The AspNet Core 2.1-preview1 is out and it brings a ton of interesting improvements. One of which is that now you are able to host your AspNet app inside the IIS process. This, according to AspNet team will increase the request throughput by around 4.4 times. I did it for my app and faced a few issues that I though is worth describing here along with a process that I followed. “Improvements to IIS hosting” blog post from AspNet team lists steps needed to change your app hosting model. To my surprise there is only three of them:
inprocessin your project file.
Installation of Windows Server Hosting bundle is pretty straight forward and quite fast, I didn’t encounter any issues with it. One note here is that it is recommended to do
iisreset after this step.
UPD: The PR with a fix for the script was merged, so I updated the URL to take the version of the script from official repository.
If the script executed successfully there should be an
AspNet Core Module in the list of modules in IIS.
Since this is a
Native module the app pool can stay with “No managed code” option for CLR version.
Now lets get to what needs to change in the application code itself. First thing is to set
inprocess in the project file. This is done by adding a
PropertyGroup to the project file:
This will not change the behavior of the app when running locally, but it will instruct MSBuild to add
hostingModel="inprocess" property to the
ANCM entry in the
web.config. The resulting
web.config should look like this:
If you’ve created your application from 2.0 template, as I did, you will have
UseContentRoot(Directory.GetCurrentDirectory()) entry in
Program.cs. This should be removed as it will cause the application to fail. The reason is that when hosting inside
w3wp GetCurrentDirectory will return
C:\windows\system32\inetsrv while the app is in the
C:\inetpub\wwwroot\InProcTest so ANCM will not find your app and will complain with the status code of 500. The 2.1 app is smart enough to figure out its own location anyway. :)
UPD: Before, I mentioned that
UseIISIntegration() can be removed from the
Program.cs as it was not needed, this is not entirely correct. @jkotalik pointed out that
UseIISIntegration() is still necessary for
InProcess hosting as it will register IIS specific services and options and will set the content root path correctly. The good news it that WebHost.CreateDefaultBuilder will add
UseIISIntegration() by default, so no need to add it in
After this changes, run the app and it should load without issues.
Side note, with this model, you can run only one app per IIS process. This is a decision that AspNet team made and also currently a limitation from .Net Core as it does not have support for multiple AppDomains.
No, one app per process— Damian Edwards (@DamianEdwards) March 1, 2018
Kinda, but even if it did, I'm not sure we'd do it. The gymnastics System.Web pulls to do that aren't really seen as idiomatic guidance anymore, i.e. each app should be in its own process.— Damian Edwards (@DamianEdwards) March 1, 2018