iis - How can I update ASP.NET Core app over an existing/running site without stopping the web server?

Question

We have an ASP.NET Core site running on our test server that we would like to auto-deploy by XCopy to our IIS web server as we do our current apps, where I already have the site running. I've added a publish profile that packages the site to a "publish-local" directory within the solution. Whenever I try to copy over the existing site, all DLLs are being used by another process, presumably Kestrel, so I am forced to deploy to a sibling directory and re-map IIS to look at the sibling. How does one update a running ASP.NET Core site without having to manually intervene and stop either the Kestrel or IIS web servers?

Answer 1

When running with IIS you can drop a file called app_offline.htm (case sensitive) to your application folder. IIS will stop your application and will serve the contents of the app_offline.html file. Now you can copy your application. Once finished remove the app_offline.html and IIS will start your app. This is described in the docs and also in my post on running Asp.NET Core apps with IIS.