ASP.NET Core – Environment Variable

· ASP.NET Core uses an environment variable called ASPNETCORE_ENVIRONMENT to indicate the runtime environment.

· The value of this variable can be anything as per your need but typically it can be Development, Staging, or Production.

· The value is case insensitive in Windows and Mac OS but it is case sensitive on Linux.

· In Visual Studio, we can set ASPNETCORE_ENVIRONMENT in the debug tab of project properties.

· Open project properties by right clicking on the project in the solution explorer and select Properties.

· This will open properties page. Click on Debug tab and you will see Environment Variables as shown below.

· You may change the value as per your need. This value will be saved in the launchSettings.json file as shown below.

· You may also change the environment variable directly in launchSettings.json.

Access Environment Variable at Runtime

· We can get the value of an environment variable in our code to execute some additional code based on its value. 

· The IHostingEnvironment service includes EnvironmentName property which contains the value of ASPNETCORE_ENVIRONMENT variable.

· ASP.NET Core also includes extension methods to check the environment such as IsDevelopment(), IsStating(), IsEnvironment() and IsProduction().

· The IHostingEnvironment service is provided by ASP.NET hosting layer and can be used anywhere in your application via Dependency Injection.

· Given below example shows how we can check the environment variable in the Configure method of Startup class.

public void Configure(IApplicationBuilder app, IHostingEnvironment env)

{

    if (env.IsEnvironment(“Development”))

    {

        // code to be executed in development environment

    }

    if (env.IsDevelopment())

    {

        // code to be executed in development environment

    }

    if (env.IsStaging())

    {

        // code to be executed in staging environment

    }

    if (env.IsProduction())

    {

        // code to be executed in production environment

    }

}