Setting Azure App Service server stack on a Bicep template

Question

I'm trying to deploy a .NET Core 3.1 Azure App Service on Linux using a Bicep template from Azure CLI. The app service and corresponding app service plan are deployed correctly but the app service stack settings are empty on the Azure portal and I have to set these manually. I tried setting the metadata property on the 'Microsoft.Web/sites' resource and also on the 'Microsoft.Web/sites/config' resource, but the result was the same.

This is my app service plan:

resource appServicePlan 'Microsoft.Web/serverfarms@2021-02-01' = {
  name: 'MyAppService'
  location: resourceGroup().location
  properties: {
    reserved: true
  }
  sku: {
    name: 'P1v2'
  }
  kind: 'linux'
}

Here is my first attempt to set the stack using 'Microsoft.Web/sites' as suggested here:

https://github.com/Azure/bicep/issues/3314

resource appService 'Microsoft.Web/sites@2021-02-01' = {
  name: 'MyApp'
  location: resourceGroup().location
  identity: {
    type: 'SystemAssigned'
  }
  kind: 'app'
  properties: {
    enabled: true
    serverFarmId: appServicePlan.id
    siteConfig: {
      linuxFxVersion: 'dotnet|3.1'
      appCommandLine: 'dotnet MyApp.dll'
      metadata: [
        {
          name: 'CURRENT_STACK'
          value: 'dotnetcore'
        }
      ]
    }
  }
}

Here is my second attempt to set the stack using 'Microsoft.Web/sites/config' as suggested here:

Bicep - How to config Runtime Stack to Azure App Service (Bicep version 0.4)

resource appService 'Microsoft.Web/sites@2021-02-01' = {
  name: 'MyApp'
  location: resourceGroup().location
  identity: {
    type: 'SystemAssigned'
  }
  kind: 'app'
  properties: {
    enabled: true
    serverFarmId: appServicePlan.id
    siteConfig: {
      linuxFxVersion: 'dotnet|3.1'
      appCommandLine: 'dotnet MyApp.dll'
    }
  }
  resource webConfig 'config' = {
    name: 'web'
    properties: {
      metadata: [
        {
          name: 'CURRENT_STACK'
          value: 'dotnetcore'
        }
      ]
    }
  }
}

The result is the same. The deployment is completed with the following warning:

Warning BCP037: The property "metadata" is not allowed on objects of type "SiteConfig". Permissible properties include "acrUseManagedIdentityCreds", "acrUserManagedIdentityID", "alwaysOn", "apiDefinition", "apiManagementConfig", "autoHealEnabled", "autoHealRules", "autoSwapSlotName", "azureStorageAccounts", "connectionStrings", "cors", "defaultDocuments", "detailedErrorLoggingEnabled", "documentRoot", "experiments", "ftpsState", "functionAppScaleLimit", "functionsRuntimeScaleMonitoringEnabled", "handlerMappings", "healthCheckPath", "http20Enabled", "httpLoggingEnabled", "ipSecurityRestrictions", "javaContainer", "javaContainerVersion", "javaVersion", "keyVaultReferenceIdentity", "limits", "loadBalancing", "localMySqlEnabled", "logsDirectorySizeLimit", "managedPipelineMode", "managedServiceIdentityId", "minimumElasticInstanceCount", "minTlsVersion", "netFrameworkVersion", "nodeVersion", "numberOfWorkers", "phpVersion", "powerShellVersion", "preWarmedInstanceCount", "publicNetworkAccess", "publishingUsername", "push", "pythonVersion", "remoteDebuggingEnabled", "remoteDebuggingVersion", "requestTracingEnabled", "requestTracingExpirationTime", "scmIpSecurityRestrictions", "scmIpSecurityRestrictionsUseMain", "scmMinTlsVersion", "scmType", "tracingOptions", "use32BitWorkerProcess", "virtualApplications", "vnetName", "vnetPrivatePortsCount", "vnetRouteAllEnabled", "websiteTimeZone", "webSocketsEnabled", "windowsFxVersion", "xManagedServiceIdentityId". If this is an inaccuracy in the documentation, please report it to the Bicep Team. [https://aka.ms/bicep-type-issues]

The resources are deployed, but the app service stack setting is blank and I have to set it manually to make it work.

I know that in the ARM template this is set on the CURRENT_STACK property of the Microsoft.Web/sites/config metadata (as suggested here https://cloudstep.io/2020/11/18/undocumented-arm-oddities-net-core-app-services/). However, this doesn't seem to be supported (yet) in Bicep. If anyone has found a working solution, please post it here. Thanks.

Answer 1

It's better to use the sites/config to set up the .NET version

resource appServiceConfig 'Microsoft.Web/sites/config@2022-09-01' = {
  name: 'web'
  parent: appService
  properties: {
    netFrameworkVersion: 'v7.0'
    use32BitWorkerProcess: false
    http20Enabled: true
    ftpsState: 'Disabled'
    alwaysOn: true
    metadata: [
      {
        name: 'CURRENT_STACK'
        value: 'dotnet'
      }
    ]
  }
}

Answer 2

The Metadata parameter is not available anymore in the SiteConfig. The stack setting can be mentioned LinuxFxVersion.

So, solution will be Instead of using dotnet|3.1 , You should use DOTNETCORE|3.1.The over all code will be as below:

resource appServicePlan 'Microsoft.Web/serverfarms@2021-02-01' = {
  name: 'MyAppService'
  location: resourceGroup().location
  properties: {
    reserved: true
  }
  sku: {
    name: 'P1v2'
  }
  kind: 'linux'
}
resource appService 'Microsoft.Web/sites@2021-02-01' = {
  name: 'anumantestapp'
  location: resourceGroup().location
  identity: {
    type: 'SystemAssigned'
  }
  kind: 'app'
  properties: {
    enabled: true
    serverFarmId: appServicePlan.id
    siteConfig: {
      linuxFxVersion: 'DOTNETCORE|3.1'
      appCommandLine: 'dotnet MyApp.dll'
    }
  }
}

Ouptut: