Access environment name in Program.Main in ASP.NET Core

Question

Using ASP.NET Mvc Core I needed to set my development environment to use https, so I added the below to the Main method in Program.cs:

var host = new WebHostBuilder()
                .UseContentRoot(Directory.GetCurrentDirectory())
                .UseIISIntegration()
                .UseStartup<Startup>()
                .UseKestrel(cfg => cfg.UseHttps("ssl-dev.pfx", "Password"))
                .UseUrls("https://localhost:5000")
                .UseApplicationInsights()
                .Build();
                host.Run();

How can I access the hosting environment here so that I can conditionally set the protocol/port number/certificate?

Ideally, I would just use the CLI to manipulate my hosting environment like so:

dotnet run --server.urls https://localhost:5000 --cert ssl-dev.pfx password

but there doesn't seem to be way to use a certificate from the command line.

Synapse

Answer 1

I think the easiest solution is to read the value from the ASPNETCORE_ENVIRONMENT environment variable and compare it with Environments.Development:

var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT");
var isDevelopment = environment == Environments.Development;

---

.NET 6 or higher

Starting from .NET 6 using the new application bootstrapping model you can access the environment from the application builder:

var builder = WebApplication.CreateBuilder(args);
var isDevelopment = builder.Environment.IsDevelopment();

Fourscore

Note that in .NET Core 3.0+, the EnvironmentName class is marked as obsolete (learn.microsoft.com/en-us/dotnet/api/…), with the recommendation you switch to the Environments class (learn.microsoft.com/en-us/dotnet/api/…). – Caloric

This only works when environment is set by the environment variable. It's also possible to set it from the command line with --environment "Development" for example – Recitation

How would you do this if you're not using asp.net at all? Like if it's just a console app? – Shrunken

Been searching the internet for this for an hour or so now and just found this simple solution! Thanks so much! I needed this for EF method override of OnConfiguring(DbContextOptionsBuilder optionsBuilder) – Microgamete

Answer 2

[New Answer using ASP 6.0 minimal API]:

If you are using ASP 6.0 minimal API it's very simple by using WebApplication.Environment:

var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();

if (!app.Environment.IsProduction())
{
    // ...
}

app.MapGet("/", () => "Hello World!");

app.Run();

======================================

[Old Answer]

This is my solution (written for ASP.NET Core 2.1):

public static void Main(string[] args)
{
    var host = CreateWebHostBuilder(args).Build();

    using (var scope = host.Services.CreateScope())
    {
        var services = scope.ServiceProvider;
        var hostingEnvironment = services.GetService<IHostingEnvironment>();
        
        if (!hostingEnvironment.IsProduction())
           SeedData.Initialize();
    }

    host.Run();
}

Gramnegative

The problem with this is it creates an entire instance of the application and destroys it again just to get the Environment name. Very heavy handed. – Filariasis

@steed given that this is a clean way to get the IHostingEnvironment and it is only done once before Run() I would say it's neglectable if it's a bit "heavy handed". – Lemkul

Need access to it before web host builder Build is caleld – Naturalism

@Filariasis util you don't call Run, as in CreateHostBuilder(args).Build().Run(), you aren't really creating the entire instance of the application, you just created the host, and requested an instance of IHostingEnvironment – Aunt

IHostingEnvironment has been deprecated and can be replaced with Microsoft.AspNetCore.Hosting.IWebHostEnvironment or Microsoft.Extensions.Hosting.IHostEnvironment – Disapprobation

Not sure about previous versions, but in .NET7, as soon as I call CreateBuilder, I seem to have access to builder.Environment.EnvironmentName. This is before ever calling builder.Build(). – Themis

Answer 3

In .NET core 3.0

using System;
using Microsoft.Extensions.Hosting;

then

var isDevelopment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") == Environments.Development;

Acupuncture

Answer 4

Most answers here use some form of built-in function to determine whether or not the environment is development or not. .NET Core has 3 built-in environment names: Development, Staging and Production.

However, it's possible to specify other names as well. For example, you may have a "QA" environment and want to use that name. Or you may have more than just the three environments.

That's why I think a better approach is to inject the IWebHostEnvironment instance (if possible) and IWebHostEnvironment.EnvironmentName instead.

Croton

Answer 5

In .Net 8 program.cs just call:

builder.Environment.EnvironmentName

Chanson