Sample Terraform stack for EC2 and VPC

stack.tf

variable "aws_region" {
  default = "us-east-1"
}

variable "vpc_cidr" {
  default = "10.0.0.0/16"
}

variable "webSubnetCidr" {
  default = "10.0.1.0/24"
}

variable "appSubnetCidr" {
  default = "10.0.2.0/24"
}

variable "ami" {
  default = "ami-035be7bafff33b6b6"
}

variable "keypair" {
  default = "myKeyPair"
}

provider "aws" {
  region = "${var.aws_region}"
}

resource "aws_instance" "web" {
  ami           = "${var.ami}"
  instance_type = "t2.micro"
  subnet_id     = "${aws_subnet.web.id}"
  key_name      = "${var.keypair}"
  vpc_security_group_ids = ["${aws_security_group.web.id}"]
  associate_public_ip_address = true

  root_block_device {
    volume_size = "8"
    volume_type = "gp2"
  }
}

resource "aws_instance" "app" {
  ami           = "${var.ami}"
  instance_type = "t2.micro"
  subnet_id = "${aws_subnet.app.id}"
  key_name = "${var.keypair}"
  vpc_security_group_ids = ["${aws_security_group.app.id}"]
  associate_public_ip_address = false
  
  root_block_device {
    volume_size = "8"
    volume_type = "gp2"
  }
}

resource "aws_vpc" "default" {
  cidr_block = "${var.vpc_cidr}"
  enable_dns_hostnames = true
}

resource "aws_subnet" "web" {
  vpc_id = "${aws_vpc.default.id}"
  cidr_block = "${var.webSubnetCidr}"
}

resource "aws_subnet" "app" {
  vpc_id = "${aws_vpc.default.id}"
  cidr_block = "${var.appSubnetCidr}"
}

resource "aws_internet_gateway" "default" {
  vpc_id = "${aws_vpc.default.id}"
}

resource "aws_route_table" "public" {
  vpc_id = "${aws_vpc.default.id}"

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

resource "aws_route_table_association" "public" {
  subnet_id = "${aws_subnet.web.id}"
  route_table_id = "${aws_route_table.public.id}"
}

resource "aws_security_group" "web" {
  name = "web"
  vpc_id = "${aws_vpc.default.id}"

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

  ingress {
    from_port = 443
    to_port = 443
    protocol = "tcp"
    cidr_blocks = ["0.0.0.0/0"]
  }

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

  ingress {
    from_port = 22
    to_port = 22
    protocol = "tcp"
    cidr_blocks =  ["0.0.0.0/0"]
  }

  egress {
    from_port       = 0
    to_port         = 0
    protocol        = "-1"
    cidr_blocks     = ["${var.appSubnetCidr}"]
  }
}

resource "aws_security_group" "app" {
  name = "app"
  vpc_id = "${aws_vpc.default.id}"

  ingress {
    from_port = 80
    to_port = 80
    protocol = "tcp"
    cidr_blocks =  ["${var.webSubnetCidr}"]
  }

  ingress {
    from_port = -1
    to_port = -1
    protocol = "icmp"
    cidr_blocks =  ["${var.webSubnetCidr}"]
  }

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