CODEWITHSUNDEEP
asp.netasp.net-coreasp.net-core-mvckestrel-http-server
severin
severin

Reputation: 5493

Read environment variables in ASP.NET Core

Running my ASP.NET Core application using DNX, I was able to set environment variables from the command line and then run it like this:

set ASPNET_ENV = Production
dnx web

Using the same approach in 1.0:

set ASPNETCORE_ENVIRONMENT = Production
dotnet run

does not work - the application does not seem to be able to read environment variables.

Console.WriteLine(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT"));

returns null

What am I missing?

Upvotes: 114

Views: 187951

Answers (4)

MC9000
MC9000

Reputation: 2403

You can't read any environment variables from an asp.net core app running on IIS anymore since Win2012R2 Server. I believe this was intentional.

Upvotes: 0

Umer Waheed
Umer Waheed

Reputation: 4574

If you create the Environment variables at runtime during development then you will get null every time. You have to restart the visual studio because VS read EV at startup only.

Upvotes: 7

Dmitry
Dmitry

Reputation: 16795

Your problem is spaces around =.

This will work (attention to space before closing quote):

Console.WriteLine(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT "));

The space after ASPNETCORE_ENVIRONMENT in this code is not a typo! The problem in the question was having extra space (in SET...), so you must use the same space in GetEnvironmentVariable().

As noted by Isantipov in a comment, an even better solution is to remove the spaces entirely from the SET command:

set ASPNETCORE_ENVIRONMENT=Production

Upvotes: 186

Isantipov
Isantipov

Reputation: 20909

This should really be a comment to this answer by @Dmitry (but it is too long, hence I post it as a separate answer):

You wouldn't want to use 'ASPNETCORE_ENVIRONMENT ' (with a trailing space) - there are features in ASP.NET Core which depend on the value of 'ASPNETCORE_ENVIRONMENT'(no trailing space) - e.g. resolving of appsettings.Development.json vs appsettings.Production.json. (e.g. see Working with multiple environments documentation article

And also I guess if you'd like to stay purely inside ASP.NET Core paradigm, you'd want to use IHostingEnvironment.Environment(see documentation) property instead of reading from Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") directly (although the former is of course set from the latter). E.g. in Startup.cs

public class Startup
{
    //<...>

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        Console.WriteLine("HostingEnvironmentName: '{0}'", env.EnvironmentName);
        //<...>
    }

    //<...>
}

Upvotes: 30

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