aws-creds.tfvars.example

access_key = ""
secret_key = ""

main.tf

provider "aws" {
  alias = "west"

  access_key = "${var.access_key}"
  secret_key = "${var.secret_key}"

  region = "us-west-2"
}

module "vpc" {
  source = "./modules/vpc"

  name = "derp-vpc"
  cidr = "10.1.0.0/16"

  public_subnets = "10.1.0.0/19,10.1.64.0/19,10.1.128.0/19"
  private_subnets = "10.1.32.0/19,10.1.96.0/19,10.1.160.0/19"
  az_names = "us-west-2a,us-west-2b,us-west-2c"

  aws_provider = "aws.west"

  nat_instance_size = "t2.small"
  nat_ami = "ami-290f4119"
}

module-main.tf

resource "aws_vpc" "module" {
  provider = "${var.aws_provider}"
  cidr_block = "${var.cidr}"

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

resource "aws_internet_gateway" "module" {
  provider = "${var.aws_provider}"
  vpc_id = "${aws_vpc.module.id}"
}

resource "aws_route_table" "public" {
  provider = "${var.aws_provider}"
  vpc_id = "${aws_vpc.module.id}"

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

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

resource "aws_subnet" "public" {
  provider = "${var.aws_provider}"
  count = "${length(split(",", var.public_subnets))}"

  vpc_id = "${aws_vpc.module.id}"
  cidr_block = "${element(split(",", var.public_subnets), count.index)}"
  availability_zone = "${element(split(",", var.az_names), count.index)}"

  map_public_ip_on_launch = true

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

resource "aws_route_table_association" "public" {
  provider = "${var.aws_provider}"
  count = "${length(split(",", var.public_subnets))}"

  subnet_id = "${element(aws_subnet.public.*.id, count.index)}"
  route_table_id = "${aws_route_table.public.id}"
}

resource "aws_instance" "nat" {
  provider = "${var.aws_provider}"
  count = "${length(split(",", var.private_subnets))}"

  ami = "${var.nat_ami}"
  instance_type = "${var.nat_instance_type}"

  source_dest_check = false

  subnet_id = "${element(aws_subnet.public.*.id, count.index)}"
  security_groups = ["${split(",", var.security_groups)}"]

  tags {
    Name = "${var.name}-#{aws_subnet.public.*.availability_zone, count.index}-nat"
  }
}

resource "aws_route_table" "private" {
  provider = "${var.aws_provider}"
  count = "${length(split(",", var.private_subnets))}"

  vpc_id = "${aws_vpc.module.id}"

  route {
    cidr_block = "0.0.0.0/0"
    gateway_id = "${element(aws_instance.nat.*.id, count.index)}"
  }

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

resource "aws_subnet" "private" {
  provider = "${var.aws_provider}"
  count = "${length(split(",", var.private_subnets))}"

  vpc_id = "${aws_vpc.module.id}"
  cidr_block = "${element(split(",", var.private_subnets), count.index)}"
  availability_zone = "${element(split(",", var.az_names), count.index)}"

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

resource "aws_route_table_association" "private" {
  provider = "${var.aws_provider}"
  count = "${length(split(",", var.private_subnets))}"

  subnet_id = "${element(aws_subnet.private.*.id, count.index)}"

  route_table_id = "${aws_route_table.private.id}"
}

module-variables.tf

variable "aws_provider" { }
variable "name" { }
variable "cidr" { }

variable "public_subnets" { }
variable "private_subnets" { }
variable "az_names" { }

variable "nat_instance_type" { }
variable "nat_ami" { }

output

 ~  workspace  infrastructure  terraform  master +  $  terraform plan -var-file aws-creds.tfvars
There are warnings and/or errors related to your configuration. Please
fix these before continuing.

Errors:

  * 1 error(s) occurred:

* module vpc.root: 10 error(s) occurred:

* resource 'aws_instance.nat' config: unknown variable referenced: 'security_groups'. define it with 'variable' blocks
* aws_subnet.public: resource depends on non-configured provider '${var.aws_provider}'
* aws_subnet.private: resource depends on non-configured provider '${var.aws_provider}'
* aws_route_table.public: resource depends on non-configured provider '${var.aws_provider}'
* aws_internet_gateway.module: resource depends on non-configured provider '${var.aws_provider}'
* aws_route_table_association.public: resource depends on non-configured provider '${var.aws_provider}'
* aws_instance.nat: resource depends on non-configured provider '${var.aws_provider}'
* aws_route_table.private: resource depends on non-configured provider '${var.aws_provider}'
* aws_route_table_association.private: resource depends on non-configured provider '${var.aws_provider}'
* aws_vpc.module: resource depends on non-configured provider '${var.aws_provider}'

variables.tf

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