How to create a Terraform with if, else, elsif statement?

Question

I'm setting up a terraform module to create an aurora cluster.
I need to have an option for cross region replication so i need to decide the region of the replica in relation to the source region.
Is there any way to do a multiple option conditional in terraform?

Answer 1

This is one way using the coalesce() function:

locals{
  prod = "${var.environment == "PROD" ? "east" : ""}"
  prod2 = "${var.environment == "PROD2" ? "west2" : ""}"
  nonprod = "${var.environment != "PROD" && var.environment != "PROD2" ? "west" : ""}"
  region = "${coalesce(local.prod,local.prod2, local.nonprod)}"
}

Answer 2

locals {
  test = "${ condition ? value : (elif-condition ? elif-value : else-value)}"
}

For a more literal "if-elif-else" approach you can embed the if short hand with other ones to produce a similar effect. If you're use case is also inside a for loop, you can do that as well:

locals {
  test = {
    for i in list : 
      key => "${ condition ? value : (elif-condition ? elif-value : else-value)}"
  }
}

Will work in any situation where you would use the "${}" syntax