读取 ASP.NET 核心中的环境变量

使用 DNX运行我的 ASP.NET Core 应用程序，我能够从命令行设置环境变量，然后像这样运行它:

set ASPNET_ENV = Production
dnx web

在1.0中使用相同的方法:

set ASPNETCORE_ENVIRONMENT = Production
dotnet run

不工作-应用程序似乎不能读取环境变量。

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

返回 null

我错过了什么？

138643 次浏览
小开
最佳答案

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
小开

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);
//<...>
}


//<...>
}
小开

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.


提交答案