For a few months now, I’ve been contemplating potential uses for a custom Sitecore.IO.FileWatcher — this lives in Sitecore.Kernel.dll, and defines abstract methods to handle changes to files on the file system within your Sitecore web application — and finally came up with something: how about a FileWatcher that restarts the Sitecore server when a certain file is uploaded to a specific directory?

You might be thinking “why would I ever want use such a thing?” Well, suppose you need to restart the Sitecore server on one of your Content Delivery Servers immediately, but you do not have direct access to it, and the person who does has left for the week. What do you do?

The following FileWatcher might be one option for the scenario above (another option might be to make frantic phone calls to get the server restarted):

using System;

using Sitecore.Diagnostics;
using Sitecore.Install;
using Sitecore.IO;

namespace Sitecore.Sandbox.IO
{
    public class RestartServerWatcher : FileWatcher
    {
        public RestartServerWatcher()
            : base("watchers/restartServer")
        {
        }

        protected override void Created(string fullPath)
        {
            try
            {
                Log.Info(string.Format("Restart server file detected: {0}. Restarting the server.", fullPath), this);
                FileUtil.Delete(fullPath);
                Installer.RestartServer();
            }
            catch (Exception exception)
            {
                Log.Error("Error in RestartServerWatcher", exception, typeof(RestartServerWatcher));
            }
        }
        
        protected override void Deleted(string filePath)
        {
            return;
        }

        protected override void Renamed(string filePath, string oldFilePath)
        {
            return;
        }
    }
}

All of the magic occurs in the Created() method above — we do not care if the file is renamed or deleted. If the file is detected, the code in the Created() method logs information to the Sitecore log, deletes the file, and then initiates a Sitecore server restart.

I created the following patch configuration file for the RestartServerWatcher class above:

<?xml version="1.0" encoding="utf-8" ?>
<configuration xmlns:patch="http://www.sitecore.net/xmlconfig/">
  <sitecore>
    <watchers>
      <restartServer>
        <folder>/restart</folder>
        <filter>restart-server.txt</filter>
      </restartServer>
    </watchers>
  </sitecore>
</configuration>

Since FileWatchers are HttpModules, I had to register the RestartServerWatcher in the <system.webServer> section of my Web.config (this configuration element lives outside of the <sitecore> configuration element, and cannot be mapped via a Sitecore patch configuration file):

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<!-- Lots of stuff up here -->
<system.webServer>
	<!-- Some stuff here -->
	<add type="Sitecore.Sandbox.IO.RestartServerWatcher, Sitecore.Sandbox" name="SitecoreRestartServerWatcher"/>
</system.webServer>
<!-- More stuff down here -->
</configuration>

For testing, I uploaded my target file into the target location via the Sitecore File Explorer to trigger a Sitecore server restart:

I then opened up my Sitecore log, and saw the following entries:

If you have any thoughts on this, or have other ideas for custom FileWatchers, please share in a comment.