azure-functions-durable-extension: Task Hub name must be specified in host.json when using slots

Describe the bug

When I deploy a Durable Functions App to Function App, it said

The function runtime is unable to start. Microsoft.Azure.WebJobs.Extensions.DurableTask: Task Hub name must be specified in host.json when using slots.

Investigative information

Durable Functions extension version: 2.0.0 Function App version (1.0 or 2.0): 2.0 Programming language used: C#

My host.json file content:

{
  "version": "2.0",
  "extensions": {
    "durableTask": {
      "hubName": "%SlotTaskHub%"
    }
  }
}

My settings.json (main slot):

{
  "IsEncrypted": false,
  "Values": {
    "SlotTaskHub": "MainHubName"
  }
}

My settings.json (dev slot):

{
  "IsEncrypted": false,
  "Values": {
    "SlotTaskHub": "DevHubName"
  }
}

My client function:

[FunctionName("MyFunctionName")]
public async Task<HttpResponseMessage> MyFunctionAsync([HttpTrigger(AuthorizationLevel.Anonymous, "POST")]HttpRequestMessage request,
    [DurableClient(TaskHub = "%SlotTaskHub%")]IDurableOrchestrationClient starter)
{
    //My code here
}

Expected behavior Successfully works in both slots with different TaskHub names and the same storage account.

Actual behavior If deployed to the main slot, it works. If deployed to other slots, I receive the error.

Additional context

Development environment (ex. Visual Studio) Visual Studio 2019
Additional bindings used HttpTrigger or ServiceBusTrigger

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 23 (10 by maintainers)

Most upvoted comments

It should also be possible to omit hubName from host.json and set the hub name with an app setting called AzureFunctionsJobHost__extensions__durableTask__hubName. It works in a production slot (can confirm that storage containers are created with the supplied name). However, it’s not working in non-production slots either.

anthonychu on Nov 21, 2019

For reference for anyone who wants to customize configuration, Azure Functions now has a proper way to handle this: https://docs.microsoft.com/en-us/azure/azure-functions/functions-dotnet-dependency-injection#customizing-configuration-sources.

ConnorMcMahon on Nov 18, 2020

@ConnorMcMahon think I’m still seeing this on 2.1.1 and 2.2.0.

I have a host.json with the following contents:

{
  "version": "2.0",
  "extensions": {
    "durableTask": {
      "hubName": "%CustomHubName%"
    }
  }
}

I use the attribute [DurableClient(TaskHub = "%CustomHubName%")]IDurableClient client. I then set the CustomHubName appsetting differently per slot and it does not match the app name but still receive the error.

Task Hub name must be specified in host.json when using slots. Specified name must not equal the default HubName.

In fact even when not using slots, the appsetting or host.json value is never used and it always uses the default task hub name.

I’ve tried using setting AzureFunctionsJobHost__extensions__durableTask__hubName with and without a value in the host.json too but still it uses the default.

I’ve also tried putting a hardcoded value in the host.json instead of an appsetting and again it still uses the default.

Note: it works as expected locally, but when deployed to an Azure Function (v3) it doesn’t.

jjcollinge on Mar 29, 2020

I’m also facing the same issue with different versions from 2.0.0 to 2.2.1 and azure function V3 and .Net Core 3.1 But when I’ve changed my function to V2 it fixed the issue for me.
I think the issue should be reopened, but I hope my workaround can help someone for who is not critical to use V3

romantitov on Apr 28, 2020

function app name : rclfunctions - staging (staging slot)

App Insights is not set up for the function app. Do I need to set it up for you to diagnose?

anilripla on Mar 10, 2020

Just to be clear, I am specifying the TaskHub in my host.json but I am getting the same error message as the author so I was wondering if I also need it as an app setting and configured in the trigger.

The function runtime is unable to start. Microsoft.Azure.WebJobs.Extensions.DurableTask: Task Hub name must be specified in host.json when using slots.

Right now I am just throwing darts at the wall trying to get my slots working.

mpaul31 on Dec 3, 2019