foobar.tf

variable "name" {}
variable "region" {
  default = "eu-west-1"
}

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

variable "public_subnets" {
  type = "map"
  default = {
    # (254 hosts each)
    "a" = "10.0.0.0/24"
    "b" = "10.0.1.0/24"
    "c" = "10.0.2.0/24"
    "d" = "10.0.3.0/24"
  }
}

variable "private_subnets" {
  type = "map"
  default = {
    # (4094 hosts each)
    "a" = "10.16.0.0/20"
    "b" = "10.16.16.0/20"
    "c" = "10.16.32.0/20"
    "d" = "10.16.48.0/20"
  }
}

data "aws_availability_zones" "available" {}

resource "aws_vpc" "default" {
  # 10.0.0.1 - 10.15.255.254 (1,048,574 hosts)
  cidr_block = "10.0.0.0/16"

  enable_dns_support = true
  enable_dns_hostnames = true

  enable_classiclink_dns_support = false
  enable_classiclink = false
  assign_generated_ipv6_cidr_block = false

  tags {
    Name = "${var.name}-vpc"
  }
}

resource "aws_subnet" "public" {
  count = "${length(data.aws_availability_zones.available.names)}"

  availability_zone = "${var.region}${element(keys(var.public_subnets), count.index)}"

  vpc_id = "${aws_vpc.default.id}"
  cidr_block = "${element(values(var.public_subnets), count.index)}"

  tags {
    Name = "${var.name}-public-${var.region}-${element(keys(var.public_subnets), count.index)}"
  }
}

resource "aws_subnet" "private" {
  count = "${length(data.aws_availability_zones.available.names)}"

  availability_zone = "${var.region}${element(keys(var.private_subnets), count.index)}"

  vpc_id = "${aws_vpc.default.id}"
  cidr_block = "${element(values(var.private_subnets), count.index)}"

  tags {
    Name = "${var.name}-private-${var.region}-${element(keys(var.private_subnets), count.index)}"
  }
}