Terraform lookup AWS region - amazon-web-services

Question

I have the following code in my main.tf file:
provider "aws" {
access_key = "${var.aws_access_key}"
secret_key = "${var.aws_secret_key}"
region = "us-east-1"
alias = "us-east-1"
}
provider "aws" {
access_key = "${var.aws_access_key}"
secret_key = "${var.aws_secret_key}"
region = "us-west-1"
alias = "us-west-1"
}
module "us-east_vpc" {
source = "./setup-networking"
providers = {
"aws.region" = "aws.us-east-1"
}
}
module "us-west_vpc" {
source = "./setup-networking"
providers = {
"aws.region" = "aws.us-west-1"
}
}
And then in my modules file I have:
provider "aws" {
alias = "region"
}
resource "aws_vpc" "default" {
provider = "aws.region"
cidr_block = "${lookup(var.vpc_cidr, ${aws.region.region})}"
enable_dns_hostnames = true
tags {
Name = "AWS VPC"
}
}
resource "aws_internet_gateway" "default" {
provider = "aws.region"
vpc_id = "${aws_vpc.default.id}"
}
resource "aws_subnet" "default" {
provider = "aws.region"
vpc_id = "${aws_vpc.default.id}"
cidr_block = "${lookup(var.subnet_cidr, ${aws.region.region})}"
availability_zone = "aws.region"
tags {
Name = "AWS Subnet"
}
}
resource "aws_route_table" "default" {
provider = "aws.region"
vpc_id = "${aws_vpc.default.id}"
route {
cidr_block = "0.0.0.0/0"
gateway_id = "${aws_internet_gateway.default.id}"
}
tags {
Name = "Main Gateway"
}
}
As you can see in the modules file code I am trying to do a lookup to find the VPC CIDR mask and the subnet CIDR mask from map variables.
The trouble is that I can't seem to sort out how to get the region to be used as a lookup value.
If I hard code these values:
cidr_block = "10.10.0.0/16"
cidr_block = "10.10.10.0/24"
The script works as expected but I don't want to hard code the values.
Can someone with more Terraform experience help me understand how I can properly reference the region to lookup the correct value?

Answer 1

I was looking for the same answer for a different problem. I wanted to get the region for a name of a role, I was able to get the info by doing this:
1.- Create a file like data.tf and add this info:
data "aws_region" "current" {}
2.- Get the info from the data by calling this variable in any TF file:
name = "${var.vpc-name}-${data.aws_region.current.name}-Bastion-Role"
This way it will get the region where you are executing the code, and you don't have to mess with the provider.tf file.

Answer 2

You can get the region that's currently in use by the provider by using the aws_region data source.
So in your case you could do something like this:
provider "aws" {
alias = "region"
}
data "aws_region" "current" {
provider = "aws.region"
}
resource "aws_vpc" "default" {
provider = "aws.region"
cidr_block = "${lookup(var.vpc_cidr, ${data.aws_region.current.name})}"
enable_dns_hostnames = true
tags {
Name = "AWS VPC"
}
}
...

Answer 3

provider "aws" {
alias = "region"
}
data "aws_region" "current" {
provider = "aws.region"
}
data "aws_availability_zone" "current" {
provider = "aws.region"
name = "${data.aws_region.current.name}a"
}
resource "aws_vpc" "default" {
provider = "aws.region"
cidr_block = "${lookup(var.vpc_cidr, data.aws_availability_zone.current.name)}"
enable_dns_hostnames = true
tags {
Name = "${data.aws_region.current.name} Security VPC1"
Region = "${data.aws_region.current.name}"
Account = "Security"
}
}