How can an azure v4 serverless function return a response on the root?

Question

A c# odata serverless function (isolated model) needs to return a manifest at the root. I replaced the api prefix with "" in the host.json file but when I try Route="" the application returns the standard 'your application is ready' response at the root. How can I override this behaviour?

Answer 1

You can use Route="{ignored:maxlength(0)?}" to return the response at the root endpoint.

Thanks for the insights bredd.

I have created a C# OData isolated Azure function and able to return the response on the root.

function.cs:

[Function("GetProducts")]
public async Task<HttpResponseData> GetProducts([HttpTrigger(AuthorizationLevel.Function, "get","post", Route = "{ignored:maxlength(0)?}")] HttpRequestData req, string ignored = "")
{

var response = req.CreateResponse(HttpStatusCode.OK);
    var manifest = new
    {
        name = "My OData Service",
        version = "1.0.0",
        description = "This is the manifest for my OData service."
    };

    await response.WriteAsJsonAsync(manifest);
    return response;
}

Program.cs:

var host = new HostBuilder()
    .ConfigureFunctionsWebApplication()
   .ConfigureFunctionsWorkerDefaults()
    .ConfigureServices(services =>
    {
        services.AddControllers()
            .AddOData(options => options.Select()
       .Filter()
       .OrderBy()
       .Count()
       .Expand()
       .SetMaxTop(100)
       .AddRouteComponents("odata", GetEdmModel()));
    })
    .Build();

host.Run();
IEdmModel GetEdmModel()
{
    var builder = new ODataConventionModelBuilder();
    builder.EntitySet<Products>("Products");
    return builder.GetEdmModel();
}

host.json:

 "extensions": {
   "http": {
     "routePrefix": ""
   }
 }

Console Output:

Functions:

        GetProducts: [GET,POST] http://localhost:7220/{ignored:maxlength(0)?}

For detailed output, run func with --verbose flag.
[2025-01-03T13:45:16.568Z] Executing 'Functions.GetProducts' (Reason='This function was programmatically called via the host APIs.', Id=d72799f9-72f5-49c1-8f3e-95fb7461d930)
[2025-01-03T13:45:18.335Z] Host lock lease acquired by instance ID '000000000000000000000000F72731CC'.
[2025-01-03T13:45:21.906Z] Executed 'Functions.GetProducts' (Succeeded, Id=d72799f9-72f5-49c1-8f3e-95fb7461d930, Duration=5418ms)

Response: