Argument or block definition required - terraform

Question

I am using kubernetes_network_policy resource. I have around ten network poilices and each of them is different. I want the from cidr block to be executed only when I pass a value to ingress_to_cidr. When I am trying execute terragrunt apply it errors out saying failed to expand IPBlock: null or empty input but terragrunt plan works fine. So I am trying to use if statement around the from cidr block, to see if I surpass the IPblock issue when I don't pass any value to ingress_to_cidr
│ Error: Argument or block definition required
│
│ on main.tf line 37, in resource "kubernetes_network_policy" "example-policy":
│ 37: length(var.ingress_to_cidr) != 0 ? 0 : from {
│
│ An argument or block definition is required here. To set an argument, use
│ the equals sign "=" to introduce the argument value.
╵
ERRO[0004] 1 error occurred:
* exit status 1
My resource
resource "kubernetes_network_policy" "example-policy" {
for_each = var.inputs
metadata {
name = each.value.name
namespace = each.value.namespace
}
spec {
pod_selector {
match_labels = {
app = each.value.selector
}
}
policy_types = each.value.policy
dynamic "ingress" {
for_each = each.value.egress_number == null ? [] :range(length(each.value.ingress_number))
content {
ports {
port = each.value.ingress_number[ingress.value]
protocol = each.value.ingress_protocol[ingress.value]
}
length(var.ingress_to_cidr) == null ? [] : from {
ip_block {
cidr = each.value.ingress_to_cidr
}
}
}
}
dynamic "egress" {
for_each = each.value.egress_number == null ? [] : range(length(each.value.egress_number))
content {
ports {
port = each.value.egress_number[egress.value]
protocol = each.value.egress_protocol[egress.value]
}
length(var.ingress_to_cidr) == null ? [] : to {
ip_block {
cidr = each.value.egress_to_cidr
}
}
}
}
}
}

Answer 1

You can nest dynamic blocks. So I think in your case it should be:
resource "kubernetes_network_policy" "example-policy" {
for_each = var.inputs
metadata {
name = each.value.name
namespace = each.value.namespace
}
spec {
pod_selector {
match_labels = {
app = each.value.selector
}
}
policy_types = each.value.policy
dynamic "ingress" {
for_each = each.value.egress_number == null ? [] : range(length(each.value.ingress_number))
content {
ports {
port = each.value.ingress_number[ingress.value]
protocol = each.value.ingress_protocol[ingress.value]
}
dynamic "from" {
for_each = each.value.ingress_to_cidr == null ? [] : [each.value.ingress_to_cidr]
content {
ip_block {
cidr = from.value
}
}
}
}
}
dynamic "egress" {
for_each = each.value.egress_number == null ? [] : range(length(each.value.egress_number))
content {
ports {
port = each.value.egress_number[egress.value]
protocol = each.value.egress_protocol[egress.value]
}
dynamic "from" {
for_each = each.value.egress_to_cidr == null ? [] : [each.value.egress_to_cidr]
content {
ip_block {
cidr = from.value
}
}
}
}
}
}
}