Publishing and Running ASP.NET Core Applications with IIS

I have searched about publishing and running asp.net core application in IIS and during searched I found Rick strahl’s web log “Publishing and Running ASP.NET Core Applicationsin IIS” which help me a lot to understand how could we use IIS with ASP.NET Core applications. Below are the points taken from that blog.

The most important thing to understand about hosting ASP.NET Core is that it runs as a standalone, out of process Console application. It's not hosted inside of IIS and it doesn't need IIS to run. ASP.NET Core applications have their own self-hosted Web server and process requests internally using this self-hosted server instance.

You can however run IIS as a front end proxy (reverse proxy) for ASP.NET Core applications, because Kestrel is a raw Web server that doesn't support all features a full server like IIS supports. This is actually a recommended practice on Windows in order to provide port 80/443 forwarding which kestrel doesn't support directly. For Windows IIS (or another reverse proxy) will continue to be an important part of the server even with ASP.NET Core applications.

Here my main focus is, whether I should use IIS during development of ASP.Net Core Application (to run and debug) or not?

There should be very few reasons for you to run IIS during development. Yes, in the past there were very good reasons to run full IIS because there were always a number of things that behaved very differently in full IIS compared to IIS Express. However, with ASP.NET Core there's little to no reason to be running full IIS during development. Why? Because ASP.NET Core applications aren't actually running inside of IIS. Whether you running called from IIS, IIS Express or whether you do dotnet run directly from the command line - you are running the exact same code and in most cases the exact same execution environment. Running inside of IIS really doesn't buy you anything anymore that you can't easily simulate with a command line environment.

The only reason you might need to run under IIS if there is something that IIS provides in terms of HTTP services that is really separate from the ASP.NET Core processing. But even then it's likely that those features won't be something you need to debug in the context of your application.

The reason that you can't ‘just run IIS’ from your development environment is that an ASP.NET Core application has to be published before it can be executed. The development folder doesn't hold all the files necessary to run your application. When you 'debug' or ‘run’ your application the application is first published to a separate location and run from there. For this reason you don't see IIS as an option in Visual Studio for example.

If you absolutely have to run with IIS, you can publish the application to a local folder first, then configure an IIS virtual directory or site and use that to run your site.