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

Question

I just pasted the 4 lines at the end from another project and it works but I get a warning.. I clearly do not understand DI well enough ... What does it want me to change ?

  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>();

        services.Configure<RAFLogging>(Configuration.GetSection("RAFLogging"));
        ServiceProvider serviceProvider = services.BuildServiceProvider(); //WARNING IS HERE
        IOptions<RAFLogging> RAFLogger = serviceProvider.GetRequiredService<IOptions<RAFLogging>>();
        RegisterSerilogLogger logger = new RegisterSerilogLogger(RAFLogger);
    }

First, why are you building provider? This might be an [XY problem](https://meta.stackexchange.com/questions/66377/what-is-the-xy-problem). Can you reformat the question so we get a clearer picture of the current problem and what you are **actually** trying to do? — Nkosi, Nov 22 '19 at 18:03
Im not sure. I guess I already have one and perhaps that is creating another ? — punkouter, Nov 22 '19 at 21:45
What do you mean by `WARNING IS HERE`? Please provide details about the warning. Show us the text of the warning. Is this a compiler warning? A warning from some code analysis plugin? If so, which one? Is this a runtime exception? Show us all relevant details of the exception (message, type, stack trace, inner exceptions). — Steven, Nov 24 '19 at 21:37
@punkouter "What does it want me to change": Don't build the service provider manually by invoking`BuildServiceProvider()`. This method should be invoked by Host only once. Duplicate service provider might lead to some unexpected bugs. — itminus, Nov 25 '19 at 02:06
The warning is the title. I guess IServiceCollection is where I should put this logger somehow? I need to understand better IServiceCollection vs. a ServiceProvider. — punkouter, Nov 25 '19 at 14:06
@punkouter Did you read my answer, that I did update it ? https://stackoverflow.com/a/59836362/8810311 — Ramil Aliyev, Jan 30 '21 at 20:41
Ok.. I wish I could remember what I was doing ..its been so long — punkouter, Feb 01 '21 at 15:04

Ramil Aliyev · Accepted Answer · 2021-02-05T16:39:59.917

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.

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

Calling this method from another function is not the right solution. You should avoid calling it from ANYWHERE in your code. This is just removing the warning. — Adys, Feb 19 '20 at 10:26
@Adys I agree with you my friend, I mentioned this solution is remove warning :) I thinks correct version is to call ServiceProvider of app, which app is IApplicationBuilder in Configure method — Ramil Aliyev, Feb 19 '20 at 13:38
I used var serviceProvider = services.BuildServiceProvider(); var logger = serviceProvider.GetService>(); services.AddSingleton(typeof(ILogger), logger); in the function. I was getting an additional singleton warning before — Golden Lion, Dec 10 '21 at 17:10
what is RegisterSerilogLogger? should this be used instead of addSingleton — Golden Lion, Dec 10 '21 at 17:11
for asp core 6 you can use `app.Services` instead of `app.ApplicationServices` — Ahmed Mohammed, May 22 '22 at 19:29

score -2 · Answer 2 · answered Feb 19 '20 at 10:32

-2

The ONLY purpose of calling 'BuildServiceProvider' is to get a service provider instance,

To remove this call and still be able to use IServiceProvider, change Configure method to get it as parameter:

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IServiceProvider provider)

answered Feb 19 '20 at 10:32

Adys

125
1
7

You needn't inject IServiceProvider because app.ApplicationServices is IServiceProvider . – Ramil Aliyev Feb 24 at 11:48 – Ramil Aliyev Feb 28 '20 at 05:42

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

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