Terraform error : An argument named "count" is not expected here

Question

I am trying to loop the container names using count in the Azure Event Hub in Azure Event Hub namespace. however I am getting to below error while terraform plan.

Below is the Terraform code

resource "azurerm_resource_group" "test-rg" {
  name     = "test-rg"
  location = "eastus"
}

variable "storageaccountname" {
  type = string
  default = "eusstestslogssa01"
}

 variable "containers_list" {
  type = list
  default = [{ name = "eus-a-test-logs-bkp", access_type = "private" },
  { name = "insights-logs-auditevent", access_type = "private" },
  { name = "insights-logs-dataplanerequests", access_type = "private" }  
  ]
 }

 variable "eventhubs" {
  type = list
  default = ["insights-logs-auditevent","insights-logs-dataplanerequests","insights-logs-eventhubvnetconnectionevent"]
}


resource "azurerm_storage_account" "storageaccount" {

  name                     = var.storageaccountname
  resource_group_name      = azurerm_resource_group.test-rg.name
  location                 = azurerm_resource_group.test-rg.location
  account_tier             = "Standard"
  account_replication_type = "LRS"

}

resource "azurerm_storage_container" "container" {

  count                 = length(var.containers_list)
  name                  = var.containers_list[count.index].name
  storage_account_name  = azurerm_storage_account.storageaccount.name
  container_access_type = var.containers_list[count.index].access_type

}


resource "azurerm_eventhub_namespace" "test-ens" {
  depends_on = [
    azurerm_storage_account.storageaccount,
  ]
  name                = "testens"
  location            = azurerm_resource_group.test-rg.location
  resource_group_name = azurerm_resource_group.test-rg.name
  sku                 = "Basic"
  capacity            = 1
  minimum_tls_version = "1.1"

}

resource "azurerm_eventhub" "test-eventhubs" {

  count               = length(var.eventhubs)
  name                = var.eventhubs[count.index]
  namespace_name      = azurerm_eventhub_namespace.test-ens.name
  resource_group_name = azurerm_resource_group.test-rg.name
  partition_count     = 4
  message_retention   = 1
  capture_description {
    enabled  = true
    encoding = "Avro"
    destination {
      count               = length(var.containers_list)
      name                = "EventHubArchive.AzureBlockBlob"
      archive_name_format = "{Namespace}/{EventHub}/{PartitionId}/{Year}-{Month}-{Day}T{Hour}:{Minute}:{Second}"
      blob_container_name = var.containers_list[count.index].name
      storage_account_id  = azurerm_storage_account.storageaccount.id
    }
  }
}

I am new to terraform syntax could someone help on this scenario ? How to write a forloop inside the terraform sub resource ?

Tried dynamic for_each block but hitting with new error. Am I trying with right syntax ?

variable "capture" {

  type = map(object({
    name                   = string
    archive_container_name = string
    blob_container_name    = string
    storage_account_id     = string
  }))

  default = {
    "container1" = {
      name                   = "EventHubArchive.AzureBlockBlob"
      archive_container_name = "{Namespace}/{EventHub}/{PartitionId}/{Year}-{Month}-{Day}T{Hour}:{Minute}:{Second}"
      blob_container_name    = "eus-s-test-logs-bkp"
      storage_account_id     = "azurerm_storage_account.storageaccount.id"
    }
    "container2" = {
      name                   = "EventHubArchive.AzureBlockBlob"
      archive_container_name = "{Namespace}/{EventHub}/{PartitionId}/{Year}-{Month}-{Day}T{Hour}:{Minute}:{Second}"
      blob_container_name    = "insights-logs-auditevent"
      storage_account_id     = "azurerm_storage_account.storageaccount.id"
    }
    "container3" = {
      name                   = "EventHubArchive.AzureBlockBlob"
      archive_container_name = "{Namespace}/{EventHub}/{PartitionId}/{Year}-{Month}-{Day}T{Hour}:{Minute}:{Second}"
      blob_container_name    = "insights-logs-dataplanerequests"
      storage_account_id     = "azurerm_storage_account.storageaccount.id"
    }
  }
}


resource "azurerm_eventhub" "test-eventhubs" {

  count               = length(var.eventhubs)
  name                = var.eventhubs[count.index]
  namespace_name      = azurerm_eventhub_namespace.test-ens.name
  resource_group_name = azurerm_resource_group.test-rg.name
  partition_count     = 4
  message_retention   = 1
  capture_description {
    enabled  = true
    encoding = "Avro"
    dynamic "destination" {
      for_each = var.capture
      content {
      name                = destination.value["name"]
      archive_name_format = destination.value["archive_container_name"]
      blob_container_name = destination.value["blob_container_name"]
      storage_account_id  = destination.value["storage_account_id"]
      }
    }
  }
}

Error :

terraform plan
╷
│ Error: Too many destination blocks
│
│   on eventhub.tf line 121, in resource "azurerm_eventhub" "test-eventhubs":
│  121:       content {
│
│ No more than 1 "destination" blocks are allowed
╵
╷
│ Error: Too many destination blocks
│
│   on eventhub.tf line 121, in resource "azurerm_eventhub" "test-eventhubs":
│  121:       content {
│
│ No more than 1 "destination" blocks are allowed
╵
╷
│ Error: Too many destination blocks
│
│   on eventhub.tf line 121, in resource "azurerm_eventhub" "test-eventhubs":
│  121:       content {
│
│ No more than 1 "destination" blocks are allowed

Answer 1

In my view azurerm_eventhub with dynamic block won't work, usually we use dynamic blocks if and only if the resource you are trying to deploy has configuration within nested blocks. azurerm_eventhub does not. Instead of using dynamic, you must create multiple instances of azurerm_eventhub.

Sample code for dynamic usage

Step1: Instead of variable replace it as local

locals{
containers_list = [
  { name = "eus-a-test-logs-bkp", access_type = "private" },
  { name = "insights-logs-auditevent", access_type = "private" },
  { name = "insights-logs-dataplanerequests", access_type = "private" }  
]
}

Step2: Write Dynamic block as follows

 dynamic "SwarnaDemo" {
   for_each = local.containers_list
    content {
      label = SwarnaDemo.value.name
      size  = SwarnaDemo.value.access_type
      }
  }

Hope it's helpful!