Terraformとは？

IaC(Infrastructure as Code)を実現するためのツール
オープンソースで、HashCorpにより、Go言語で開発された
インフラ構成を構造化された構成ファイルによって、自動管理可能
コードを見るだけで構成内容が理解でき、コードはGit管理されるため、コードレビューが可能

ソース概要

Structure

Resources (main.tf...)
Input (variables.tf)
Output (outputs.tf)

main.tf

AWSを利用すること、及びバージョンとリージョンを指定します。
AWSにアクセスするにはクレデンシャル情報を指定する。

# definition provider
provider "aws" {
  version = "~> 2.0"
  region = "${var.provider_region}"
  access_key = "${var.secret_access_key}"
  secret_key = "${var.secret_key}"
}

resource.tf

UbuntuとPostgresデータベースを宣言するリソースファイルは、以下

resource "aws_instance" "web" {
  ami = "${data.aws_ami.ubuntu.id}"
  instance_type = "${var.server_instance_type}"

  tags = {
    Name = "${var.server_tag_name}"
  }
}

data "aws_ami" "ubuntu" {
  most_recent = true

  filter {
    name = "name"
    values = ["ubuntu/images/hvm-ssd/ubuntu-trusty-14.04-amd64-server-*"]
  }

  owners = ["099720109477"]
}

resource "aws_db_instance" "default" {
  allocated_storage = "${var.db_allocated_storage}"
  storage_type = "${var.db_storage_type}"
  engine = "${var.db_engine}"
  engine_version = "${var.db_engine_version}"
  instance_class = "${var.db_instance_class}"
  name = "${var.db_database_name}"
  username = "${var.db_database_username}"
  password = "${var.secret_db_database_password}"
  final_snapshot_identifier = "${var.db_snapshot_identifier}"
}

var.tf

定義内に出てくる変数の設定

variable "provider_region" {
 description = "Provider region"
 default = "us-east-1"
}

variable "secret_access_key" {
 description = "Provider access key"
 default = "YOUR-ACCESS-KEY"
}

variable "secret_key" {
 description = "Provider secret key"
 default = "YOUR-SECRET-KEY"
}

# instance web variables
variable "server_instance_type" {
  description = "Server instance type"
  default = "t2.micro"
}

variable "server_tag_name" {
  description = "Server tag name"
  default = "JeSuisUnDev"
}

# instance base de données RDS postgres variables
variable "db_allocated_storage" {
  description = "Allocated storage"
  default = 20
}
variable "db_storage_type" {
  description = "Storage type"
  default = "gp2"
}

variable "db_engine" {
  description = "Storage engine"
  default = "postgres"
}

variable "db_engine_version" {
  description = "Storage engine version"
  default = "11.5"
}

variable "db_instance_class" {
  description = "Storage instance class"
  default = "db.t2.micro"
}

variable "db_database_name" {
  description = "Storage database name"
  default = "postgres"
}

variable "db_database_username" {
  description = "Storage database name"
  default = "postgres"
}

variable "secret_db_database_password" {
  description = "Storage database secret password"
  default = "postgres"
}

variable "db_snapshot_identifier" {
  description = "Storage database snapshot identifier"
  default = "postgres"
}

コマンドを実行して変更を反映

Terraformの初期化 → ファイル検証 → アクションの計画(plan) → 変更の適用(apply)

> terraform init

Initializing the backend...

Initializing provider plugins...
- Checking for available provider plugins...
- Downloading plugin for provider "aws" (hashicorp/aws) 2.48.0...

Terraform has been successfully initialized!

構成ファイルの検証を行う

> terraform validate

Success! The configuration is valid.

Planを行う。インフラ構築の作成のみを行う

> terraform plan

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # aws_db_instance.default will be created
  # aws_instance.web will be created

Plan: 2 to add, 0 to change, 0 to destroy.

最後に、planを適用(apply)して、実際にインフラをクラウドに構築する

> terraform apply

aws_instance.web: Creating...
aws_db_instance.default: Creating...
aws_instance.web: Still creating... [10s elapsed]
aws_instance.web: Still creating... [30s elapsed]
aws_instance.web: Creation complete after 43s [id=i-0f285230749e69a67]
aws_db_instance.default: Still creating... [50s elapsed]
aws_db_instance.default: Still creating... [1m50s elapsed]
aws_db_instance.default: Still creating... [2m50s elapsed]
aws_db_instance.default: Still creating... [3m50s elapsed]
aws_db_instance.default: Still creating... [4m0s elapsed]
aws_db_instance.default: Creation complete after 4m8s [id=terraform-20200208064624729700000001]

Apply complete! Resources: 2 added, 0 changed, 0 destroyed.

構築したインフラを破棄する

> terraform destroy

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  - destroy

aws_instance.web: Destroying... [id=i-0f285230749e69a67]
aws_db_instance.default: Destroying... [id=terraform-20200208064624729700000001]
aws_instance.web: Destruction complete after 30s
aws_db_instance.default: Destruction complete after 50s

Destroy complete! Resources: 0 added, 0 changed, 2 destroyed.