using System;

using System.Linq;

using System.Collections.Generic;

using System.Threading.Tasks;

using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Configuration;

​

public class Program

{

    public static IConfiguration Configuration

    {

        get;

        set;

    }

​

    public static async Task Main()

    {

        Configuration = new ConfigurationBuilder().Build();

        var collection = new ServiceCollection();

        collection.AddSingleton<IConfiguration>(Configuration);

        collection

            .AddHttpClient("TenantsService")

            .AddTypedClient<ITenantProvider>(c => 

                                             new TenantProvider(new TenantProviderSettings

                                            {

                                                 AccessKey = "THE KEY", // Configuration["TenantsService:ApiKey"], 

                                                 BaseUrl = new Uri("https://the-uri-you-need.com") // new Uri(Configuration["TenantsService:Url"])

                                             }, c));

        // build a temporary service provider before.

        var tempServiceProvider = collection.BuildServiceProvider();

        // resolver the tenant service and query for tenants

        var tenantsToRegister = await tempServiceProvider.GetRequiredService<ITenantProvider>().GetAsync();

        // register needed tenants

        foreach (var tenant in tenantsToRegister)

        {

            collection.AddScoped<IGraphQLServer, GraphQLServer>();

        }

​

        using (var scope = collection.BuildServiceProvider().CreateScope())

        {

            var sp = scope.ServiceProvider;

            var servers = sp.GetServices<IGraphQLServer>();

            Console.WriteLine("Registered servers: {0}", servers.Count());

        }

    }

​

    public interface ITenantProvider

    {

        Task<IEnumerable<string>> GetAsync();

    }

​

    public class TenantProvider : ITenantProvider

    {

        public TenantProvider(TenantProviderSettings settings, System.Net.Http.HttpClient client)

        {

        }

​

        public Task<IEnumerable<string>> GetAsync()

        {

            // Do the query http client call here:

            return Task.FromResult<IEnumerable<string>>(

                new[]

                {

                    "Tenant1", 

                    "Tenant2"

                });

        }

    }

​

    public class TenantProviderSettings

    {

        public string AccessKey

        {

            get;

            set;

        }

​

        public Uri BaseUrl

        {

            get;

            set;

        }

    }

​

    public interface IGraphQLServer

    {

    }

​

    public class GraphQLServer : IGraphQLServer

    {

    }

}