How to add configuration in .NET 6 Program.cs only?

Question

On an AspNetCore 5 Web and API Projects I had the following on Program files:

  public class Program {

    private static IConfiguration Configuration { get; } = new ConfigurationBuilder()
      .SetBasePath(Directory.GetCurrentDirectory())
      .AddJsonFile("settings.json", false, true)
      .AddJsonFile($"settings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT")}.json", false, true)
      .AddEnvironmentVariables()
      .Build();

    public static Int32 Main(String[] args) {

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

    }

    public static IHostBuilder CreateHostBuilder(String[] args) {

      IHostBuilder builder = Host.CreateDefaultBuilder(args);
        
      builder
        .UseSerilog()
        .ConfigureWebHostDefaults(builder => {
          builder
            .UseConfiguration(Configuration)
            .UseStartup<Startup>();
        });

      return builder;  
      
    }
  
  }

Now I am moving this code to NET 6 using Program.cs without Startup.cs :

WebApplicationBuilder builder = WebApplication.CreateBuilder();

builder.Configuration
  .SetBasePath(Directory.GetCurrentDirectory())
  .AddJsonFile("settings.json", false, true)
  .AddJsonFile($"settings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT")}.json", false, true)
  .AddEnvironmentVariables();

builder.Host.UseSerilog();

builder.Host.ConfigureWebHostDefaults(x => { 
  x.UseSerilog(); / ??
  x.UseConfiguration(??); // ??
  x.UseWebRoot("webroot"); 
});

await using WebApplication application = builder.Build();

Question

1. Can I set configuration in builder.Configuration or should I do it inside ConfigureWebHostDefaults?

2. Should I use builder.Host.UserSerilog or add Serilog in ConfigureWebHostDefaults ?

It's a bit confusing because I can do things in different ways.

Answer 1

The new hosting model uses WebApplicationBuilder to configure the web-host defaults, so there's no need for you to call this yourself.

Can I set configuration in builder.Configuration or should I do it inside ConfigureWebHostDefaults ?

Do this using builder.Configuration .

Should I use builder.Host.UserSerilog or add Serilog in ConfigureWebHostDefaults ?

Do this using builder.Host . Nicholas Blumhardt demonstrates this in Setting up Serilog in .NET 6 .

It's a bit confusing because I can do things in different ways.

There's a strong need for backwards compatibility, especially as .NET 6 apps aren't required to use the new hosting model. This results in a few different approaches being available to you. I expect this is something that will change with future releases, but that's merely speculation on my part.

Answer 2

1. Can I set configuration in builder.Configuration or should I do it inside ConfigureWebHostDefaults ?

To manage configuration you should use ConfigurationManager exposed by builder.Configuration :

builder.Configuration
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("settings.json", false, true)
    .AddJsonFile($"settings.{Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT")}.json", false, true)
    .AddEnvironmentVariables();

2. Should I use builder.Host.UserSerilog or add Serilog in ConfigureWebHostDefaults

From Nicholas Blumhardt's (one of the Serilog maintainers) github sample use builder.Host :

builder.Host.UseSerilog((ctx, lc) => // Serilog setup here, use ctx.Configuration for config);