How to instanciate ServiceCollection and use IHttpCientFactory in a .NET Core ConsoleApp?

Question

i have the following code, and when Running this code i can validate that the Client is created in the ConfigureService Method, when ConfigureServices are called.

1. Main Question: How can i get the access to clientFactory in the MainAsync Task?
2. Secondary Priority: How do i instanciate the serviceColletion through a constructor

namespace CustomeNameSpace
{
  public class Program
  {
    public static IConfigurationRoot configuration;
    private static readonly IServiceCollection serviceCollection;

    public static void Main(string[] args)
    {
      ConfigureServices();
      ILogger logger = NullLogger.Instance;
      MainAsync(logger).GetAwaiter().GetResult();
    }

    private static async Task MainAsync(ILogger log) 
    {
      // Need to use httpClientAt this location....
      // var clientFactory = .....
      // var client = clientFactory.CreateClient()
    }

    public static void ConfigureServices()
    {
      var serviceCollection = new ServiceCollection();
      serviceCollection.AddHttpClient();

      var clientFactory = serviceCollection.BuildServiceProvider().GetRequiredService<IHttpClientFactory>();
      //var client = clientFactory.CreateClient();

      configuration = new ConfigurationBuilder().SetBasePath(Directory.GetParent(AppContext.BaseDirectory).FullName)
        .AddJsonFile("local.settings.json", false)
        .Build();
    }
  }
}

Answer 1

This code needs to be refactored to follow a more stream lined approach to applying dependency injection.

public class Program {

    //async Task Main feature allowed from C# 7.1+
    public static async Task Main(string[] args) {
        //Composition root
        IServiceProvider services = ConfigureServices();
        
        ILogger logger = NullLogger.Instance;
        
        IHttpClientFactory clientFactory = service.GetRequiredService<IHttpClientFactory>();
        HttpClient client = clientFactory.CreateClient();
        
        IConfiguration configuration = service.GetRequiredService<IConfiguration>();
        
        await RunAsync(logger, client, configuration);
    }

    private static async Task RunAsync(ILogger log, HttpClient client, IConfiguration configuration) {
      
      //...
      
    }

    public static IServiceProvider ConfigureServices() {
        IServiceCollection services = new ServiceCollection();
        services.AddHttpClient();

        IConfigurationRoot configuration = new ConfigurationBuilder()
            .SetBasePath(Directory.GetParent(AppContext.BaseDirectory).FullName)
            .AddJsonFile("local.settings.json", false)
            .Build();
        services.AddSingleton<IConfigurationRoot>(configuration);
        services.AddSingleton<IConfiguration>(configuration);
        
        return services.BuildServiceProvider();
    }
}

Note how any required services can now be resolved and used as needed from the service provider.

This could be further improved by encapsulating the primary functionality in a class and resolving it from the service provider so that all explicit dependencies can be resolved and injected directly by the service container.