Issue with BuildServiceProvider() in ConfigureServices()

When setting up the database in the ConfigureServices() function there’s a warning that says:

Calling ‘BuildServiceProvider’ from application code results in an additional copy of singleton services being created. Consider alternatives such as dependency injecting services as parameters to ‘Configure’.

Steps to reproduce

Here’s following the piece of code that’s references to that warning:

services.AddEntityFrameworkNpgsql()
    .AddDbContext<AppDbContext>(options =>
   options.UseNpgsql(Configuration.GetConnectionString(EnvironmentContants.ConnectionString)))
    .BuildServiceProvider();

Further technical details

EF Core version: 3.0 Database provider: PostgreSQL Target framework: .NET Core 3.0 Operating system: Windows 10 x64 IDE: Visual Studio 2019 16.3.1

Is there any way to fix it?

[Smoothjedi]

I’m also getting this message when attempting to use AddSwaggerGen:

services.AddSwaggerGen((options) =>
{
	var provider = services.BuildServiceProvider().GetRequiredService<IApiVersionDescriptionProvider>();
	...
}

All the documentation/examples I’ve seen for this online uses this code. Is there now a better way to do it?

[davidfowl]

You can suppress the warning in that case. It’s an anti pattern in general. You can do it if you understand what exactly is happening and if you’re ok with it but there’s no support for building the container while trying to build it. What I mean is you have 2 containers and one of them will never be disposed.

PS: it was always an issue, we just warn you about it in 3.0