Multiple ASP.NET Core Web API instances runs only once

[adryone]

I have an ASP.NET Core 8.0 Web API hosted on two IIS applications (app-1 and app-2) under the Default Web Site on a Windows 11 OS.

Both IIS applications point to the same physical path (inetpub\wwwroot\myapp) and each application has its own dedicated application pool (app1 and app2). The application pools have unique identities (app1svc and app2svc), both of which are members of the Administrators group.

In the Web API, I have an AppEvents class implementing IHostedService, with StartAsync and StopAsync methods to handle application start and stop events. In the Program.cs, I register it using builder.Services.AddHostedService<AppEvents>().

When accessing http://localhost/app-1, the StartAsync method is triggered as expected. However, when accessing http://localhost/app-2, the StartAsync method does not execute. The WebApi application behind http://localhost/app-1 or http://localhost/app-2 starts only once, the first one that is requested.

I've tried changing the AspNetHostingModel from InProcess to OutOfProcess, but the behavior remains the same.

Is there a way to deploy multiple instances of the same web app, each running separately but pointing to the same physical directory, so that each instance correctly triggers its own StartAsync?``

[davidfowl]

@BrennanConroy ?

[adryone]

Hi David,

after several hours spent on the questiuon, I've found the "real" problerm.
For monitoring I use NLog; the problem is that in the second "instance" of WebApi NLog does not write (there's a breaking change on NLog where the default of KeepFileOpen is changed from false to true).

Thanks