首先

本文介绍了如何使用Terraform的导入功能，将手动创建的现有VPC和子网管理到Terraform中的步骤。

前提条件

假设Terraform已被安装。

$ terraform --version
Terraform v0.11.8

步驟

请为工作目录准备好各个设定文件。
（请根据现有环境相应地调整 variables.tf 文件中各个变量的值以及 NameTag 的存在与否。）

$ tree terraform/
terraform/
├── aws.tf
├── terraform.tfvars
├── variables.tf
└── vpc.tf

aws_access_key = "アクセスキー"
aws_secret_key = "シークレットキー"
aws_region = "ap-northeast-1"

provider "aws" {
  access_key = "${var.aws_access_key}"
  secret_key = "${var.aws_secret_key}"
  region     = "${var.aws_region}"
  version    = "~> 1.0"
}

## AWS
variable "aws_access_key" {}

variable "aws_secret_key" {}

variable "aws_region" {
  default = "ap-northeast-1"
}

data "aws_caller_identity" "self" {}

## VPC CIDR
variable "vpc_cidr" {
  default = "10.1.0.0/16"
}

## VPC Name Tag
variable "vpc_name_tag" {
  default = "terraform-import-vpc"
}

## Subnet
variable "subnet_cidr" {
  type = "map"

  default = {
    public-a  = "10.1.10.0/24"
    public-c  = "10.1.20.0/24"
    private-a = "10.1.100.0/24"
    private-c = "10.1.200.0/24"
  }
}

## Subnet Name Tag
variable "subnet_name_tag" {
  type = "map"

  default = {
    public-a  = "terraform-import-public-subnet-a"
    public-c  = "terraform-import-public-subnet-c"
    private-a = "terraform-import-private-subnet-a"
    private-c = "terraform-import-private-subnet-c"
  }
}

# VPC
resource "aws_vpc" "vpc" {
  cidr_block = "${var.vpc_cidr}"

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

# Subnet
resource "aws_subnet" "public-a" {
  vpc_id            = "${aws_vpc.vpc.id}"
  cidr_block        = "${var.subnet_cidr["public-a"]}"
  availability_zone = "ap-northeast-1a"

  tags {
    Name = "${var.subnet_name_tag["public-a"]}"
  }
}

resource "aws_subnet" "public-c" {
  vpc_id            = "${aws_vpc.vpc.id}"
  cidr_block        = "${var.subnet_cidr["public-c"]}"
  availability_zone = "ap-northeast-1c"

  tags {
    Name = "${var.subnet_name_tag["public-c"]}"
  }
}

resource "aws_subnet" "private-a" {
  vpc_id            = "${aws_vpc.vpc.id}"
  cidr_block        = "${var.subnet_cidr["private-a"]}"
  availability_zone = "ap-northeast-1a"

  tags {
    Name = "${var.subnet_name_tag["private-a"]}"
  }
}

resource "aws_subnet" "private-c" {
  vpc_id            = "${aws_vpc.vpc.id}"
  cidr_block        = "${var.subnet_cidr["private-c"]}"
  availability_zone = "ap-northeast-1c"

  tags {
    Name = "${var.subnet_name_tag["private-c"]}"
  }
}

使用下面的命令，对Terraform的工作目录进行初始化。

$ terraform init

Initializing provider plugins...
- Checking for available provider plugins on https://releases.hashicorp.com...
- Downloading plugin for provider "aws" (1.58.0)...

Terraform has been successfully initialized!

请使用以下命令来导入现有的VPC。

terraform import aws_vpc.vpc [VPCのID]

请使用以下命令导入现有子网。

terraform import aws_subnet.public-a [Public Subnet A の ID]
terraform import aws_subnet.public-c [Public Subnet C の ID]
terraform import aws_subnet.private-a [Private Subnet A の ID]
terraform import aws_subnet.private-c [Private Subnet C の ID]

将会生成 terraform.tfstate 文件。

$ tree terraform/
terraform/
├── aws.tf
├── terraform.tfstate
├── terraform.tfstate.backup
├── terraform.tfvars
├── variables.tf
└── vpc.tf

通过以下命令，确认是否存在差异，若显示以下消息，则表示完成。

$ terraform plan

No changes. Infrastructure is up-to-date.