Azurerm_linux_web_app cannot create docker web app - The parameter LinuxFxVersion has an invalid value

Terraform Providers Azure
1

Hi,

I would like to create an Azure Web App Service, which uses a docker image from an Azure Container Registry.

I am using the following terraform script:

terraform {
  required_providers {
    azurerm = {
      source = "hashicorp/azurerm"
      version = "3.9.0"
    }
  }
  backend "azurerm" {
    resource_group_name  = "myproject-westeurope-rg"
    storage_account_name = "myprojectsharedstorage"
    container_name       = "terraform"
    key                  = "admin/terraform.tfstate"
  }

}

provider "azurerm" {
  features {}
}

locals {
  rg-myproject = azurerm_resource_group.myproject.name
  location = "westeurope"
}

resource "random_id" "uniqueid" {
  byte_length = 4
}

resource "azurerm_resource_group" "myproject" {
  name     = "myproject-westeurope-rg"
  location = local.location
}

resource "azurerm_container_registry" "myproject-acr" {
  admin_enabled       = true
  location            = local.location
  name                = "myprojectacr${random_id.uniqueid.hex}"
  resource_group_name = local.rg-myproject
  sku                 = "Basic"
}


resource "azurerm_service_plan" "azappplan" {
  name                = "azappplan"
  location            = local.location
  resource_group_name = local.rg-myproject
  os_type             = "Linux"
  sku_name            = "P1v3"
}

resource "azurerm_linux_web_app" "azapp-docker" {
  name                    = "azapp-docker-${random_id.uniqueid.hex}"
  location                = local.location
  resource_group_name     = local.rg-myproject
  service_plan_id         = azurerm_service_plan.azappplan.id
  https_only              = true
  client_affinity_enabled = true

  identity {
    type = "SystemAssigned"
  }

  site_config {
    always_on      = "true"
    #linux_fx_version = "DOTNETCORE|6.0"

    application_stack {
      docker_image     = "DOCKER|${azurerm_container_registry.myproject-acr.login_server}/myimage:latest"
      docker_image_tag = "latest"
      dotnet_version   = "6.0"
    }
  }
}

resource "azurerm_linux_web_app_slot" "azapp-docker-staging" {
  name                    = "staging"
  app_service_id          = azurerm_linux_web_app.azapp-docker.id
  https_only              = true
  client_affinity_enabled = true
  site_config {

  }
}

If I execute that script I get the following error:

Error: creating Linux Web App: (Site Name “azapp-docker-12345678” / Resource Group “myproject-westeurope-rg”): web.AppsClient#CreateOrUpdate: Failure sending request: StatusCode=400 – Original Error: Code=“BadRequest” Message=“The parameter LinuxFxVersion has an invalid value.” Details=[{“Message”:“The parameter LinuxFxVersion has an invalid value.”},{“Code”:“BadRequest”},{“ErrorEntity”:{“Code”:“BadRequest”,“ExtendedCode”:“01007”,“Message”:“The parameter LinuxFxVersion has an invalid value.”,“MessageTemplate”:“The parameter {0} has an invalid value.”,“Parameters”:[“LinuxFxVersion”]}}]

If I try to set linux_fx_version I get the following error:

Can’t configure a value for “site_config.0.linux_fx_version”: its value will be decided automatically based on the result of applying this configuration.

Could someone please tell me, what I am doing wrong? I can’t find any missing configurations in the documentation.

1 Like
2

Hi.

I had almost exactly the same problem as you, and eventually found a solution.

I think the main problem is in the the “docker_image” variable.
I have modified your code, so that it resembles my solution:

site_config {
    always_on      = "true"

    application_stack {
      docker_image     = "${azurerm_container_registry.myproject-acr.login_server}/myimage"
      docker_image_tag = "latest"
      dotnet_version   = "6.0"
    }
  }

The next step for me was to add the following appsettings.

app_settings = {
        "DOCKER_REGISTRY_SERVER_PASSWORD" = azurerm_container_registry.myproject-acr.admin_password
        "DOCKER_REGISTRY_SERVER_URL" = azurerm_container_registry.myproject-acr.login_server
        "DOCKER_REGISTRY_SERVER_USERNAME" = azurerm_container_registry.myproject-acr.admin_username
    }

After this, everything worked as expected.

Hope this helps

2 Likes
3

Apologies for the late response.

This solutions works. Thank you very much!

4

Is there a way to do this without the DOCKER_REGISTRY_SERVER_USERNAME / DOCKER_REGISTRY_SERVER_PASSWORD.
I want to not use credentials to authenticate to the registry but instead used managed identities.

1 Like
5

Good question, I cannot find any info about that in the documentation. For Azure Container Registry I expect to use Managed Identity (and as a result no need to store user password/login in terraforms var files).