Terraform - Multiple accounts with multiple environments (regions) - amazon-web-services

Question

I am developing the infrastructure (IaC) I want to have in AWS with Terraform. To test, I am using an EC2 instance.
This code has to be able to be deployed across multiple accounts and **multiple regions (environments) per developer **. This is an example:
account-999
developer1: us-east-2
developer2: us-west-1
developerN: us-east-1
account-666:
Staging: us-east-1
Production: eu-west-2
I've created two .tfvars variables, account-999.env.tfvars and account-666.env.tfvars with the following content:
profile="account-999" and profile="account-666" respectively
This is my main.tf which contains the aws provider with the EC2 instance:
provider "aws" {
version = "~> 2.0"
region = "us-east-1"
profile = var.profile
}
data "aws_ami" "ubuntu" {
most_recent = true
filter {
name = "name"
values = ["ubuntu/images/hvm-ssd/ubuntu-focal-20.04-amd64-server-*"]
}
filter {
name = "virtualization-type"
values = ["hvm"]
}
owners = ["099720109477"]
}
resource "aws_instance" "web" {
ami = data.aws_ami.ubuntu.id
instance_type = "t3.micro"
tags = {
Name = "HelloWorld"
}
}
And the variable.tf file:
variable "profile" {
type=string
}
variable "region" {
description = "Region by developer"
type = map
default = {
developer1 = "us-west-2"
developer2 = "us-east-2"
developerN = "ap-southeast-1"
}
}
But I'm not sure if I'm managing it well. For example, the region variable only contains the values of the account-999 account. How can I solve that?
On the other hand, with this structure, would it be possible to implement modules?

Answer 1

You could use a provider alias to accomplish this. More info about provider aliases can be found here.
provider "aws" {
region = "us-east-1"
}
provider "aws" {
alias = "west"
region = "us-west-2"
}
resource "aws_instance" "foo" {
provider = aws.west
# ...
}
Another way to look at is, is by using terraform workspaces. Here is an example:
terraform workspace new account-999
terraform workspace new account-666
Then this is an example of your aws credentials file:
[account-999]
aws_access_key_id=xxx
aws_secret_access_key=xxx
[account-666]
aws_access_key_id=xxx
aws_secret_access_key=xxx
A reference to that account can be used within the provider block:
provider "aws" {
region = "us-east-1"
profile = "${terraform.workspace}"
}
You could even combine both methods!