Support for azurerm_virtual_hub_route_table route as a distinct resource.

[TomKimber]

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Description

Support for azurerm_virtual_hub_route_table routes as a distinct resource. This would be useful as in the current implementation to routes for a azurerm_virtual_hub_route_table are created in the route block, a required parameter in that block is "next_hop", "next_hop" requires a azurerm_virtual_hub_connection ID.

If I'm defining a azurerm_virtual_hub_connection in the same Terraform and I want to either associate the route table with the connection using the "associated_route_table_id" in the routing block or associate a list of route table resources with the connection via the route_table_ids in the propagated_route_table block this causes a cyclical dependency due to the route requiring a connection to create and the connection requiring a route table to create. This would be solved if the azurerm_virtual_hub_route_table route could be created as a distinct resource in line with the way regular Route Table/Routes can be created.

New or Affected Resource(s)

• azurerm_virtual_hub_route_table
• azurerm_virtual_hub_connection

Potential Terraform Configuration

resource "azurerm_virtualhub_route" "example" {
  name              = "acceptanceTestRoute1"
  destinations_type = "CIDR"
  destinations      = ["10.0.0.0/16"] 
  next_hop_type     = "ResourceId"
  next_hop          = azurerm_virtual_hub_connection.example.id
  route_table = azurerm_virtual_hub_route_table.example.id
}

References

• https://docs.microsoft.com/en-us/azure/virtual-wan/how-to-virtual-hub-routing

[josh-barker]

Hi all,

I've been looking at how we can solve this.
From what I can find, there isn't an API for a single route.
If we were to implement a resource as described above, that would mean that for each route there would be multiple API calls to GET, PUT/POST to the Route Table API. Each Route resource would have to be run sequentially so that the Route Table ends up with all of the routes in the end.

Let me know if I have overlooked something.

I have 2 additional options.

1. Option 1: A routing configuration resource - new resource: azurerm_virtual_hub_connection_routing
   How does this help?
   It allows the connection to be created, then the route table can create routes that refer back to the connection.
   Finally, the azurerm_virtual_hub_connection_routing resource can associate the route table to the connection.

This option also allows the propagated route tables and static routes to be managed in this new resource.

The downside to this is that you can either configure a connection inside the azurerm_virtual_hub_connection resource or the azurerm_virtual_hub_connection_routing resource, but not both.

resource "azurerm_virtual_hub" "example" {
  name                = "example-vhub"
  resource_group_name = azurerm_resource_group.example.name
  location            = azurerm_resource_group.example.location
  virtual_wan_id      = azurerm_virtual_wan.example.id
  address_prefix      = "10.0.2.0/24"
}

resource "azurerm_virtual_hub_connection" "example" {
  name                      = "example-vhubconn"
  virtual_hub_id            = azurerm_virtual_hub.example.id
  remote_virtual_network_id = azurerm_virtual_network.example.id
}

resource "azurerm_virtual_hub_route_table" "example" {
  name           = "example-vhubroutetable"
  virtual_hub_id = azurerm_virtual_hub.example.id
  labels         = ["label1"]

  route {
    name              = "example-route"
    destinations_type = "CIDR"
    destinations      = ["10.0.0.0/16"]
    next_hop_type     = "ResourceId"
    next_hop          = azurerm_virtual_hub_connection.example.id
  }
}

resource "azurerm_virtual_hub_connection_routing" "example" {
  virtual_hub_connection_id = azurerm_virtual_hub_connection.example.id

  associated_route_table_id = azurerm_virtual_hub_route_table.example.id

  propagated_route_table {
      labels = ["some", "labels"]
      route_table_ids = [
        azurerm_virtual_hub_route_table.example1.id, 
        azurerm_virtual_hub_route_table.example2.id
      ]
  }

  static_vnet_route {
    name                = "testvnetroute"
    address_prefixes    = ["10.0.3.0/24", "10.0.4.0/24"]
    next_hop_ip_address = "10.0.3.5"
  }

  static_vnet_route {
    name                = "testvnetroute2"
    address_prefixes    = ["10.0.5.0/24"]
    next_hop_ip_address = "10.0.5.5"
  }
}

2. Association resources - New resources: azurerm_virtual_hub_connection_route_table_association, azurerm_virtual_hub_connection_propagation_route_table_association
   How does this help?
   It allows the connection to be created, then the route table can create routes that refer back to the connection.
   Finally, the azurerm_virtual_hub_connection_route_table_association resource can associate the route table to the connection.

The downside to this option is that multiple resources would need to be created for each of the elements in the routing block.

resource "azurerm_virtual_hub" "example" {
  name                = "example-vhub"
  resource_group_name = azurerm_resource_group.example.name
  location            = azurerm_resource_group.example.location
  virtual_wan_id      = azurerm_virtual_wan.example.id
  address_prefix      = "10.0.2.0/24"
}

resource "azurerm_virtual_hub_connection" "example" {
  name                      = "example-vhubconn"
  virtual_hub_id            = azurerm_virtual_hub.example.id
  remote_virtual_network_id = azurerm_virtual_network.example.id
}

resource "azurerm_virtual_hub_route_table" "example" {
  name           = "example-vhubroutetable"
  virtual_hub_id = azurerm_virtual_hub.example.id
  labels         = ["label1"]

  route {
    name              = "example-route"
    destinations_type = "CIDR"
    destinations      = ["10.0.0.0/16"]
    next_hop_type     = "ResourceId"
    next_hop          = azurerm_virtual_hub_connection.example.id
  }
}

resource "azurerm_virtual_hub_connection_route_table_association" "example" {
  virtual_hub_connection_id = azurerm_virtual_hub.example.id
  route_table_id            = azurerm_virtual_hub_route_table.example.id
}

I think option 1 is the best way forward, as we only need to make 1 more resource.

I have been able to build a rough implementation of option 2 and will begin implementing option 1.

I'll create 2 x draft PRs and link to this issues for further discussion.

[NikolaiKleppe]

Hi, I see that #11644 was closed as duplicate to this issue. @tombuildsstuff

Do you know if the fix you're working on @josh-barker will help with this, as suggested in the issue above? Just to make sure we're aligned here as that one is a pretty important issue as well.

[github-actions]

This functionality has been released in v2.82.0 of the Terraform Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[josh-barker]

Hey @NikolaiKleppe, yep this new route resource can be used to create a route on a default route table.
For example:

resource "azurerm_virtual_hub_route_table_route" "example" {
  route_table_id = "${azurerm_virtual_hub.example.id}/hubRouteTables/defaultRouteTable"

  name              = "example-route"
  destinations_type = "CIDR"
  destinations      = ["10.0.0.0/16"]
  next_hop_type     = "ResourceId"
  next_hop          = azurerm_virtual_hub_connection.example.id
}

As that's a bit clunky, I'm going to create a new PR to add default_route_table_id to the azurerm_virtual_hub resource.

Example configuration:

resource "azurerm_virtual_hub_route_table_route" "example" {
  route_table_id = azurerm_virtual_hub.example.default_route_table_id

  name              = "example-route"
  destinations_type = "CIDR"
  destinations      = ["10.0.0.0/16"]
  next_hop_type     = "ResourceId"
  next_hop          = azurerm_virtual_hub_connection.example.id
}

I'll mention this issue and #11644 in the new PR when I've created it.

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.