Enable to pass an existing IServiceCollection (#1060).

[kaztechSolutions]

Allow to pass an existing IServiceCollection instance to WebHostBuilder which should be used instead of creating a new one inside WebHostBuilder. Could be a solution to issue #1060.

[dnfclas]

All CLA requirements met.

[davidfowl]

I'm not 100% certain I like this. The caveats here are that the service collection cannot be modified after the it is give to the web host. That's not clear from the method that this is the case.

Also, why is it a Func<IServiceCollection> instead of just an IServiceCollection

[kaztechSolutions]

The caveats here are that the service collection cannot be modified after the it is give to the web host

I see your point. But the main issue here is that WebHostBuilder is passing the serviceProvider to WebHost to do service location. Of course this is not easy to change but therefore its the serviceCollection's last stop.

That's not clear from the method that this is the case.

Maybe it is enough to just change the methods name to for example BuildServiceCollection?

Also, why is it a Func instead of just an IServiceCollection

I also thought about that after my pull request. My first intention was to be able to create the ServiceCollection as late as possible. But you are right, maybe it is just simpler to pass an IServiceCollection.

[davidfowl]

Take a look at 6b095cf and see if you still need this feature. I don't think you do but I don't understand your scenario enough to make that call.

[davidfowl]

Closing this out. If you can't make the change above work I'd like to understand why