Terraformの設定ファイル形式

Terraformは .tf ファイルでインフラストラクチャを定義します。基本的なファイル構成は以下の通りです：

# main.tf
# メインのリソース定義ファイル
provider "aws" {
  region = "ap-northeast-1"
}

resource "aws_instance" "example" {
  ami           = "ami-0c55b159cbfafe1f0"
  instance_type = "t3.micro"
  
  tags = {
    Name = "terraform-example"
  }
}

# variables.tf
# 変数定義ファイル
variable "aws_region" {
  description = "AWS region"
  type        = string
  default     = "ap-northeast-1"
}

variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t3.micro"
}

# outputs.tf
# 出力値定義ファイル
output "instance_public_ip" {
  description = "Public IP of the instance"
  value       = aws_instance.example.public_ip
}

実践的なAWSリソース構築：VPC＋EC2の例

プロジェクトの初期化

新しいディレクトリを作成してプロジェクトを開始します：

mkdir terraform-aws-project
cd terraform-aws-project

# Terraformの初期化
# .terraformディレクトリと .terraform.lock.hcl ファイルが生成されます
terraform init

VPCとEC2インスタンスの完全な構成例

# main.tf
terraform {
  required_version = ">= 1.0"
  required_providers {
    aws = {
      source  = "hashicorp/aws"
      version = "~> 5.0"
    }
  }
}

provider "aws" {
  region = var.aws_region
}

# VPC作成
resource "aws_vpc" "main" {
  cidr_block           = "10.0.0.0/16"
  enable_dns_hostnames = true

  tags = {
    Name = "${var.environment}-vpc"
  }
}

# パブリックサブネット
resource "aws_subnet" "public" {
  vpc_id            = aws_vpc.main.id
  cidr_block        = "10.0.1.0/24"
  availability_zone = "${var.aws_region}a"

  map_public_ip_on_launch = true

  tags = {
    Name = "${var.environment}-public-subnet"
  }
}

# インターネットゲートウェイ
resource "aws_internet_gateway" "main" {
  vpc_id = aws_vpc.main.id

  tags = {
    Name = "${var.environment}-igw"
  }
}

# ルートテーブル
resource "aws_route_table" "public" {
  vpc_id = aws_vpc.main.id

  route {
    cidr_block      = "0.0.0.0/0"
    gateway_id      = aws_internet_gateway.main.id
  }

  tags = {
    Name = "${var.environment}-public-rt"
  }
}

# ルートテーブルの関連付け
resource "aws_route_table_association" "public" {
  subnet_id      = aws_subnet.public.id
  route_table_id = aws_route_table.public.id
}

# セキュリティグループ
resource "aws_security_group" "web" {
  name   = "${var.environment}-web-sg"
  vpc_id = aws_vpc.main.id

  ingress {
    from_port   = 22
    to_port     = 22
    protocol    = "tcp"
    cidr_blocks = [var.ssh_cidr_block]
  }

  ingress {
    from_port   = 80
    to_port     = 80
    protocol    = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

  egress {
    from_port   = 0
    to_port     = 0
    protocol    = "-1"
    cidr_blocks = ["0.0.0.0/0"]
  }

  tags = {
    Name = "${var.environment}-web-sg"
  }
}

# EC2インスタンス
resource "aws_instance" "web" {
  ami                    = data.aws_ami.amazon_linux_2.id
  instance_type          = var.instance_type
  subnet_id              = aws_subnet.public.id
  vpc_security_group_ids = [aws_security_group.web.id]

  user_data = base64encode(file("${path.module}/user_data.sh"))

  tags = {
    Name = "${var.environment}-web-server"
  }
}

# Amazon Linux 2の最新AMIを取得
data "aws_ami" "amazon_linux_2" {
  most_recent = true
  owners      = ["amazon"]

  filter {
    name   = "name"
    values = ["amzn2-ami-hvm-*-x86_64-gp2"]
  }

  filter {
    name   = "root-device-type"
    values = ["ebs"]
  }
}

# variables.tf
variable "aws_region" {
  description = "AWS region"
  type        = string
  default     = "ap-northeast-1"
}

variable "environment" {
  description = "Environment name"
  type        = string
  default     = "dev"
}

variable "instance_type" {
  description = "EC2 instance type"
  type        = string
  default     = "t3.micro"
}

variable "ssh_cidr_block" {
  description = "CIDR block for SSH access"
  type        = string
  default     = "0.0.0.0/0" # 本番環境では必ず制限してください
}

# outputs.tf
output "vpc_id" {
  description = "ID of the VPC"
  value       = aws_vpc.main.id
}

output "instance_public_ip" {
  description = "Public IP address of EC2 instance"
  value       = aws_instance.web.public_ip
}

output "instance_id" {
  description = "ID of EC2 instance"
  value       = aws_instance.web.id
}

output "security_group_id" {
  description = "ID of security group"
  value       = aws_security_group.web.id
}

# user_data.sh
#!/bin/bash
set -e

# システム更新
yum update -y

# Webサーバーをインストール
yum install -y httpd

# サービスを開始
systemctl start httpd
systemctl enable httpd

# 簡単なテストページを作成
cat > /var/www/html/index.html << 'EOF'




  
Terraformで構築されたサーバーです
  
Infrastructure as Codeの力を体験してください！


EOF

計画と実行