Terraform. How to identify element (key) using for_each - amazon-ec2

Question

I'm building AWS Network LB with target groups. And I stuck on aws_lb_listener adding several target_group_arn in several http_tcp_listeners
I.e. I have two aws_lb_target_group for 80 and 443 ports and two http_tcp_listeners for these same ports.
But I have got this error message:
in resource "aws_lb_listener" "frontend_http_tcp":
│ 172: target_group_arn = each.value.arn
│ ├────────────────
│ │ each.value is map of string with 4 elements
│
│ This map does not have an element with the key "arn".
variable "aws_lb_target_group" {
description = "aws_lb_target_group"
type = map(any)
default = {
http = {
name = "http"
target_type = "instance"
port = 80
protocol = "TCP"
protocol_version = "HTTP1"
type = "source_ip"
enabled = false
path_health_check = "/health.html"
matcher_health_check = "200" # has to be HTTP 200 or fails
},
https = {
name = "https"
target_type = "instance"
port = 443
protocol = "TCP"
protocol_version = "HTTP2"
type = "source_ip"
enabled = false
path_health_check = "/health.html"
matcher_health_check = "200" # has to be HTTP 200 or fails
}
}
}
variable "http_tcp_listeners" {
description = "aws_lb_listener"
type = map(any)
default = {
http = {
port = "80"
protocol = "TCP"
action_type = "forward"
alpn_policy = "HTTP1Only"
},
https = {
port = "443"
protocol = "TCP"
action_type = "forward"
certificate_arn = "data.terraform_remote_state.acm.outputs.acm_certificate_arn"
alpn_policy = "HTTP2Preferred"
}
}
}
resource "aws_lb_target_group" "main" {
for_each = var.aws_lb_target_group
name = "test-group-${random_pet.this.id}-${each.value.name}"
target_type = each.value.target_type
port = each.value.port
protocol = each.value.protocol
protocol_version = each.value.protocol_version
vpc_id = local.vpc_id
stickiness {
type = "source_ip"
enabled = false
}
health_check {
path = each.value.path_health_check
port = each.value.port
healthy_threshold = 3
unhealthy_threshold = 3
interval = 30
}
depends_on = [
aws_lb.main,
]
}
resource "aws_lb_listener" "frontend_http_tcp" {
for_each = var.http_tcp_listeners
load_balancer_arn = aws_lb.main.arn
port = each.value.port
protocol = each.value.protocol
certificate_arn = data.terraform_remote_state.acm.outputs.acm_certificate_arn
alpn_policy = each.value.alpn_policy
dynamic "default_action" {
for_each = aws_lb_target_group.main
content {
type = "forward"
target_group_arn = each.value.arn
}
}
depends_on = [
aws_lb.main,
aws_lb_target_group.main,
]
}

Answer 1

When you use dynamic blocks, your key is not each, but the name of the block. So I think it should be:
target_group_arn = default_action.value.arn
To have only one default_action, try:
default_action {
type = "forward"
target_group_arn = aws_lb_target_group.main[each.key].arn
}