Terraform Multiple Provider issue - terraform

Question

I am following the documentation here running Terraform v0.14.10 -> https://www.terraform.io/docs/language/modules/develop/providers.html
My config is as follows:
variables.tf
terraform {
backend "remote" {
organization = "the-xxxx"
workspaces {
prefix = "non-prod-"
}
}
required_providers {
aws = {
source = "hashicorp/aws"
version = "3.32.0"
}
}
}
provider "aws" {
}
provider "aws" {
alias = "core_db_middleware"
profile = "core_db_middleware"
}
provider "aws" {
alias = "us-east-1"
region = "us-east-1"
}
in main.tf where I call my module:
module "vpc" {
source = "../modules/infrastructure/shared/aws/vpc"
providers = {
aws.core_db_middleware = aws.core_db_middleware
}
class_b_block = var.class_b_block
platform_name = var.platform_name
core_platform_aws_account_id = var.core_platform_aws_account_id
core_platform_vpc_id = var.core_platform_vpc_id
core_platform_region = var.core_platform_region
core_platform_cidr_range = var.core_platform_cidr_range
}
Then in the "vpc" module variables.tf I have:
provider "aws" {}
provider "aws" {
alias = "core_db_middleware"
}
data "aws_caller_identity" "requester" {
provider = aws.core_db_middleware
}
data "aws_region" "requester" {
provider = aws.core_db_middleware
}
When I run plan on terraform it keeps giving me the aws account ID of the default provider even though I have:
data "aws_caller_identity" "requester" {
provider = aws.core_db_middleware
}
and use it like so:
resource "aws_vpc_peering_connection" "core_db_middleware_requester" {
peer_owner_id = data.aws_caller_identity.requester.account_id
peer_vpc_id = "vpc-xxxxxxxxxxxxxx"
vpc_id = aws_vpc.main.id
peer_region = data.aws_region.requester.name
auto_accept = false
tags = {
Name = "VPC Peering between ${var.platform_name} and core_db_middleware"
}
}
I tried adding the configuration_aliases = [ aws.core_db_middleware ] to my main.tf in my root directory as described in the official documentation and in the "vpc" module directory but I get the below error when in my root main:
Error: Invalid required_providers object
on variables.tf line 9, in terraform:
9: aws = {
10: source = "hashicorp/aws"
11: version = "3.32.0"
12: configuration_aliases = [ aws.core_db_middleware ]
13: }
required_providers objects can only contain "version" and "source" attributes.
To configure a provider, use a "provider" block.
Error: Variables not allowed
on variables.tf line 12, in terraform:
12: configuration_aliases = [ aws.core_db_middleware ]
Variables may not be used here.
and the below error when I place it in the "vpc" module:
Error: Variables not allowed
On ../modules/infrastructure/shared/aws/vpc/variables.tf line 33: Variables
may not be used here.
Error: Variables not allowed
On ../modules/infrastructure/shared/aws/vpc/variables.tf line 33: Variables
may not be used here.
Error: Variables not allowed
On ../modules/infrastructure/shared/aws/vpc/variables.tf line 33: Variables
may not be used here.
Error: Variables not allowed
On ../modules/infrastructure/shared/aws/vpc/variables.tf line 33: Variables
may not be used here.
I cannot figure out where I am going wrong :( I do also have my default provider aws environment variables set in the pipeline environment e.g
AWS_ACCESS_KEY_ID: $xxxxxxxxxxx_AWS_ACCESS_KEY_ID
AWS_SECRET_ACCESS_KEY: $xxxxxxxxxx_AWS_SECRET_ACCESS_KEY
AWS_DEFAULT_REGION: 'ap-southeast-2'