Terraform build EC2 instance

#Introduction

In this tutorial, How to build a simple environment with one EC2 instance base AWS. Terraform build EC2 instance. This time, I created as follows.

VPC
Internet Gateway
Subnet
Route Table
Security Group
EC2

My Environment for Terraform build EC2 instance

OS Window
Terraform

To install Terraform, By referring to the following.

Installing Terraform –Terraform by HashiCorp

If you are on Windows, you can install it as follows.

choco install terraform
terraform -help

Create a template file

First of all, Create a subdirectory and a Terraform template file in it. The name of the template file is arbitrary, but the extensions are *.tf

$ mkdir terraform-aws
$ cd terraform-aws
$ touch main.tf

Terraform Provider settings

We use the provided settings AWS. Terraform supports multiple providers.

provider "aws" {
    access_key = "ACCESS_KEY_HERE"
    secret_key = "SECRET_KEY_HERE"
    region = "us-west-2"
}

Credential information

Use of Terraform variables

variable "access_key" {}
variable "secret_key" {}

provider "aws" {
    access_key = "${var.access_key}"
    secret_key = "${var.secret_key}"
    region = "us-west-2"
}

Assigning a value to a variable

There are three ways to assign a value to a variable.

1.Terraform command

$ terraform apply \
-var 'access_key=AXXXXXXXXXXXXXXXXXXXXXX' \
-var 'secret_key=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'

2.Value in the environment variable

$ export TF_VAR_access_key="AXXXXXXXXXXXXXXXXXXXXX"
$ export TF_VAR_secret_key="XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"

3.Pass the value in a file

For example, the content terraform.tfvars file.

aws_access_key = "AXXXXXXXXXXXXXXXXXXXXX"
aws_secret_key = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"

How to set Default value of variable

For example, We can set default values for variables.

variable "aws_access_key" {}
variable "aws_secret_key" {}
variable "region" {
    default = "us-west-2"
}

provider "aws" {
    access_key = "${var.aws_access_key}"
    secret_key = "${var.aws_secret_key}"
    region = "${var.region}"
}

Provider: AWS –Terraform by HashiCorp

Terraform Resource settings.

In Terraform the resource type is aws_* predefined. Example aws_vpc a VPC, EC2 is aws_instance. Each AWS resource in the format of item name = value. Example the VPC settings.

resource "aws_vpc" "myVPC" {
    cidr_block = "10.1.0.0/16"
    instance_tenancy = "default"
    enable_dns_support = "true"
    enable_dns_hostnames = "false"
    tags = {
      Name = "myVPC"
    }
}

Refer other resources

Internet Gateway settings.

resource "aws_vpc" "myVPC" {
    cidr_block = "10.1.0.0/16"
    instance_tenancy = "default"
    enable_dns_support = "true"
    enable_dns_hostnames = "false"
    tags {
      Name = "myVPC"
    }
}

resource "aws_internet_gateway" "myGW" {
    vpc_id = "${aws_vpc.myVPC.id}"
}

Dependencies between resources

For example, set up a dependency between the VPC and Internet Gateway.

resource "aws_vpc" "myVPC" {
    cidr_block = "10.1.0.0/16"
    instance_tenancy = "default"
    enable_dns_support = "true"
    enable_dns_hostnames = "false"
    tags {
      Name = "myVPC"
    }
}

resource "aws_internet_gateway" "myGW" {
    vpc_id = "${aws_vpc.myVPC.id}"
    depends_on = "${aws_vpc.myVPC}"
}

We mentioned above how to set the default value for a variable. we use of Map as follows

variable "images" {
    default = {
        us-east-1 = "ami-1ecae776"
        us-west-2 = "ami-e7527ed7"
        us-west-1 = "ami-d114f295"
    }
}

The values of variables defined as var.images.us-east-1

Output on the console

output "public ip of aws-test" {
  value = "${aws_instance.aws-test.public_ip}"
}