How to set aspnetcore_environment in publish file?

Question

I have ASP.NET Core application (Web Api). The documentation has explained working with multiple environments, however it failed to explain how to set aspnetcore_environment when publishing the web site.

So lets say if i have 3 environments Development, Staging and Production

1. In classic ASP.NET Web Application i used to create 3 build configurations. Development, Staging and Production ( Like shown in picture below). and then 3 .pubxml files, one for each configuration. Do i need to use the same approach for ASP.NET Core application as well?

2. How do i set aspnetcore_environment in .pubxml file?

3. If the approach specified in Question 1 is obsolete, then what's the alternate approach? ( I use Jenkins for CI)

Update 1

I understand that I have to set ASPNETCORE_ENVIRONMENT however I am not able to understand where do we set this? During development I can set this in profile in launchSettings.json, however question was how do we set this when publishing to staging or production? do we set environment variable on the target server itself?

Update 2
I found article here that explains different ways of setting environment variable. This partially answered my question. However when I publish the application, the publish process does not honor the environment variable while publishing appsettings.{env.EnvironmentName}.json
I have created separate post for that question

Answer 1

You could pass in the desired ASPNETCORE_ENVIRONMENT into the dotnet publish command as an argument using:

/p:EnvironmentName=Staging

e.g. dotnet publish /p:Configuration=Release /p:EnvironmentName=Staging

This will generate out the web.config with the correct environment specified for your project:

    <environmentVariables>
      <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Staging" />
    </environmentVariables>