Error Using Variable as a Tag in Terraform

Question

I have a question about tags in Terrafrom. I have this variables, and I'd like to use the Transit variable description name as a tag in my main.tf file. How do I go about it?

#VPC CIDRs
variable "All_VPCs" {
  type = map(any)
  default = {
    Dev_VPC = {
      ip = "10.0.3.0/24"
      instance_tenancy = "default"
    }
    Transit_VPC = {
      ip = "10.0.4.0/23"
      instance_tenancy = "default"
      description = "Transit_VPC"
    }
  }
}

I used this, but it didn't work.

resource "aws_internet_gateway" "Transit_Internet_Gateway" {
  vpc_id = var.All_VPCs.Transit_VPC

tags = {
    Name = "${var.All_VPCs.Transit_VPC.description}" + " Internet_Gateway"
  }

Answer 1

You can't concatenate strings in Terraform with a + operator. The correct method of doing this is to use string interpolation (which you are already partially doing):

tags = {
    Name = "${var.All_VPCs.Transit_VPC.description} Internet_Gateway"
  }