Mary Lark, Full Stack Engineer

Background:

Watcher.ps1 is intended to run on a virtual machine. In the paradigm we were working with, virtual machines are created by copying from a pristine archive copy of a virtual machine. An archive is a virtual machine, operating system and software installed, group policy, registry and user settings set properly. The virtual machine is then shut-down. From this point forward, the virtual machine is referred to as an archive, and is typically never started again. They are simply copied and the copy is used. This way we can guarantee the integrity of the VM assigned to the user.

Once the archive has been created and shut down, the new vm is then copied and started. When the VM is running the user’s files are mounted via a network mount and the machine is ready for the user to log on.

Upon logoff, the user files are dismounted, and the virtual machine is then destroyed.

About the powershell script:

In some cases we can point software to look to the network mount for its files, rather than the C:\ drive, however in some cases the software cannot be redirected. Such is the case with Dreamweaver. Dreamweaver expects the website files to reside in c:\inetpub\wwwroot. But because the c:\ drive is destroyed when the user logs out, we had to devise a mechanism such that the files from the user’s persistent storage were automatically copied to the c:\inetpub\wwwroot directory at login — and when the files were updated, these updates would be mirrored in the user’s persistent storage.

In this script, the watcher object is a file system object provided by powershell. The watcher object has event-driven methods that automatically respond to events that can occur on a file system object. The watcher object has the ability to determine which files are changed, deleted, or added.

Initially we define toPath as the path to the persistent storage. We copy all files from toPath down to c:\inetpub\wwwroot as the user logs on. Once copied, we begin watching the file system and based upon the event that occurs (creation, deletion, or change) watcher will execute accordingly.

At anytime the user logs off we know that the files on the persistent storage mirror exactly the files in wwwroot directory. When the virtual machine shuts down,the persistent storage (network mounted drive) is then detached and preserved, and finally the virtual machine is destroyed.

When the student logs back in, a new clean virtual machine is cloned from the pristine archive copy, the persistent storage is mounted on the virtual machine via a network mount, and the files are then copied down into wwwroot for use by Dreamweaver. Rinse and repeat.

Watcher: The event-driven code:

$labID=$args[0]
$watcher = New-Object System.IO.FileSystemWatcher
$watcher.Path = 'c:\inetpub\wwwroot'
$watcher.IncludeSubdirectories = $true
$watcher.NotifyFilter = 
   [System.IO.NotifyFilters]::LastWrite 
   -bor [System.IO.NotifyFilters]::FileName 
   -bor [System.IO.NotifyFilters]::DirectoryName

$toPath = "c:\users\student\links\WebServerManagedFolder\"
$pso = new-object psobject -property @{toPath = $toPath}

Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
	 -Append -InputObject "     Deleting contents of wwwroot"
get-childitem c:\inetpub\wwwroot\* 
	 -recurse | remove-item -force -recurse
Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
	 -Append -InputObject 
	 "    Copying contents of $toPath to wwwroot"
Copy-Item $toPath* c:\inetpub\wwwroot\ -recurse


Register-ObjectEvent $watcher Created -SourceIdentifier 
	 FileCreated -MessageData $pso -Action {
	$name = $Event.SourceEventArgs.Name
	$fullPath = $Event.MessageData.toPath + $name
	$fullName = "c:\inetpub\" + $name
	$changeType = $Event.SourceEventArgs.ChangeType
	$timeStamp = $Event.TimeGenerated
	$toPath = $Event.MessageData.toPath
	
	Write-Host ""
	Write-Host ""
	Write-Host "FILE CREATED" -fore green
	Write-Host "============" -fore green
	Write-Host "  FileName:      $name" -fore green
	Write-Host "  Copy from:     $fullName" -fore green
	Write-Host "  Copy to:       $fullPath" -fore green
	Write-Host "  Change type:   $changeType" -fore green
	Write-Host "  Time:          $timeStamp" -fore green
	Write-Host "  ToPath:        $toPath" -fore green

	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject "The file '$name' was $changeType 
		 at $timeStamp"
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject 
		 "     Deleting contents of $toPath"
	get-childitem $toPath* -recurse | remove-item -force -recurse
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject 
		 "     Copying contents of c:\inetpub\wwwroot to $toPath"
	Copy-Item c:\inetpub\wwwroot\* $toPath -recurse
}

