Kestrel improvements for 2.0

[tdykstra]

• Remove text that warns against using Kestrel in edge deployments; no positive "approved for edge deployment" language yet
• New Kestrel limits and configuration in 2.0 - Add IWebHostBuilder.UseKestrel(options) overload to configure Kestrel aspnet/KestrelHttpServer#720 https://blogs.msdn.microsoft.com/webdev/2017/06/28/introducing-asp-net-core-2-0-preview-2/
  • RequestBodySizeLimit has a default value that will break some apps. Recommended workaround is to use attribute to change limit on a per action basis -- RequestSizeLimitAttribute
• IISIntegration is automatically called when running with IIS
  • When using the metapackage (IISIntegration is in the smaller package MS.AspNet.Core package, so this applies even if targeting .NET Framework)
  • When installing packages individually, however no compile error if you use individual packages and don't include IISIntegration and don't call IISIntegration explicitly. (update ANCM doc)
  • CreateDefaultBuilder calls it.
  • ANCM sets a light-up environment variable: even if you didn't call IISIntegration in your code, run this module and add it.
• Don't use UseURLs anymore
  • UseIISIntegration overrides new listen config API which in turn overrides UseURLs API
  • If you do use UseURLs, you can't include HTTPS URLs (we throw an exception)
  • UseHttps moved from KestrelServerOptions to ListenOptions
  • UseUrls is useful if you're not using SSL and you want to be able to switch servers (that and for backward compatibility is why we kept it)
• New listen config API
  • New Kestrel endpoint configuration API aspnet/Announcements#212
  • [Announcement] New Kestrel endpoint configuration API aspnet/KestrelHttpServer#1305
  • Create a direct way to configure endpoints on Kestrel aspnet/KestrelHttpServer#996
  • Kestrel configuration changes aspnet/Announcements#168
  • Kestrel has settings per prefix, HttpSys doesn't
  • No need to document ListenHandle -- niche use case
  • ListenUnixSocket is for enhancing performance with nginx. it existed before in UseUrls (you could specify a unix file path for the location of the socket), now you can do it in a type-safe way-- mention in the nginx tutorial - "Publish to a Linux Production Environment" should suggest using UNIX sockets #3068
• corresponding changes in fundamentals/hosting.md
• With CreateDefaultBuilder which already calls UseKestrel, to configure options: Services.Configure(KestrelOptions) up until the server starts
• "If you specify port number 0, Kestrel dynamically binds to an available port. Binding to port 0 is allowed for any host name or IP except for localhost name."

[tdykstra]

New settings are detailed here: https://blogs.msdn.microsoft.com/webdev/2017/06/28/introducing-asp-net-core-2-0-preview-2/