review, and automation.

Project Directory Structure

CODE

terraform/
├── environments/
│   ├── prod/
│   │   ├── main.tf
│   │   └── terraform.tfvars
│   └── staging/
└── modules/
    ├── vpc/
    ├── eks/
    └── rds/

Module Design

HCL

# modules/vpc/main.tf
resource "aws_vpc" "main" {
  cidr_block           = var.cidr_block
  enable_dns_hostnames = true

  tags = merge(var.common_tags, {
    Name = "${var.project}-${var.environment}-vpc"
  })
}

variable "cidr_block" {
  type    = string
  default = "10.0.0.0/16"

  validation {
    condition     = can(cidrhost(var.cidr_block, 0))
    error_message = "유효한 CIDR 형식이어야 합니다."
  }
}

Remote State Management

HCL

terraform {
  backend "s3" {
    bucket         = "my-company-terraform-state"
    key            = "prod/terraform.tfstate"
    region         = "ap-northeast-2"
    encrypt        = true
    dynamodb_table = "terraform-state-lock"
  }
}

Bash

# State 잠금 테이블 생성
aws dynamodb create-table \
  --table-name terraform-state-lock \
  --attribute-definitions AttributeName=LockID,AttributeType=S \
  --key-schema AttributeName=LockID,KeyType=HASH \
  --billing-mode PAY_PER_REQUEST

CI/CD Integration

YAML

name: Terraform
on:
  pull_request:
    paths: ['terraform/**']

jobs:
  plan:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: hashicorp/setup-terraform@v3
      - run: terraform init
      - run: terraform fmt -check -recursive
      - run: terraform validate
      - run: terraform plan -out=tfplan

Practical Tips

Never commit tfstate files to git (.gitignore)

CODE

*.tfstate
*.tfstate.backup
.terraform/

Masking sensitive variables

HCL

variable "db_password" {
  type      = string
  sensitive = true
}

Terraform is not just a tool. It is a cultural shift that changes how your team operates infrastructure.

References: Official Docs

The primary source for the behavior, configuration, and errors covered in this post is the official documentation below. Check there for version-specific options and exact behavior.

Terraform official documentation

확인 정보

#Terraform #IaC #인프라자동화 #DevOps #GitOps

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