Register-ObjectEvent $watcher Deleted -SourceIdentifier 
	FileDeleted -MessageData $pso -Action {
	$name = $Event.SourceEventArgs.Name
	$fullPath = $Event.MessageData.toPath + $name
	$fullName = "c:\inetpub\" + $name
	$changeType = $Event.SourceEventArgs.ChangeType
	$timeStamp = $Event.TimeGenerated
	$toPath = $Event.MessageData.toPath
	
	Write-Host ""
	Write-Host ""
	Write-Host "FILE DELETED"  -fore red
	Write-Host "============" -fore red
	Write-Host "  FileName:              $name" -fore red
	Write-Host "  Deleted from:          $fullName" -fore red
	Write-Host "  Deleting in target:    $fullPath" -fore red
	Write-Host "  Change type:           $changeType" -fore red
	Write-Host "  Time:                  $timeStamp" -fore red
	Write-Host "  ToPath:                $toPath" -fore red

	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject 
		 "The file '$name' was $changeType at $timeStamp"
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject "     
		 Deleting contents of $toPath"
	get-childitem $toPath* -recurse | 
		 remove-item -force -recurse
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject 
		 "     Copying contents of c:\inetpub\wwwroot to $toPath"
	Copy-Item c:\inetpub\wwwroot\* $toPath -recurse
}

Register-ObjectEvent $watcher Changed -SourceIdentifier 
	 FileChanged -MessageData $pso -Action {
	$name = $Event.SourceEventArgs.Name
	$fullName = "c:\inetpub\" + $name
	$fullPath = $Event.MessageData.toPath + $name
	$changeType = $Event.SourceEventArgs.ChangeType
	$timeStamp = $Event.TimeGenerated
	$toPath = $Event.MessageData.toPath
	
	Write-Host ""  
	Write-Host ""  
	Write-Host "FILE Changed" -fore white
	Write-Host "============" -fore white
	Write-Host "  FileName:              $name" -fore white
	Write-Host "  Changed from:          $fullName" -fore white
	Write-Host "  Changing in target:    $fullPath" -fore white
	Write-Host "  Change type:           $changeType" -fore white
	Write-Host "  Time:                  $timeStamp" -fore white
	Write-Host "  ToPath:                $toPath" -fore white

	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject "The file '$name' was 
		 $changeType at $timeStamp"
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject "     Deleting contents of $toPath"
	get-childitem $toPath* -recurse | remove-item -force -recurse
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject 
		 "     Copying contents of c:\inetpub\wwwroot to $toPath"
	Copy-Item c:\inetpub\wwwroot\* $toPath -recurse
}

Register-ObjectEvent $watcher Renamed -SourceIdentifier FileRenamed 
	 -MessageData $pso -Action {
	$name = $Event.SourceEventArgs.Name
	$fullPath = $Event.MessageData.toPath + $name
	$changeType = $Event.SourceEventArgs.ChangeType
	$timeStamp = $Event.TimeGenerated
	$toPath = $Event.MessageData.toPath
	
	Write-Host ""
	Write-Host ""
	Write-Host "FILE Renamed " -fore yellow
	Write-Host "============" -fore yellow
	Write-Host "  FileName:              $name" -fore yellow
	Write-Host "  Copying from:          $fullName" -fore yellow
	Write-Host "  Copying to target:     $fullPath" -fore yellow
	Write-Host "  Deleting in target:    <Need code for this>" -fore yellow
	Write-Host "  Change type:           $changeType" -fore yellow
	Write-Host "  Time:                  $timeStamp" -fore yellow
	Write-Host "  ToPath:                $toPath" -fore yellow

	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject "The file '$name' was 
		 $changeType at $timeStamp"
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject "     Deleting contents of $toPath"
	get-childitem $toPath* -recurse | remove-item -force -recurse
	Out-File -FilePath c:\users\administrator\desktop\outlog.txt 
		 -Append -InputObject 
		 "     Copying contents of c:\inetpub\wwwroot to $toPath"
	Copy-Item c:\inetpub\wwwroot\* $toPath -recurse
}