Deploying Azure function with dotnet-isolated doesn't work

[dozer75]

Bicep version
Bicep CLI version 0.6.1 (73193aa4c4)

Describe the bug
Deploying a Azure function with isolated .NET using Bicep creates an App Service for the Azure function, but the App Service is in an invalid state and displays the error WorkerConfig for runtime: dotnet-isolated not found.

I have tried a lot of different ways to create this according to various examples found on the internet, but all variations I have tried generates the error no matter what.

To Reproduce

This is the current test I have in script, it's basically the template created in Bicep extension in Code, but with the addition of the
linux in kind and DOTNET-ISOLATED|5.0 in linuxFxVersion as mentioned here.

Prerequisites:

• variable name
• resource storageAccount
• resource appInsightsComponents

var storageConnectionString = 'DefaultEndpointsProtocol=https;EndpointSuffix=${environment().suffixes.storage};AccountName=${storageAccount.name};AccountKey=${listKeys(storageAccount.id, storageAccount.apiVersion).keys[0].value}'

resource appServicePlan 'Microsoft.Web/serverfarms@2021-03-01' = {
  name: '${name}-plan-linux'
  location: Location
  sku: {
    name: 'Y1'
    tier: 'Dynamic'
  }
  kind: 'linux'
  properties: {
    reserved: true
  }
}

resource azureFunction 'Microsoft.Web/sites@2020-06-01' = {
  name: name
  location: Location
  identity: {
    type: 'SystemAssigned'
  }
  kind: 'functionapp,linux'
  properties: {
    serverFarmId: appServicePlan.id
    siteConfig: {
      appSettings: [
        {
          name: 'AzureWebJobsDashboard'
          value: storageConnectionString
        }
        {
          name: 'AzureWebJobsStorage'
          value: storageConnectionString
        }
        {
          name: 'WEBSITE_CONTENTAZUREFILECONNECTIONSTRING'
          value: storageConnectionString
        }
        {
          name: 'FUNCTIONS_EXTENSION_VERSION'
          value: '~3'
        }
        {
          name: 'APPINSIGHTS_INSTRUMENTATIONKEY'
          value: reference(appInsightsComponents.id, appInsightsComponents.apiVersion).InstrumentationKey
        }
        {
          name: 'FUNCTIONS_WORKER_RUNTIME'
          value: 'dotnet-isolated'
        }
      ]
      linuxFxVersion: 'DOTNET-ISOLATED|5.0'
    }
  }
}

Additional context

• It is not necessary a problem with bicep itself, but there is no real examples of how to do it using Biceps anyway, so any help to do it is appreciated.

[brwilkinson]

The easiest way to get these settings is to go through the portal UI, until you get to the very last page, then click the export template option, you can view the desired settings in the template and template parameters section.

I have a few that I have exported this way, however not the one you are looking for.

once I have exported them I put them in lookup tables with a key to get the options that I want.

https://github.com/brwilkinson/AzureDeploymentFramework/blob/main/ADF/bicep/AppServiceWebSite.bicep#L66

Then depending on the permutations, have some logic to match the correct settings.

https://github.com/brwilkinson/AzureDeploymentFramework/blob/main/ADF/bicep/x.appService.bicep#L98

[dozer75]

@brwilkinson Well, I have done that as well, but it doesn't work for several reasons (e.g. the portal UI doesn't support creating Azure Function with dotnet-isolated).

After I wrote this issue I started to suspect that this may not be a bicep issue, but rather some issues around Azure Function deployment in general for .NET in isolation mode. I have an issue ( Azure/azure-functions-host#8367 ) as well that I created after this one that I more and more suspect is the reason for most of my problems. It may be that there is some issues below bicep that causes this.

[brwilkinson]

I suspect that depends on your App Service plan.

Using an ASE (app service environment) is true isolation, based on having dedicated hardware.

https://docs.microsoft.com/en-us/azure/app-service/environment/creation

[brwilkinson]

Looks like you have some follow up on the other repo, so I will mark this as answered, however if you have anything Bicep related, free to continue the discussion.