Environment variable set but HostingEnvironment.EnvironmentName not updated

user_3206983 0
Viewed 4245

Am running .net core 2.2 and hosting asp.net core within a windows service.
eg. see this https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/windows-service?view=aspnetcore-2.2&tabs=visual-studio

I set the environment variable ASPNETCORE_ENVIRONMENT to "Dev"

Just to confirm, within my launchsettings.json

  "environmentVariables": {
    "ASPNETCORE_ENVIRONMENT ": "Dev"
  }

enter image description here

When starting up the value of HostingEnvironment.EnvironmentName is not updated and still has "Production" which is default. Why is it not "Dev"?

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)                
        .ConfigureLogging((hostingContext, logging) =>
        {
            logging.AddEventLog();
        })
        .ConfigureAppConfiguration((context, config) =>
        {

            // Configure the app here.
            var env = context.HostingEnvironment;
            config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                              .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);

        })
        .UseStartup<Startup>();

}

asp.net-core .net-core
1 Answers

I spent quite a while trying to work out the best thing for me to do in this situation.

I ended up taking the code from Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder and adding the .UseEnvironment extension on the builder.

            builder.UseEnvironment(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Development");

I default to Development rather than the generally preferred Production, but that was personal preference.

It is limited and if you want to be clever and check for commandline arguments etc and so forth, feel free. It's a place to start.

public static IHostBuilder CreateDefaultBuilder(string[] args)
{
    var builder = new HostBuilder();

    // This line has been added to read the environment variable.
    builder.UseEnvironment(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Development");

    builder.UseContentRoot(Directory.GetCurrentDirectory());
    builder.ConfigureHostConfiguration(config =>
    {
        config.AddEnvironmentVariables(prefix: "DOTNET_");
        if (args != null)
        {
            config.AddCommandLine(args);
        }
    });

    builder.ConfigureAppConfiguration((hostingContext, config) =>
    {
        var env = hostingContext.HostingEnvironment;

        config.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);

        if (env.IsDevelopment() && !string.IsNullOrEmpty(env.ApplicationName))
        {
            var appAssembly = Assembly.Load(new AssemblyName(env.ApplicationName));
            if (appAssembly != null)
            {
                config.AddUserSecrets(appAssembly, optional: true);
            }
        }

        config.AddEnvironmentVariables();

        if (args != null)
        {
            config.AddCommandLine(args);
        }
    })
    .ConfigureLogging((hostingContext, logging) =>
    {
        var isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);

        // IMPORTANT: This needs to be added *before* configuration is loaded, this lets
        // the defaults be overridden by the configuration.
        if (isWindows)
        {
            // Default the EventLogLoggerProvider to warning or above
            logging.AddFilter<EventLogLoggerProvider>(level => level >= Microsoft.Extensions.Logging.LogLevel.Warning);
        }

        logging.AddConfiguration(hostingContext.Configuration.GetSection("Logging"));
        logging.AddConsole();
        logging.AddDebug();
        logging.AddEventSourceLogger();

        if (isWindows)
        {
            // Add the EventLogLoggerProvider on windows machines
            logging.AddEventLog();
        }
    })
    .UseDefaultServiceProvider((context, options) =>
    {
        var isDevelopment = context.HostingEnvironment.IsDevelopment();
        options.ValidateScopes = isDevelopment;
        options.ValidateOnBuild = isDevelopment;
    });

    return builder;
}
user_20951100
Related