A dictionary (key value pairs) can be defined in

• locals
• variable map (this article)

For example, let's say you have the following files on your Terraform server.

├── required_provider.tf
├── child (directory, child module)
│   ├── data.tf
│   ├── outputs.tf
│   ├── resources.tf
│   ├── variables.tf

Let's say variables.tf file has the following.

variable "protocols_and_ports_map" {
  type = map(string)
  default = {
    HTTP  = "80"
    HTTPS = "443"
  }
}

Here is an example of how you use loop through the dictionary in a resource.

resource "aws_lb_target_group" "target_groups" {

  for_each = var.protocols_and_ports_map

  name     = each.key
  port     = each.value
  protocol = each.key
  vpc_id   = data.aws_vpc.default_vpc.id

  tags = {
    Name = each.key
  }
}