Generic Host Builder and HostingEnvironment.IsDevelopment

[Eilon]

From @dazinator on July 5, 2018 17:7

I am using the new generic host in 2.1.0 as documented here: https://docs.microsoft.com/en-us/aspnet/core/fundamentals/host/generic-host?view=aspnetcore-2.1

When the hosting environment is development, I'd like to add user secrets:

  .ConfigureAppConfiguration((hostContext, configApp) =>
                   {
                       configApp.AddJsonFile("appsettings.json", optional: true);                   
                       if (hostContext.HostingEnvironment.IsDevelopment())
                       {
                           configApp.AddUserSecrets<Program>();
                       }
                       configApp.AddEnvironmentVariables(prefix: "FOO_");
                       configApp.AddCommandLine(args);
                   })

However IsDevelopment always returns false.
Yet I have set the ASPNETCORE_ENVIRONMENT enironment variable. Here is my launch settings:

{
  "profiles": {
    "Foo": {
      "commandName": "Project",
      "environmentVariables": {
        "ASPNETCORE_ENVIRONMENT": "Development"
      }
    }
  }
}

It would make sense if ASPNETCORE_ENVIRONMENT was no longer used to control this for a generic host as we are not in asp.net core land - but in that case is there now a different environment variable name for this, or do we set the Environment name ourselves in code?

Copied from original issue: #3298

[Eilon]

From @dazinator on July 5, 2018 17:11

This seems like a sensible workaround, but it would be better if this behaviour was automatic to be consistent with asp.net core scenarios?

.ConfigureAppConfiguration((hostContext, configApp) =>
                   {
                       hostContext.HostingEnvironment.EnvironmentName = System.Environment.GetEnvironmentVariable("NETCORE_ENVIRONMENT");

[muratg]

Tentatively putting this in 3.0.

pinging @davidfowl @Tratcher for their thoughts.

[Tratcher]

ASPNETCORE_ENVIRONMENT isn't expected to work, as you say, this isn't ASP.NET Core land.

GenericHost does not register any configuration providers by default, not even environment variables.
https://docs.microsoft.com/en-us/aspnet/core/fundamentals/host/generic-host?view=aspnetcore-2.1#host-configuration
https://github.com/aspnet/Hosting/blob/c9a4ee8b719ffb01eb44705d68efd158eb80c221/src/Microsoft.Extensions.Hosting/HostBuilder.cs#L121
https://github.com/aspnet/Hosting/blob/f9d145887773e0c650e66165e0c61886153bcc0b/src/Microsoft.Extensions.Hosting/HostBuilder.cs#L134

[dazinator]

@Tratcher
If its not expected to work the same, having the IsDevelopment() API exposed still is a little misleading. Especially for those with asp.net core experience, they will see this API (like I did) and expect to be able to use it in the same way.

                       if (hostContext.HostingEnvironment.IsDevelopment())
                       {
                          
                       }

If this API was not present, I wouldn't have raised an issue. On Dev machines, this always returned true by default until now so that might catch people out.

[davidfowl]

To be practical here we might just have to recognize ASPNETCORE_ENVIRONMENT in the generic host.

[Tratcher]

I meant that no environment variables are recognized by default, that's opt-in. IsDevelopment doesn't check ASPNETCORE_ENVIRONMENT, it checks config["environment"], and the environment variable config provider deals with prefixes like ASPNETCORE_. That's all under your control setting up the HostBuilder.

We'll see what defaults we decide to bring back, or if we mirror the CreateDefaultBuilder pattern to get something bootstrapped for you.

[dazinator]

@Tratcher got ya. Ok thanks.

[rbugginsvia]

I've just been having issues with this and i noticed that the environment is not set from ConfigureAppConfiguration but from ConfigureHostConfiguration on the HostBuilder

[pksorensen]

From a user that dont already read the docs i did use some time here to find out that the enviromentname is defaulted to production ( also causing some pain to find out it altered production environment).

I think it would have been a good idea to add environment variables as default to hostconfiguration :)
and use a fallback on aspnetcore_environment.

I just added to my solution

              .ConfigureHostConfiguration((configurationBuilder)=>{
                  configurationBuilder
                    .AddInMemoryCollection(new[] { new KeyValuePair<string, string>(HostDefaults.EnvironmentKey, System.Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT")) })
                    .AddEnvironmentVariables();
              })

[muratg]

@davidfowl @Tratcher Are we doing something here for 3.0?

[Tratcher]

Yes this needs design.