IDisposable singleton is selectively disposed at the end of ServiceScope

[Ghostbird]

I have a rather baffling problem with a solution that I don't understand:

• I have a singleton that has an HttpClient.
• Therefore this singleton must implement IDisposable otherwise you'll get an an error that says something like:

  X has disposable members but does not implement IDisposable.

• At some point I temporary create a new ServiceScope because some operations must be done in a tenant scope.
• At the end of that ServiceScope the Singleton is disposed and my app is in an invalid state, every subsequent use of the HttpClient will throw an ObjectDisposedException

Why oh why is a Singleton disposed at the end of a ServiceScope? Shouldn't a Singleton only be disposed when the root serviceprovider is disposed?

Even weirder, now instead of giving this class an HttpClient member, I made it extend HttpClient. Now it's still IDisposable but somehow it magically is not disposed when the ServiceScope ends, but I have no idea why. This solves my problem but feels wrong.

Can someone explain this to me?

[Ghostbird]

I found part of the issue. Somewhere else one of the interfaces implemented by this class was registered using:

services.AddTransient<SomeInterface>(sp => sp.GetRequiredService<MyClass>());

I guess the Dispose method was called when the scope ended, because SomeInterface was transient and the underlying class was IDisposable. That's a bit weird, but somewhat understandable. It still doesn't explain why the problem didn't occur when I made the class extend HttpClient. I thought maybe HttpClient implements IDisposable explicitly, and that prevents the behaviour. But I checked the code, and that's not the case.

I fixed it by changing the AddTransient<SomeInterface> to AddSingleton<SomeInterface>.