Stopping a Web Site to Remove Locked Log Files During a WiX Uninstall

So for my employer, Skiviez, I’ve created a WiX installer for the Web site. It’s pretty sweet: just double-click the MSI, and insto presto, you have a Web site installed, with the directories created, permissions set correctly, and IIS configured correctly.

The Web site uses log4net for logging, and it uses the RollingFileAppender to log information in a Logs directory for the Web site. In WiX, this behavior is specified in the usual way:

  <Directory Id="DirectoryLogs" Name="Logs">
	<Component Id="ComponentCreateFolderLogs" Guid="{DAB6113C-83BA-422d-9D77-43F112BE7EF7}">
	  <CreateFolder>
		<Permission
		  GenericRead="yes"
		  GenericWrite="no"
		  GenericExecute="no"
		  Read="yes"
		  User="Authenticated Users" />
		<Permission
		  GenericAll="yes"
		  User="NT AUTHORITY\NETWORK SERVICE" />
	  </CreateFolder>
	  <RemoveFile
		Id="RemoveFileLogsAll"
		Name="*.*"
		On="uninstall" />
	</Component>
	<Component Id="ComponentConfigWebLogs" Guid="{82B14CA7-96B1-4c92-8E6E-846C8E17ED02}">
	  <File
		Id="FileConfigWebLogs"
		Name="Web.config"
		Source="$(var.Skiviez.Armadillo.UI.Web.ProjectDir)Logs\"
		KeyPath="yes" />
	</Component>
  </Directory>

There is nothing particularly exotic going on here. I tell Windows Installer to create the Logs folder, set some permissions on it so that NETWORK SERVICE (which the Web site runs as) can read and write to the folder and so that I (as an Authenticated User can easily read it), copy in a Web.config that locks down the folder from being served by IIS, and tell Windows Installer to remove all of the log files during uninstall. I’ve written this a bazillion times before and it works fine for most programs.

But when I tried to uninstall while the Web site was still running, the uninstallation would fail because the log file was still locked by the Web site. This is because WiX’s custom action that finagles with IIS runs after the standard RemoveFiles action in Windows Installer. Some poor soul seemed to be having my exact same problem, but no answers there.

Since this is the only Web site running on the server, an easy solution is to use another built-in WiX custom action to stop IIS during uninstallation and then start it back up again afterward. This has the advantage of spinning down the ASP.NET worker process so that the lock on the file is released, RemoveFiles completes successfully, the WiX IIS custom action removes the Web site, and finally IIS is gracefully started back up again.

I’m not sure why it wasn’t obvious to me; took me a good 45 minutes to figure this out.

Just drop this in the same Component that your Web site is defined in:

<ServiceControl
  Id="ServiceControlWebSiteMain"
  Name="W3SVC"
  Start="both"
  Stop="both"
  Wait="yes" />

(Side note: Windows Installer’s architecture is completely insane. I reckon I’ll save that rant for another post. Perhaps the most amusing bit is that when uninstallation fails for some reason, such as the situation described in this post, Windows Installer will happily re-install everything back to the way it was! Ha!)

Happy uninstalling!