azurerm_linux_web_app_slot ignores worker_count parameter in site_config block

[dkanbier]

Is there an existing issue for this?

• I have searched the existing issues

Community Note

• Please vote on this issue by adding a 👍 reaction to the original issue to help the community and maintainers prioritize this request
• Please do not leave "+1" or "me too" comments, they generate extra noise for issue followers and do not help prioritize the request
• If you are interested in working on this issue or have submitted a pull request, please leave a comment and review the contribution guide to help.

Terraform Version

1.7.1

AzureRM Provider Version

3.89.0

Affected Resource(s)/Data Source(s)

azurerm_linux_web_app_slot

Terraform Configuration Files

resource "random_integer" "ri" {
  min = 10000
  max = 99999
}

# Create the resource group
resource "azurerm_resource_group" "rg" {
  name     = "myResourceGroup-${random_integer.ri.result}"
  location = "westeurope"
}

# Create the Linux App Service Plan
resource "azurerm_service_plan" "appserviceplan" {
  name                     = "webapp-asp-${random_integer.ri.result}"
  location                 = azurerm_resource_group.rg.location
  resource_group_name      = azurerm_resource_group.rg.name
  os_type                  = "Linux"
  sku_name                 = "P1v3"
  per_site_scaling_enabled = true
  worker_count             = 2
}

# Create the web app, pass in the App Service Plan ID
resource "azurerm_linux_web_app" "webapp" {
  name                = "webapp-${random_integer.ri.result}"
  location            = azurerm_resource_group.rg.location
  resource_group_name = azurerm_resource_group.rg.name
  service_plan_id     = azurerm_service_plan.appserviceplan.id
  https_only          = true
  site_config {
    minimum_tls_version = "1.2"
    worker_count        = 2
  }
}

resource "azurerm_linux_web_app_slot" "webapp_slot" {
  name           = "webapp-staging-${random_integer.ri.result}"
  app_service_id = azurerm_linux_web_app.webapp.id
  site_config {
    minimum_tls_version = "1.2"
    worker_count        = 2
  }
}

Debug Output/Panic Output

PUT request to Azure for the slot:

PUT /subscriptions/SUBSCRIPTION/resourceGroups/myResourceGroup-42718/providers/Microsoft.Web/sites/webapp-42718/slots/webapp-staging-42718?api-version=2022-09-01 HTTP/1.1
Host: management.azure.com
User-Agent: Go/go1.21.3 (arm64-linux) go-autorest/v14.2.1 tombuildsstuff/kermit/v0.20230703.1101016 web/2022-09-01 HashiCorp Terraform/1.7.1 (+https://www.terraform.io) Terraform Plugin SDK/2.10.1 terraform-provider-azurerm/3.89.0 pid-222c6c49-1b0a-5959-a213-6608f9eb8820
Content-Length: 876
Content-Type: application/json; charset=utf-8
X-Ms-Correlation-Request-Id: CORRELATION_ID
Accept-Encoding: gzip

{"identity":{"type":"None"},"location":"West Europe","properties":{"clientAffinityEnabled":false,"clientCertEnabled":false,"clientCertMode":"Required","enabled":true,"httpsOnly":false,"publicNetworkAccess":"Enabled","serverFarmId":"/subscriptions/SUBSCRIPTION/resourceGroups/myResourceGroup-42718/providers/Microsoft.Web/serverFarms/webapp-asp-42718","siteConfig":{"acrUseManagedIdentityCreds":false,"alwaysOn":true,"autoHealEnabled":false,"ftpsState":"Disabled","http20Enabled":false,"loadBalancing":"LeastRequests","localMySqlEnabled":false,"managedPipelineMode":"Integrated","minTlsVersion":"1.2","publicNetworkAccess":"Enabled","remoteDebuggingEnabled":false,"scmIpSecurityRestrictionsUseMain":false,"scmMinTlsVersion":"1.2","use32BitWorkerProcess":true,"vnetRouteAllEnabled":false,"webSocketsEnabled":false},"vnetRouteAllEnabled":false},"tags":{}}: timestamp="2024-01-29T11:26:13.124+0100"

Payload:

{
  "identity": {
    "type": "None"
  },
  "location": "West Europe",
  "properties": {
    "clientAffinityEnabled": false,
    "clientCertEnabled": false,
    "clientCertMode": "Required",
    "enabled": true,
    "httpsOnly": false,
    "publicNetworkAccess": "Enabled",
    "serverFarmId": "/subscriptions/SUBSCRIPTION/resourceGroups/myResourceGroup-42718/providers/Microsoft.Web/serverFarms/webapp-asp-42718",
    "siteConfig": {
      "acrUseManagedIdentityCreds": false,
      "alwaysOn": true,
      "autoHealEnabled": false,
      "ftpsState": "Disabled",
      "http20Enabled": false,
      "loadBalancing": "LeastRequests",
      "localMySqlEnabled": false,
      "managedPipelineMode": "Integrated",
      "minTlsVersion": "1.2",
      "publicNetworkAccess": "Enabled",
      "remoteDebuggingEnabled": false,
      "scmIpSecurityRestrictionsUseMain": false,
      "scmMinTlsVersion": "1.2",
      "use32BitWorkerProcess": true,
      "vnetRouteAllEnabled": false,
      "webSocketsEnabled": false
    },
    "vnetRouteAllEnabled": false
  },
  "tags": {}
}

Expected Behaviour

The resulting azurerm_linux_web_app_slot in Azure should have a worker_count of 2.

Actual Behaviour

The resulting azurerm_linux_web_app_slot in Azure has a default worker_count of 1:

$ az webapp deployment slot list --resource-group myResourceGroup-42718 --name webapp-42718  | jq '.[] | select(.name=="webapp-staging-42718") | .siteConfig.numberOfWorkers'

1

When running terraform plan directly after the apply it will always show differences:

Terraform used the selected providers to generate the following execution plan. Resource actions are indicated with the following symbols:
  ~ update in-place

Terraform will perform the following actions:

  # azurerm_linux_web_app_slot.webapp_slot will be updated in-place
  ~ resource "azurerm_linux_web_app_slot" "webapp_slot" {
        id                                             = "/subscriptions/SUBSCRIPTION/resourceGroups/myResourceGroup-42718/providers/Microsoft.Web/sites/webapp-42718/slots/webapp-staging-42718"
        name                                           = "webapp-staging-42718"
        tags                                           = {}
        # (20 unchanged attributes hidden)

      ~ site_config {
          ~ worker_count                            = 1 -> 2
            # (20 unchanged attributes hidden)

            # (1 unchanged block hidden)
        }
    }

Plan: 0 to add, 1 to change, 0 to destroy.

Steps to Reproduce

1. terraform apply
2. terraform plan
3. The plan will output changes in the worker_count

Important Factoids

Notice the NumberOfWorkers parameter is missing from the siteConfig block in the debug output. I think the missing parameter is the cause of this issue. I've created PR #24515 which solves the issue in my testing.

References

Documentation:
https://registry.terraform.io/providers/hashicorp/azurerm/latest/docs/resources/linux_web_app_slot#worker_count

Related PR:
#24515

[github-actions]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.
If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.