Hosted services start later with minimal API

I’ve found another problem with the new minimal API introduced in .NET 6 which I haven’t seen announced. Hosting services appear to start later than they did before. Here’s a sample application which demonstrates the problem:

WebApplication1.zip

Program.cs

using Microsoft.AspNetCore.Mvc;

Host.CreateDefaultBuilder(args)
    .ConfigureWebHostDefaults(builder => {
        builder.ConfigureServices((context, services) => services.AddServices())
            .Configure(app => app.UseMiddleware());
    })
    .Build()
    .Run();

//var builder = WebApplication.CreateBuilder(args);

//// Add services to the container.
//builder.Services.AddServices();

//var app = builder.Build();

//app.UseMiddleware();

//app.Run();

public static class ServiceCollectionExtensions {
    public static IServiceCollection AddServices(this IServiceCollection services) {
        services.AddOptions<MvcOptions>().Configure(options => {

        });
        services.AddHostedService<TestHostedService>();
        services.AddControllers();

        return services;
    }
}

public static class ApplicationBuilderExtensions {
    public static IApplicationBuilder UseMiddleware(this IApplicationBuilder app) {
        return app.UseRouting()
            .UseEndpoints(endpoints => endpoints.MapControllers());
    }
}

public class TestHostedService : IHostedService {
    public Task StartAsync(CancellationToken cancellationToken) {
        return Task.CompletedTask;
    }

    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
}

If you put a breakpoint between the Configure callback (line 25) and the hosted service StartAsync method (line 43) and run the application you will see that the StartAsync method runs first. However if you comment out the old startup code (lines 3 to 9) and un-comment the new code (lines 11 to 20) you will notice the breakpoints are hit the other way around. This causes a problem to me as I need the hosted service to run first. Is there a way to fix this using the minimal API?

[msftbot[bot]]

Thanks for contacting us. We’re moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. Because it’s not immediately obvious that this is a bug in our framework, we would like to keep this around to collect more feedback, which can later help us determine the impact of it. We will re-evaluate this issue, during our next planning meeting(s). If we later determine, that the issue has no community involvement, or it’s very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[mitchdenny]

OK great. I’m going to go ahead and close this. Whilst this is a change from the previous hosting model I think that this represents the best approach for folks that need to perf actions synchronously before the application actually starts.

I always thought that folks using hosted services to race to do things before the app starts vs. just invoking the specific operation you want to do was unnecessary complexity.