Terraform: Conditional creation of a resource based on a variable in .tfvars

Question

I have resources defined in .tf files that are generic to several applications. I populate many of the fields via a .tfvars file. I need to omit some of the resources entirely based on variables in the .tfvars.

For example if I have a resource like:

resource "cloudflare_record" "record" {
  zone_id = "${data.cloudflare_zones.domain.zones[0].id}"
  name    = "${var.subdomain}"
  value   = "${var.origin_server}"
  type    = "CNAME"
  ttl     = 1
  proxied = true
}

But then I declare something like cloudflare = false in my .tfvars file I'd like to be able to do something like this:

if var.cloudflare {
  resource "cloudflare_record" "record" {
    zone_id = "${data.cloudflare_zones.domain.zones[0].id}"
    name    = "${var.subdomain}"
    value   = "${var.origin_server}"
    type    = "CNAME"
    ttl     = 1
    proxied = true
 }
}

I've looked at dynamic blocks but that looks like you can only use those to edit fields and blocks within a resource. I need to be able to ignore an entire resource.

Answer 1

Add a count parameter with a ternary conditional using the variable declared in .tfvars like this:

resource "cloudflare_record" "record" {
  count = var.cloudflare ? 1 : 0
  zone_id = "${data.cloudflare_zones.domain.zones[0].id}"
  name    = "${var.subdomain}"
  value   = "${var.origin_server}"
  type    = "CNAME"
  ttl     = 1
  proxied = true
}

In this example var.cloudflare is a boolean declared in the .tfvars file. If it is true a count of 1 record will be created. If it is false a count of 0 record will be created.

After the count apply the resource becomes a group, so later in the reference use 0-index of the group:

cloudflare_record.record[0].some_field

Answer 2

An issue i'm seeing this with is if the resource your trying to create is already using a for_each then you can't use both count and for_each in the resource. I'm still trying to find an answer on this will update if I find something better.