Terraform skip null for_each - amazon-web-services

Question

I am setting tags to AMI. I have ubuntu and EKS AMI, where EKS AMI needs to be set with k8s version, containerd etc which are not required for other OS. I have declared all variables that are EKS specific to default to null in an assumption that they will skipped while I run for_each but it errors out. Here is the code and error.
locals {
tags = {
docker_version = var.docker_version
kubernetes = var.k8s_version
cni_plugin_version = var.cni_plugin_version
containerd_version = var.containerd_version
target = var.target
source_ami_id = var.source_ami_id
Release = var.ami_release-version
Description = var.ami_description
Name = var.ami_name
Creator = var.creator
}
data "aws_ami" "ami_image" {
most_recent = true
owners = ["xxxxxxxx"]
name_regex = var.ami_regex
}
output "ami_id" {
value = data.aws_ami.ami_image.id
}
output "ami_arn" {
value = data.aws_ami.ami_image.arn
}
output "ami_name" {
value = data.aws_ami.ami_image.name
}
resource "aws_ec2_tag" "ami-taggging" {
resource_id = data.aws_ami.ami_image.id
for_each = local.tags
key = each.key
value = each.value
}
Error when values are null:
Error: Missing required argument
on main.tf line 41, in resource "aws_ec2_tag" "ami-tagging":
41: value = each.value
Is there a way to skip or gracefully move to next record if the value is null.

Answer 1

Assuming that default_tags (not shown in your question) is similar to your local.tag, you could do the following:
resource "aws_ec2_tag" "ami-taggging" {
resource_id = data.aws_ami.ami_image.id
for_each = {for k,v in local.tags: k => v if v != null}
key = each.key
value = each.value
}
The solution uses for expression. Basically, it takes your original local.tags and creates new temporary map that will be used in the for_each. The new map will have same keys and values (k=>v) except those that don't meet the if condition.