azurerm_virtual_network_gateway resource causes panic when vpn_client_configuration block is specified

[odee30]

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Terraform Version

1.9.8

AzureRM Provider Version

4.11.0

Affected Resource(s)/Data Source(s)

azurerm_virtual_network_gateway

Terraform Configuration Files

terraform {
  required_version = "= 1.9.8"

  required_providers {
    azurerm = {
      source  = "hashicorp/azurerm"
      version = "4.11.0"
    }
  }
}

provider "azurerm" {
  features {}
}

resource "azurerm_resource_group" "this" {
  name     = "rg-example"
  location = "uksouth"
}

resource "azurerm_virtual_network" "this" {
  name                = "vnet-example"
  resource_group_name = azurerm_resource_group.this.name
  location            = azurerm_resource_group.this.location
  address_space       = ["10.0.0.0/16"]
}

resource "azurerm_subnet" "this" {
  name                 = "GatewaySubnet"
  resource_group_name  = azurerm_resource_group.this.name
  virtual_network_name = azurerm_virtual_network.this.name
  address_prefixes     = ["10.0.0.0/27"]
}

resource "azurerm_public_ip" "this" {
  name                = "pip-example"
  resource_group_name = azurerm_resource_group.this.name
  location            = azurerm_resource_group.this.location
  allocation_method   = "Dynamic"
  sku                 = "Basic"
}

resource "azurerm_virtual_network_gateway" "this" {
  name                = "vgw-example"
  resource_group_name = azurerm_resource_group.this.name
  location            = azurerm_resource_group.this.location
  type                = "Vpn"
  vpn_type            = "RouteBased"
  sku                 = "Basic"

  ip_configuration {
    name                          = "ipconfig-example"
    subnet_id                     = azurerm_subnet.this.id
    private_ip_address_allocation = "Dynamic"
    public_ip_address_id          = azurerm_public_ip.this.id
  }

  vpn_client_configuration {
    address_space = ["10.0.1.0/24"]
  }
}

Debug Output/Panic Output

Error: Plugin did not respond
│ 
│   with azurerm_virtual_network_gateway.this,
│   on main.tf line 43, in resource "azurerm_virtual_network_gateway" "this":
│   43: resource "azurerm_virtual_network_gateway" "this" {
│ 
│ The plugin encountered an error, and failed to respond to the plugin.(*GRPCProvider).ApplyResourceChange call. The plugin logs may contain more details.
╵

Stack trace from the terraform-provider-azurerm_v4.11.0_x5 plugin:

panic: interface conversion: interface {} is *schema.Set, not []interface {}

goroutine 417 [running]:
github.com/hashicorp/terraform-provider-azurerm/internal/services/network.expandVirtualNetworkGatewayVpnClientConfig(0xe1cc720?, {{0xc000084014, 0x24}, {0xc002ffded0, 0xa}, {0xc002ffdeb4, 0xb}})
        github.com/hashicorp/terraform-provider-azurerm/internal/services/network/virtual_network_gateway_resource.go:1096 +0x1ae5
github.com/hashicorp/terraform-provider-azurerm/internal/services/network.getVirtualNetworkGatewayProperties({{0xc000084014, 0x24}, {0xc002ffded0, 0xa}, {0xc002ffdeb4, 0xb}}, 0xc00366a580)
        github.com/hashicorp/terraform-provider-azurerm/internal/services/network/virtual_network_gateway_resource.go:935 +0x7bb
github.com/hashicorp/terraform-provider-azurerm/internal/services/network.resourceVirtualNetworkGatewayCreate(0xc00366a580, {0x71c0de0, 0xc001f18488})
        github.com/hashicorp/terraform-provider-azurerm/internal/services/network/virtual_network_gateway_resource.go:675 +0x3fc
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).create(0x8a7d228?, {0x8a7d228?, 0xc00366cc30?}, 0xd?, {0x71c0de0?, 0xc001f18488?})
        github.com/hashicorp/terraform-plugin-sdk/v2@v2.35.0/helper/schema/resource.go:794 +0x15f
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*Resource).Apply(0xc00183b7a0, {0x8a7d228, 0xc00366cc30}, 0xc003676680, 0xc00366a400, {0x71c0de0, 0xc001f18488})
        github.com/hashicorp/terraform-plugin-sdk/v2@v2.35.0/helper/schema/resource.go:937 +0xa89
github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema.(*GRPCProviderServer).ApplyResourceChange(0xc00059ab88, {0x8a7d228?, 0xc00366cb70?}, 0xc003628af0)
        github.com/hashicorp/terraform-plugin-sdk/v2@v2.35.0/helper/schema/grpc_provider.go:1155 +0xd5c
github.com/hashicorp/terraform-plugin-mux/tf5muxserver.(*muxServer).ApplyResourceChange(0xc001bd2380, {0x8a7d228?, 0xc00366c8a0?}, 0xc003628af0)
        github.com/hashicorp/terraform-plugin-mux@v0.17.0/tf5muxserver/mux_server_ApplyResourceChange.go:36 +0x193
github.com/hashicorp/terraform-plugin-go/tfprotov5/tf5server.(*server).ApplyResourceChange(0xc001942c80, {0x8a7d228?, 0xc00366c0c0?}, 0xc0006e6a10)
        github.com/hashicorp/terraform-plugin-go@v0.25.0/tfprotov5/tf5server/server.go:865 +0x3d0
github.com/hashicorp/terraform-plugin-go/tfprotov5/internal/tfplugin5._Provider_ApplyResourceChange_Handler({0x7f68080, 0xc001942c80}, {0x8a7d228, 0xc00366c0c0}, 0xc00366a100, 0x0)
        github.com/hashicorp/terraform-plugin-go@v0.25.0/tfprotov5/internal/tfplugin5/tfplugin5_grpc.pb.go:611 +0x1a6
google.golang.org/grpc.(*Server).processUnaryRPC(0xc0001b4e00, {0x8a7d228, 0xc00366c030}, {0x8aab440, 0xc001df6820}, 0xc0036679e0, 0xc00146b080, 0xe15a2b8, 0x0)
        google.golang.org/grpc@v1.67.1/server.go:1394 +0xe49
google.golang.org/grpc.(*Server).handleStream(0xc0001b4e00, {0x8aab440, 0xc001df6820}, 0xc0036679e0)
        google.golang.org/grpc@v1.67.1/server.go:1805 +0xe8b
google.golang.org/grpc.(*Server).serveStreams.func2.1()
        google.golang.org/grpc@v1.67.1/server.go:1029 +0x8b
created by google.golang.org/grpc.(*Server).serveStreams.func2 in goroutine 52
        google.golang.org/grpc@v1.67.1/server.go:1040 +0x125

Error: The terraform-provider-azurerm_v4.11.0_x5 plugin crashed!

Expected Behaviour

Resource should deploy successfully.

Actual Behaviour

Fails with above error

Steps to Reproduce

No response

Important Factoids

Successfully deploys if the vpn_client_configuration block is removed

References

No response

[stephybun]

Duplicate of #28097. Closed by #28099.

[github-actions]

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