WebForms dependency resolution.

DependencyResolution.cs

  public static class DependencyResolution {
    public static void ConfigureServices(IContainer container = null, ServiceCollection services = null) {
      container = container ?? new Container();
      services = services ?? new ServiceCollection();

      container.Populate(services);
      var provider = container.GetInstance<IServiceProvider>();
      HttpRuntime.WebObjectActivator = new HttpRequestScopedServiceProvider(provider);
    }

    private class HttpRequestScopedServiceProvider : IServiceProvider {
      private static readonly BindingFlags Flags = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.CreateInstance;

      private readonly IServiceProvider provider;

      public HttpRequestScopedServiceProvider(IServiceProvider provider) {
        this.provider = provider;
      }

      public object GetService(Type serviceType) {
        var scope = ScopeKeeper.GetScope();

        if(scope == null) {
          scope = provider.CreateScope();
          ScopeKeeper.SetScope(scope);
        }

        try {
          return ActivatorUtilities.GetServiceOrCreateInstance(scope.ServiceProvider, serviceType);
        } catch(InvalidOperationException) {
          return Activator.CreateInstance(serviceType, Flags, null, null, null);
        }
      }

      private static class ScopeKeeper {
        private static HttpContext Context => HttpContext.Current;

        public static IServiceScope GetScope() {
          return Context?.Items[typeof(IServiceScope)] as IServiceScope;
        }

        public static void SetScope(IServiceScope scope) {
          if(Context != null) {
            void DisposeScope(object sender, EventArgs args) {
              if(sender is HttpApplication application) {
                application.RequestCompleted -= DisposeScope;
                scope.Dispose();
              }
            }

            Context.Items.Add(typeof(IServiceScope), scope);
            Context.ApplicationInstance.RequestCompleted += DisposeScope;
          }
        }
      }
    }
  }