File calling terraform module

module.tf

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

variable "environment" {}

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

variable "subnet_addresses" {
  default {
    a = "10.0.0.0/20"
    b = "10.0.16.0/20"
    d = "10.0.48.0/20"
    e = "10.0.64.0/20"
  }
}

variable "vpc_name" {}

resource "aws_vpc" "environment_vpc" {
  cidr_block = "${var.cidr_block}"
  enable_dns_support = true
  enable_dns_hostnames = true

  tags {
    Name = "${var.vpc_name}"
    environment = "${var.environment}"
  }
}

resource "aws_internet_gateway" "environment_gateway" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
}

resource "aws_route_table" "environment_route_table" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = "${aws_internet_gateway.environment_gateway.id}"
  }

  tags = {
    Name = "${var.vpc_name} Route Table"
    environment = "${var.environment}"
  }
}

resource "aws_main_route_table_association" "main_route_table_assoc" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
  route_table_id = "${aws_route_table.environment_route_table.id}"
}

resource "aws_subnet" "environment_subnet_a" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
  availability_zone = "${var.region}a"
  cidr_block = "${lookup(var.subnet_addresses, \"a\")}"
  map_public_ip_on_launch = true

  tags {
    Name = "${var.vpc_name} Subnet A"
    environment = "${var.environment}"
  }
}

resource "aws_subnet" "environment_subnet_b" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
  availability_zone = "${var.region}b"
  cidr_block = "${lookup(var.subnet_addresses, \"b\")}"
  map_public_ip_on_launch = true

  tags {
    Name = "${var.vpc_name} Subnet B"
    environment = "${var.environment}"
  }
}

resource "aws_subnet" "environment_subnet_d" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
  availability_zone = "${var.region}d"
  cidr_block = "${lookup(var.subnet_addresses, \"d\")}"
  map_public_ip_on_launch = true

  tags {
    Name = "${var.vpc_name} Subnet D"
    environment = "${var.environment}"
  }
}

resource "aws_subnet" "environment_subnet_e" {
  vpc_id = "${aws_vpc.environment_vpc.id}"
  availability_zone = "${var.region}e"
  cidr_block = "${lookup(var.subnet_addresses, \"e\")}"
  map_public_ip_on_launch = true

  tags {
    Name = "${var.vpc_name} Subnet E"
    environment = "${var.environment}"
  }
}

resource "aws_route_table_association" "environment_zone_a_assoc" {
  subnet_id = "${aws_subnet.environment_subnet_a.id}"
  route_table_id = "${aws_route_table.environment_route_table.id}"
}

resource "aws_route_table_association" "environment_zone_b_assoc" {
  subnet_id = "${aws_subnet.environment_subnet_b.id}"
  route_table_id = "${aws_route_table.environment_route_table.id}"
}

resource "aws_route_table_association" "environment_zone_d_assoc" {
  subnet_id = "${aws_subnet.environment_subnet_d.id}"
  route_table_id = "${aws_route_table.environment_route_table.id}"
}

resource "aws_route_table_association" "environment_zone_e_assoc" {
  subnet_id = "${aws_subnet.environment_subnet_e.id}"
  route_table_id = "${aws_route_table.environment_route_table.id}"
}

output "subnet_a_id" {
  value = "${aws_subnet.environment_subnet_a.id}"
}

output "subnet_b_id" {
  value = "${aws_subnet.environment_subnet_b.id}"
}

output "subnet_d_id" {
  value = "${aws_subnet.environment_subnet_d.id}"
}

output "subnet_e_id" {
  value = "${aws_subnet.environment_subnet_e.id}"
}

output "vpc_id" {
  value = "${aws_vpc.environment_vpc.id}"
}

Terraform.tf

variable "aws_access_key" {}
variable "aws_secret_key" {}
variable "aws_region" {}
variable "environment" {}
variable "vpc_cidr_block" {
  default = "10.255.0.0/16"
}
variable "vpc_name" {}
variable "vpc_subnet_addresses" {
  default = {
    a = "10.255.0.0/20"
    b = "10.255.16.0/20"
    d = "10.255.48.0/20"
    e = "10.255.64.0/20"
  }
}

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

module "new_vpc" {
  source = "../modules/vpcs/us_east_1"

  cidr_block = "${var.vpc_cidr_block}"
  environment = "${var.environment}"
  subnet_addresses = "${var.vpc_subnet_addresses}"
  vpc_name = "${var.vpc_name}"
}