azureconditional-statementsdevopsazure-virtual-networkvnet

Unable to create new VNet in a specified resource group after checking its existence


Here I'm using data blocks for retrieve the information of Vnet if it already exist. If VNet is not existing than create a new one with the same name. I have defined everything properly.

data "azurerm_virtual_network" "existing_vnet" {
  name                = var.vnet_name
  resource_group_name = data.azurerm_resource_group.existing_rg.name
}

locals {
  vnet_exists = length(data.azurerm_virtual_network.existing_vnet) > 0
}

resource "azurerm_virtual_network" "my_vnet" {
  count = local.vnet_exists ? 0 : 1

  name                = var.vnet_name
  address_space       = var.address_space
  location            = data.azurerm_resource_group.existing_rg.location
  resource_group_name = data.azurerm_resource_group.existing_rg.name
}

But after running terraform apply it shows me an error of:

Error: Error: Virtual Network: (Name "axis_VN" / Resource Group "training") was not found
│ 
│   with data.azurerm_virtual_network.existing_vnet,
│   on main.tf line 24, in data "azurerm_virtual_network" "existing_vnet":
│   24: data "azurerm_virtual_network" "existing_vnet" {

can any one help me in this?

I was expecting that VNet would only create if it doesn't exit in the resource group


Solution

  • I tried to check with following code , to check for existing resources

    data "azurerm_virtual_network" "existing_vnet" {
      name                = "myVnet"
      resource_group_name = data.azurerm_resource_group.example.name
    }
    
    locals {
      vnet_exists = length(data.azurerm_virtual_network.existing_vnet) > 0
    }
    
    output "vnetcout" {
      value = local.vnet_exists
    }
    

    It gives error as "resource not found " if it does not exist already .

    enter image description here

    For this External Data source can be used : external_external | Data Sources | hashicorp/external | Terraform Registry as Terraform does not check for preexisting resources.

    Here almost any programming language can be used. One such example i tried to create VM if it does not exist.

    data "external" "vm_exists" {
          program = ["Powershell.exe", "C:\\Users\\xx\\checkexistence.ps1"]
        }
    
     output "vmexistsornot" {
          value = "${data.external.vm_exists.result.value}"
        }
    

    Powershell code: Checkexistence.ps1

    $rgName = "myrg"
        $vmName = "excpectedm"
        $vmExists = Get-AzVM -Name $vmName -ResourceGroupName $rgName -ErrorAction SilentlyContinue  
       # $vmexistsmsg="VM exists"
       # $vmnotexistsmsg="VM does not exist"
        if (!$vmExists) {
        Write-Output '{"value" :  "true" }'   
        } else {
        Write-Output '{"value" :  "false" }'
          
        }
    

    Initially checked only for non existence:It has to return true.

    enter image description here

    Then if the Vm doesnot exist , it will be created.

    resource "azurerm_network_interface" "example" {
      name                = "kaexample-nic"
     location            = data.azurerm_resource_group.example.location
      resource_group_name = data.azurerm_resource_group.example.name
      ip_configuration {
        name                          = "example-ip-config"
        subnet_id                     = azurerm_subnet.example.id
        private_ip_address_allocation = "Dynamic"
      }
    }
    
    resource "azurerm_virtual_network" "example" {
      name                = "kaexample-virtual-network"
      address_space       = ["10.0.0.0/16"]
      location            = data.azurerm_resource_group.example.location
      resource_group_name = data.azurerm_resource_group.example.name
    }
    
    resource "azurerm_subnet" "example" {
      name                 = "kkexample-subnet"
      address_prefixes     = ["10.0.0.0/24"]
      virtual_network_name = azurerm_virtual_network.example.name
      resource_group_name  = data.azurerm_resource_group.example.name
    }
    
    
    resource "azurerm_virtual_machine" "new_vm" {
      count = data.external.vm_exists.result.value == "true" ? 1 : 0
    
      name                = var.vm_name
      resource_group_name = var.resource_group_name
      location            = "eastus"
       vm_size               = "Standard_D4as_v5"
       network_interface_ids =  [azurerm_network_interface.example.id]
    
      
    
      storage_os_disk {
        name               = "my_os_storage_disk"
        caching            = "ReadWrite"
        create_option      = "FromImage"
        managed_disk_type  = "Standard_LRS"
      }
    
      os_profile {
        computer_name  = "myvm"
        admin_username = "azureuser"
        admin_password = "MyComplexPassword"
      }
    
      os_profile_windows_config {
      }
    
      # other configuration settings...
    
    
    }
    
    resource "azurerm_virtual_machine" "new_vm" {
      count = data.external.vm_exists.result.value == true ? 0 : 1
      name                = var.vm_name
      resource_group_name = var.resource_group_name
      location            = "eastus"
    }
    

    enter image description here