How to omit optional block in Terraform resource based on input variable
The goal is to create azurerm_virtual_hub_connection which might or might not have an optional block called static_vnet_route section under routing {} block.
The goal is to create azurerm_virtual_hub_connection which might or might not have an optional block called static_vnet_route section under routing {} block.
File variables.tf
Define a variable to hold the list of static routes. When the list is empty, the dynamic block will use null values, effectively omitting the optional block.
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variable "static_vnet_routes" {
description = "Static routes for virtual network connection"
type = list(any)
default = []
}
File terraform.tfvars
In the tfvars file, the static routes are commented out by default. Uncomment them when you need to add static routes to the virtual hub connection.
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static_vnet_routes = [
#{
# name = "static_route_1"
# address_prefixes = ["10.0.2.0/24"]
# next_hop_ip_address = "10.0.1.2"
#},
#{
# name = "static_route_2"
# address_prefixes = ["10.0.3.0/24"]
# next_hop_ip_address = "10.0.1.4"
#}
]
And finally the azurerm_virtual_hub_connection resource looks like the following. The dynamic block iterates over the static routes list. When the list is empty, it falls back to a single element with all null values, which Terraform treats as omitting the block entirely.
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resource "azurerm_virtual_hub_connection" "vhub_connection" {
name = var.vhub_connection_name
virtual_hub_id = var.virtual_hub_id
remote_virtual_network_id = azurerm_virtual_network.vnet.id
routing {
# static_vnet_route {}
dynamic "static_vnet_route" {
for_each = length(var.static_vnet_routes) > 0 ? var.static_vnet_routes : tolist(
[
{
name = null
address_prefixes = null
next_hop_ip_address = null
}
]
)
iterator = static_route
content {
name = static_route.value.name
address_prefixes = static_route.value.address_prefixes
next_hop_ip_address = static_route.value.next_hop_ip_address
}
}
}
}