Obsolete WebHostBuilder

[Tratcher]

WebHostBuilder was replaced by HostBuilder in 3.0. In 5.0 we should consider obsoleting the old one.

[analogrelay]

To clarify even more, the idea here is to obsolete the types and public APIs on:

• WebHost
• WebHostBuilder
• Add an "obsolete" banner to https://docs.microsoft.com/en-us/aspnet/core/fundamentals/host/web-host?view=aspnetcore-3.1

The obsolete message should include an aka.ms link that points to https://docs.microsoft.com/en-us/aspnet/core/fundamentals/host/generic-host?view=aspnetcore-3.1#settings-for-web-apps

[davidfowl]

We shouldn’t do this until we resolve the remaining gaps that people complain about:

• Passing extra state to the startup class (for e.g)

[Tratcher]

• Passing extra state to the startup class

Related issue: #19809

[davidfowl]

Also the IStartup replacement.

[BrennanConroy]

Lets start cleaning up areas before obsoleting this starting in preview6.

• SignalR - [SignalR] Move to generic host #22602
• DataProtection Move DataProtection tests to HostBuilder #24254
• Middleware - [Middleware] Move to GenericHost #23626
  • Rewrite
  • Localization
  • Localization.Routing
  • StaticFiles
  • HttpsPolicy
  • HttpOverrides
  • WebSockets
  • Diagnostics
  • HostFiltering
  • ResponseCaching
  • Session
  • HealthChecks
  • CORS
  • Diagnostics.EntityFrameworkCore
  • MiddlewareAnalysis
  • ResponseCompression
  • ConcurrencyLimiter
  • NodeServices
  • HeaderPropagation
• Kestrel [Kestrel] Move to GenericHost #24279
• IIS [IIS] Move to GenericHost #24280
• Routing [Routing] Move to GenericHost #24281
• Security
  • Authentication Switch to new host apis #23783
  • CookiePolicy [Security] Move to GenericHost #24282
• Identity Switch to new host apis #23783
• Azure [Azure] Move to GenericHost #24283
• MVC
• MusicStore [MusicStore] Move to GenericHost #24284
• HttpSys [HttpSys] Move to GenericHost #24285
• Hosting [Hosting] Move to GenericHost #24297

[BrennanConroy]

Example changes #23626

Make sure to dispose the IHost.

Common changes:

Before:

var host = new WebHostBuilder()
    .Configure(app =>
    {
        //...
    }).Build();

After:

using var host = new HostBuilder()
    .ConfigureWebHost(webHostBuilder =>
    {
        webHostBuilder
        .Configure(app =>
        {
            //...
        }
    }).Build();

TestServer:
Before:

var builder = new WebHostBuilder();
var server = new TestServer(builder);

After:

using var host = new HostBuilder()
    // ...
    .UseTestServer()
    .Build();
var server = host.GetTestServer();
await host.StartAsync(); // new TestServer(builder); used to run Start, but we don't use that anymore

[BrennanConroy]

@mkArtakMSFT Can you find some folks to handle MVC?
@HaoK Can you take care of Identity/Security?

Read previous comment for some helpers.

[HaoK]

Yup I can do identity/security

[davidfowl]

Just to be clear, we're not obsoleting anything in 5.0 😄. We haven't scheduled the linked items though I am supportive of updating the other projects.

[HaoK]

How bad is it if the host doesn't get disposed? There's a bunch of tests that rely on a helper method that creates the server, which if the helper has a using var host, the host gets disposed and the test code fails due to object disposed.

i.e.

   Task<TestServer> CreateServer() { 
      using var host = ... .Build(); 
      await host.StartAsync();
      return host.GetTestServer();

[BrennanConroy]

You'll get hangs because by default the console lifetime service is hooked up which waits for ctrl-c (or dispose) before closing.

I changed a bunch of helpers in middleware to return IHost instead of TestServer.

[HaoK]

Hangs? Everything seems to work fine if I just drop the using

[HaoK]

meaning the tests complete just fine without the using

[BrennanConroy]

Yeah, I'm not sure how VS handles that, but when running from command line you should see hangs.

[HaoK]

I just tried via dotnet test and it 'worked'. Does that mean its ok?

[Tratcher]

@BrennanConroy the other thing we should consider is having UseTestServer register its own lifetime to replace ConsoleLifetime. The implementation should be a no-op.

[ghost]

Thanks for contacting us.
We're moving this issue to the Next sprint planning milestone for future evaluation / consideration. We will evaluate the request when we are planning the work for the next milestone. To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[ghost]

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. 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.