Use IWebHostEnvironment in Program.cs web host builder in ASP.NET Core 3.1

Question

I have an ASP.NET Core 3.1 application, and I need to access the IWebHostEnvironment in the Program.cs web host builder. This is what I have right now (Program.cs):

public class Program {

    public static void Main(string[] args) {
        CreateWebHostBuilder(args).Build().Run();
    }

    private static bool IsDevelopment => 
        Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") == "Development";

    public static string HostPort => 
        IsDevelopment 
            ? "5000" 
            : Environment.GetEnvironmentVariable("PORT");

    public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseUrls($"http://+:{HostPort}")
            .UseSerilog((context, config) => {
                config.ReadFrom.Configuration(context.Configuration);
            })
            .UseStartup<Startup>();
}

Instead of doing the IsDevelopment check the way I do it, I would like to use the IsDevelopment() method from IWebHostEnvironment, not entirely sure how to do that. What I have right now works, but honestly it doesn't "feel right".

[CreateDefaultBuilder](https://github.com/dotnet/aspnetcore/blob/1480b998660d2f77d0605376eefab6a83474ce07/src/DefaultBuilder/src/WebHost.cs#L155) is wrapper method which initializes features like --- use Kestrel as the web server and configure it using the application's configuration providers,. If you see the implementation, it injects the hosting environment. If you want to have something similar then you refer the mentioned [code](https://github.com/dotnet/aspnetcore/blob/1480b998660d2f77d0605376eefab6a83474ce07/src/DefaultBuilder/src/WebHost.cs#L155). — user1672994, Sep 28 '20 at 12:52

score 8 · Answer 1 · answered Oct 05 '22 at 15:14

In .NET 6 you can use the new minimal hosting model.

In your main program, you can create an application builder and an application. The Environment (as a IWebHostEnvironment) is available on both objects.

For example in Program.cs:

var builder = WebApplication.CreateBuilder(args);
var environment = builder.Environment;

Or:

var app = builder.Build();
var environment = app.Environment;

You may want to pass the environment to ConfigureServices like this:

var startup = new Startup(builder.Configuration);
startup.ConfigureServices(builder.Services, builder.Environment);

(PS: I don't think this code is dependent on using the minimal hosting model, but that makes it simpler. I think the Environment properties are also available back to .NET 3.1 which is the original question.)

score 4 · Answer 2 · answered Jun 15 '21 at 16:34

If you want to use the IWebHostingEnvironment you should get it from the context parameter of ConfigureAppConfiguration

 public static IHostBuilder CreateHostBuilder(string[] args) =>
            Host.CreateDefaultBuilder(args)
                .ConfigureAppConfiguration((context, builder) =>
                {
                    var isDev = context.HostingEnvironment.IsDevelopment();
                    var isProd = context.HostingEnvironment.IsProduction();
                    var envName = context.HostingEnvironment.EnvironmentName;
                })
                .ConfigureWebHostDefaults(webBuilder =>
                {
                    webBuilder.UseStartup<Startup>();
                });

Use IWebHostEnvironment in Program.cs web host builder in ASP.NET Core 3.1

2 Answers2

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