Check if the resource exists before using data

Question

I want to check if the resource exists before I run below code. I also want to use output of this code further in the code.

data "azurerm_api_management" "res-data" {
  name                = "res_name"
  resource_group_name = "rg_name"
}

resource "azurerm_api_management" "apim" {
  name                = "res_name"
  location            = var.location
  resource_group_name = "rg_name"
  publisher_email     = data.azurerm_api_management.res-data.publisher_email
  }

Answer 1

Check if the resource exists before using data module in terraform

There is no in-build feature in terraform to check the existence of resource before using data module in terraform.

In general, data module is used for the resource which is preexisted if the resource doesn't exists this will through an error. Since the requirement is to check the existence of resource in portal before running the data module, we need external script support using cli to achieve this requirement.

Configuration:

variable "apim_name" {
  type        = string
  description = "The name of the API Management resource"
  default     = ""
}

resource "null_resource" "check_apim_existence" {
  provisioner "local-exec" {
    command = <<EOT
      apim_exists=$(az apim show --name ${var.apim_name} --resource-group vinay-rg --query "name" -o tsv)
      if [ -n "$apim_exists" ]; then
        echo "APIM exists: $apim_exists"
      else
        echo "APIM does not exist"
        exit 1
      fi
    EOT
    interpreter = ["bash", "-c"]
  }

  triggers = {
    always_run = "${timestamp()}"
  }
}

data "azurerm_api_management" "res_data" {
  depends_on          = [null_resource.check_apim_existence]  
  name                = var.apim_name
  resource_group_name = "vinay-rg"
}

output "apim_name" {
  value = data.azurerm_api_management.res_data.name
  description = "The name of the API Management resource"
}

Deployment:

with this script we can make sure the existence of resource name mentioned under our RG.

If the resource doesn't exist it will through the error at null resource level mentioning the same as we use depends on in data module.

Refer:

azurerm_api_management | Data Sources | hashicorp/azurerm | Terraform | Terraform Registry

https://learn.microsoft.com/en-us/cli/azure/apim?view=azure-cli-latest#az-apim-show