How to get an ILogger from an Activity Function?

Question

I am using Durable Azure Function in a prototype for a future project.

Basically, I have a Client Azure Function triggered by an HTTP POST request that starts the Orchestrator. Then, the Orchestrator decides to trigger an Activity. Nothing complicated.

Here is a sample of what I am doing:

[FunctionName("ClientFunction")]
public static async Task<HttpResponseMessage> OnHttpTriggerAsync([HttpTrigger(AuthorizationLevel.Anonymous, "post")]
            HttpRequestMessage request, [OrchestrationClient] DurableOrchestrationClient starter, ILogger logger)
{
    // Triggers the orchestrator.
    string instanceId = await starter.StartNewAsync("OrchestratorFunction", null);

    return new HttpResponseMessage(HttpStatusCode.OK);
}


[FunctionName("OrchestratorFunction")]
public static async Task DoOrchestrationThingsAsync([OrchestrationTrigger] DurableOrchestrationContext context, ILogger logger)
{
    // Triggers some serious activity.
    await context.CallActivityAsync("ActivityFunction", null);
}

[FunctionName("ActivityFunction")]
public static Task DoAnAwesomeActivity([ActivityTrigger] DurableActivityContext context)
{
    // Short & Sweet activity...
    // Wait... Where's my logger?
}

Both the Orchestrator and the Client Functions are being given an ILogger but not the Activity Function; as stated in the documentation (either a specific parameter or the DurableActivityContext instance), the Activity function only gets one parameter. And I am not under the impression that the static class in which these methods are declared could keep a reference on that ILogger.

I understand that the Activity Function should perform one small job but I would be more comfortable if I was able to log that the activity was called with the appropriate values if something goes wrong (and it will :) ).

Question

How can the Activity access the ILogger?

What goes wrong if you put ILogger in the method signature of Activity Function? There should be no restriction on using ILogger in Activity and I didn't see any error on my side either. — Jerry Liu
I did not test it because of this specific comment: "It is not possible to pass multiple parameters to an activity function directly." I assumed it was either my custom parameter or the DurableActivityContext ... Will try it as soon as I get back to work! :) — Kzrystof

Jerry Liu Jerry Liu · Accepted Answer · 2019-02-09T17:18:30

It is not possible to pass multiple parameters to an activity function directly. The recommendation in this case is to pass in an array of objects or to use ValueTuples objects in .NET.

This restriction you are concerned about is talking about the parameters we pass from Orchestrator to Activity Function. It doesn't mean we could only use one parameter in Activity method signature. Feel free to add ILogger there and complete your job as needed.

How to get an ILogger from an Activity Function?

1 Answers