Terraform: Local list of maps iteration with for_each and conditionals

Question

I want to define a list of maps inside a variable so I can use for_each on multiple resources with conditionals based on the key values.

For example I have this locals.tf file where I define the list of maps

locals {
  networking = [
    {
      name = "first"
      domain = "first.${local.dns_name}"
      port = 8080
      group = "eighties"

    },
    {
      name = "second"
      domain = "second.${local.dns_name}"
      port = 8081
      group = "eighties"
    },
    {
      name = "third"
      domain = "third.${local.dns_name}"
      port = 9090
      group = "nineties"
    },
    {
      name = "fourth"
      port = 9091
      group = "nineties"
    }
  ]
}

In my other file, I can loop through the list of maps with for_each and for arguments:

resource "google_dns_record_set" "dns_records" {
  for_each     = { 
    for k in local.networking: k.domain => k
    if k.domain != null
  }
  name         = each.value.domain
  type         = "A"
  ttl          = 300
  managed_zone = var.managed_zone
  project      = var.dns_project
  rrdatas      = [google_compute_global_address.default-forwarding-address.address]
}

Given this setup, I have 2 different situations that I might discuss:

1. Since the domain key doesn't exists for the fourth map, Terraform just stops.

Is it possible to skip the resource creations if domain does not exist in the fourth map? Or simply skip the errors.

Error: Unsupported attribute on dns-record.tf line 4, in resource "google_dns_record_set" "dns_records": 4: if k.domain.= null This object does not have an attribute named "domain".

2. If I change the k.domain values for k.group and the conditional to be something like k.group == "eighties" so I can target a specific group, I receive this duplication error.

Two different items produced the key "eighties" in this 'for' expression. If duplicates are expected, use the ellipsis (...) after the value expression to enable grouping by key.

Are this errors manageable with the current setup or should I drop the list of maps idea?

Answer 1

You can check if the domain exist as follows:

{ 
    for k in local.networking: k.domain => k
    if contains(keys(k), "domain")
}