Add a configurable base path

[ckocyigit]

Hello,

it would be nice to be able to run the whole application under a base path.

E.g.: localhost:5000/app

I've tried:

var appPath = Environment.GetEnvironmentVariable("BASE_PATH");
if (!string.IsNullOrEmpty(appPath))
{
    app.Use(async (context, next) =>
    {
        context.Request.PathBase = new PathString(appPath);
        await next();
    });
}

And

var basePath = Environment.GetEnvironmentVariable("BASE_PATH");
if (!string.IsNullOrEmpty(basePath))
{
    app.UsePathBase(basePath);
}

Within Program.cs.
But both attemps unfortuntely were unsuccessful

UsePathBase however worked for the login-screen and started trying to redirect to non-UsePathBase patterns afterwards.