做一些简单的联系，Deploy一些不同的Server。

Pre-condition

为了让Terraform和AWS工作，必须把AWS User的AWS_ACCESS_KEY_ID和AWS_SECRET_ACCESS_KEY加到环境变量。

1 2	set AWS_ACCESS_KEY_ID=(your access key id) set AWS_SECRET_ACCESS_KEY=(your secret access key)

Single Server

创建Config文件

provider "aws" {
	region = "us-east-1"
}

resource "aws_instance" "yongfeiuall" {
	ami = "ami-1853ac65"
	instance_type = "t2.micro"
	tags{
	Name = "simple single server"
	}
}

执行命令terraform plan，terraform apply
验证成功

Single Web Server

创建Config文件

provider "aws" {
	region = "ap-northeast-1"
}

resource "aws_instance" "yongfeiuall" {
	ami = "ami-28ddc154"
	instance_type = "t2.micro"
	
	tags{
	Name = "simple web server"
	}
	user_data = <<-EOF
				#!/bin/bash
				yum update -y
				yum install -y httpd
				service httpd start
				echo '<html><h1> single web server from terraform </h1></html>' > /var/www/html/index.html
				EOF
	
	vpc_security_group_ids = ["${aws_security_group.http.id}"]
}

resource "aws_security_group" "http" {
	name = "yonfeiuall_single_web"

	# HTTP access from anywhere
	ingress {
		from_port   = 80
		to_port     = 80
		protocol    = "tcp"
		cidr_blocks = ["0.0.0.0/0"]
	}
	  
	# Outbound internet access
	egress {
		from_port   = 0
		to_port     = 0
		protocol    = "-1"
		cidr_blocks = ["0.0.0.0/0"]
	}
}

说明：

AWS默认不允许任何Incoming和Outcoming，我们要建一个Security Group（要同时有Inbound和Outbound）
把SG要添加到EC2上，用到SG的ID,Terraform里，用"${TYPE.NAME.ATTRIBUTE}"语法来引用其他Resources的Attribute
The <<-EOF and EOF are allows you to create multiline strings without having to insert newline characters all over the place.

执行命令terraform plan，terraform apply

验证成功

1 2	yongfeiuall@automation:~$ curl http://13.113.195.209 <html><h1> single web server from terraform </h1></html>

用Browser打开，可以看到。

Configurable Web Server

为了更好的管理，Terraform允许定义Input变量：

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variable "NAME" {
[CONFIG ...]
}

The body of the variable declaration can contain three parameters, all of them
optional:

description
Use this parameter to document how a variable is used.
default
There are a number of ways to provide a value for the variable.

type
Must be one of “string”, “list”, or “map”.
E.g.,

variable "list_example" {
description = "An example of a list in Terraform"
type = "list"
default = [1, 2, 3]
}

用下面的方式来读取变量"${var.VARIABLE_NAME}"。

同时，Terraform还允许定义Output变量：

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output "NAME" {
value = VALUE
}

可以返回创建Instance后你想获得的一些属性，例如：

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output "public_ip" {
value = "${aws_instance.example.public_ip}"
}

创建Config文件

variable "server_port" {
	description = "The port the server will use for HTTP requests"
	default = 80
}
output "public_ip" {
value = "${aws_instance.yongfeiuall.public_ip}"
}

provider "aws" {
	region = "ap-northeast-1"
}

resource "aws_instance" "yongfeiuall" {
	ami = "ami-28ddc154"
	instance_type = "t2.micro"
	
	tags{
	Name = "configurable web server"
	}
	user_data = <<-EOF
				#!/bin/bash
				yum update -y
				yum install -y httpd
				service httpd start
				echo '<html><h1> configurable web server from terraform </h1></html>' > /var/www/html/index.html
				EOF
	
	vpc_security_group_ids = ["${aws_security_group.http.id}"]
}

resource "aws_security_group" "http" {
	name = "yonfeiuall_single_web"

	# HTTP access from anywhere
	ingress {
		from_port   = "${var.server_port}"
		to_port     = "${var.server_port}"
		protocol    = "tcp"
		cidr_blocks = ["0.0.0.0/0"]
	}
	  
	# Outbound internet access
	egress {
		from_port   = 0
		to_port     = 0
		protocol    = "-1"
		cidr_blocks = ["0.0.0.0/0"]
	}
}

执行命令terraform plan，terraform apply
验证成功