Worker Service Error while validating the service descriptor ServiceType

Question

I have a worker service that I wrote in .Net Core 3.1. Here I want to register services in another layer (ICarVerticalLogic and IEmailPdfLogic) in my program.cs, but when I run the project I get the following error.

My Program.cs

 public class Program
    {
        public static void Main(string[] args)
        {
            var startupPath = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule?.FileName);
            var logFilePath = Path.Combine(startupPath, "logs", "logs.txt");

            Log.Logger = new LoggerConfiguration()
                .WriteTo.File(logFilePath, rollingInterval: RollingInterval.Day)
                .CreateLogger();

            CreateHostBuilder(args).Build().Run();
        }

        public static IHostBuilder CreateHostBuilder(string[] args) =>
             Host.CreateDefaultBuilder(args)
                 .UseWindowsService()
                 .ConfigureLogging(logging =>
                 {
                     logging.AddSerilog();
                 })
                 .ConfigureServices((hostContext, services) =>
                 {
                     services.AddSingleton(AutoMapperConfig.CreateMapper());
                     services.AddScoped<ICarVerticalLogic, CarVerticalLogic>();
                     services.AddScoped<IEmailPdfLogic, EmailPdfLogic>();
                     services.AddSingleton(typeof(IConverter), new SynchronizedConverter(new PdfTools()));

                     services.AddEntityFrameworkSqlServer()
                     .AddDbContext<AsamDbContext>(options =>
                     {
                         options.UseMySql(hostContext.Configuration.GetSection("ConnectionString").Value);
                     });
                     services.AddHostedService<Worker>();
                 });
    }

Error :

InvalidOperationException: Error while validating the service descriptor 'ServiceType: Microsoft.Extensions.Hosting.IHostedService Lifetime: Singleton ImplementationType: CarVerticalWorkerService.Worker': Cannot consume scoped service 'Asam.Logic.Infrastructure.ICarVerticalLogic' from singleton 'Microsoft.Extensions.Hosting.IHostedService'.

Answer 1

The worker service is a singleton service by default. And a scoped service instances are bound to request. You can not inject a scoped service into a singleton service.

If you don't mind change the lifetime of ICarVerticalLogic and IEmailPdfLogic service
to Singleton, try to modify your codes:

services.AddScoped<ICarVerticalLogic, CarVerticalLogic>();
services.AddScoped<IEmailPdfLogic, EmailPdfLogic>();

to

services.AddSingleton<ICarVerticalLogic, CarVerticalLogic>();
services.AddSingleton<IEmailPdfLogic, EmailPdfLogic>();

And here's my test result: