Can durable functions have multiple triggers?

Question

I have a durable function that is triggered once a day by a Timer Trigger:

[FunctionName("MyDurableFunction")]
public static async Task Run(
    [TimerTrigger("0 0 23 * * *", RunOnStartup = false)] TimerInfo myTimer,
    [OrchestrationClient] DurableOrchestrationClient starter,
    ILogger log)
{
    await starter.StartNewAsync("OrchestrationFunction", null);
}

[FunctionName("OrchestrationFunction")]
public static async Task OrchestrationFunction(
    [OrchestrationTrigger]DurableOrchestrationContext context,
    ILogger log)
{
    // do stuff
}

This works fine. For testing purposes I would also like to be able to trigger the durable function via a Http Trigger, so I added this:

[FunctionName("MyDurableFunctionHttpTrigger")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = "demo")]HttpRequest req, 
    [OrchestrationClient] DurableOrchestrationClient starter, 
    ILogger log)
{
    await starter.StartNewAsync("OrchestrationFunction", null);
    return new OkObjectResult("blah");
}

Running these locally, including either the http trigger or the timer trigger will trigger the function, but including both in the class means that neither trigger events will occur. Is it possible to have multiple trigger types start an orchestration trigger?

Murray Foxcroft · Accepted Answer · 2019-02-14T12:29:39.553

3

I believe you can only have one trigger type per function but can suggest you write all your logic in to a separate project/assembly and then just reference the assembly and call the entry point via parameters, keeping your function implementation clean and simple and centralising the execution logic in another project (or classes within the same project).

On your code, you should have Orchestrator and Activity functions, so you could write one Activity function to do the work and call it from two orchestrators. The guidance on Durable Functions is to keep the orchestrator clean and simple managing just that - the orchestration, offloading the work to the Activities.

I recommend you look at the durable monitor pattern for your timer based requirement and look at the HTTP APIs for HTTP Triggers.

edited Feb 14 '19 at 12:29

answered Feb 14 '19 at 12:23

Murray Foxcroft

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Thanks for that. Would be interesting to know what the technical restriction is, I can't think of any conceptual reason why an orchestrator function couldn't have multiple triggers. – Aidan Feb 15 '19 at 13:10
I cant think of any technical reason either (beyond adding a little additional complexity). – Murray Foxcroft Feb 15 '19 at 13:16

score 1 · Answer 2 · answered Oct 02 '19 at 07:19

What you could do is create multiple normal functions, one for each type of trigger. A scheduled trigger, http trigger, blob trigger, or any other supported trigger.

Within that function you can start a new orchestration function. That orchestration function does not require a trigger in itself. You only need the DurableOrchestrationContext.

public static async Task<object> RunOrchestrator(
    [OrchestrationTrigger] DurableOrchestrationContext context,
    ILogger log)
{
    // orchestration logic here
}

[FunctionName("Info_HttpStart1")]
public static async Task<HttpResponseMessage> HttpStart(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "starter1")]HttpRequestMessage req,
    [OrchestrationClient]DurableOrchestrationClient starter,
    ILogger log)
{
    // Function input comes from the request content.
    string instanceId = await starter.StartNewAsync("Info", null);

    log.LogInformation($"Started orchestration with ID = '{instanceId}'.");

    return starter.CreateCheckStatusResponse(req, instanceId);
}

[FunctionName("Info_HttpStart2")]
public static async Task<HttpResponseMessage> HttpStart(
    [HttpTrigger(AuthorizationLevel.Anonymous, "get", Route = "starter2")]HttpRequestMessage req,
    [OrchestrationClient]DurableOrchestrationClient starter,
    ILogger log)
{
    // Function input comes from the request content.
    string instanceId = await starter.StartNewAsync("Info", null);

    log.LogInformation($"Started orchestration with ID = '{instanceId}'.");

    return starter.CreateCheckStatusResponse(req, instanceId);
}

Can durable functions have multiple triggers?

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