Calling 'BuildServiceProvider' from application code results in copy of Singleton warning. How do I avoid this?

If called BuildServiceProvider() in ConfigureServices, shown warning "Calling 'BuildServiceProvider' from application code results in a additional copy of Singleton services being created"

I solved this issue:

Create another function (which passed argument is IServiceCollection) and into the function call BuildServiceProvider()

For example your code it should be:

public void ConfigureServices(IServiceCollection services)
{
    if (HostingEnvironment.EnvironmentName == "Local")
    {
        services.AddHealthChecksUI()
        .AddHealthChecks()
        .AddCheck<TestWebApiControllerHealthCheck>("HomePageHealthCheck")
        .AddCheck<DatabaseHealthCheck>("DatabaseHealthCheck");
    }

    services.Configure<PwdrsSettings>(Configuration.GetSection("MySettings"));
    services.AddDbContext<PwdrsContext>(o => o.UseSqlServer(Configuration.GetConnectionString("PwdrsConnectionRoot")));

    services.AddMvc(o =>
    {
        o.Filters.Add<CustomExceptionFilter>();
    });

    services.AddCors(options =>
    {
        options.AddPolicy("CorsPolicy", b => b
            .SetIsOriginAllowed((host) => true)
            .AllowAnyMethod()
            .AllowAnyHeader()
            .AllowCredentials());
    });

    services.AddSwaggerDocument();
    services.AddHttpContextAccessor();

    services.AddAutoMapper(typeof(ObjectMapperProfile));
    services.AddTransient<IEmailSender, EmailSender>();
    services.AddScoped(typeof(IAppLogger<>), typeof(LoggerAdapter<>));
    services.AddScoped(typeof(IAsyncRepository<>), typeof(Repository<>));
    services.AddScoped<IRfReportTypeRepository, RfReportTypeRepository>();
    services.AddScoped<IRfReportRepository, RfReportRepository>();
    services.AddScoped<IRfReportLookupsService, RfReportLookupsService>();
    services.AddScoped<IRfReportService, RfReportService>();

    RegisterSerilogLogger logger = CreateRegisterSerilogLogger(services);
}

private RegisterSerilogLogger CreateRegisterSerilogLogger(IServiceCollection services){
        services.Configure<RAFLogging>(Configuration.GetSection("RAFLogging"));
        ServiceProvider serviceProvider = services.BuildServiceProvider(); //No warning here ))
        IOptions<RAFLogging> RAFLogger = serviceProvider.GetRequiredService<IOptions<RAFLogging>>();
        RegisterSerilogLogger logger = new RegisterSerilogLogger(RAFLogger);
    return logger;
}

Or use ApplicationServices of IApplicationBuilder. ApplicationSerivces's type is IServiceProvider.

I mention this solution is only for remove warning.

Calling BuildServiceProvider creates a second container, which can create torn singletons and cause references to object graphs across multiple containers.

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UPDATED 24.01.2021

I read Adam Freeman's Pro ASP.NET Core 3 8th book. Adam Freeman used app.ApplicationServices instead of services.BuildServiceProvider() in page 157 for this purpose, that app is Configure method's parameter that this method located in Startup.cs

I thinks correct version is to use ApplicationServices property of app, which app is IApplicationBuilder in Configure method's parameter. ApplicationServices's type is IServiceProvider.

Adam Freeman's Pro ASP.NET Core 3 8th book : Pro ASP.NET Core 3

Adam Freeman's example project: SportStore project's Startup.cs, SportStore project's SeedData.cs

Microsoft's recommendations about DI : Dependency injection in ASP.NET Core

Similar questions' answers in Stackoverflow: https://stackoverflow.com/a/56058498/8810311, https://stackoverflow.com/a/56278027/8810311