Using the File provider in DSC - Ensure Destination only contains files from Source

I am new to DSC. Spent the best part of Sunday afternoon looking at the resources and trying to figure out how to solve this. So, I sincerely thank you for that. It was fun looking up on DSC.

I think, this could work:

Configuration TestRun{  Param     (      $ComputerName = 'Localhost'    )    Node $ComputerName    {        Script RemoveModules {             GetScript = {#needs to return hashtable.}            SetScript = {                 $ump = "$HOME" + "\Documents\WindowsPowerShell\Modules\"                Remove-Item -Path $ump -Recurse -Force            }            TestScript = {                 $ump = "$HOME" + "\Documents\WindowsPowerShell\Modules\"                $mp = "C:\git\Modules"                if((Compare-Object $(gci $mp) $(gci $ump))){                    $false #at least one difference exists, SetScript will be called.                }else{                    $true #nothing is different                }            }        }        File LoadModules        {            Ensure = 'Present'            Type = 'Directory'            Force = $true            Recurse = $true            SourcePath = "C:\git\Modules"            DestinationPath = 'C:\users\Jason\Documents\WindowsPowerShell\Modules'            DependsOn = "[Script]RemoveModules"            Checksum = "SHA-256"            MatchSource = $true        }    }}

References:

• DSC Script Resource
• DSC File Resource
• PowerShellMagazine - Tag DSC

You can first copy the files and then delete the unnecessary ones:

Configuration DirectoryCopy{    param    (        [Parameter(Mandatory)]        [ValidateNotNullOrEmpty()]        [String] $SourcePath,        [Parameter(Mandatory)]        [ValidateNotNullOrEmpty()]        [String] $DestinationPath    )    File CopyFiles    {        SourcePath      = $SourcePath        DestinationPath = $DestinationPath        Type            = 'Directory'        Recurse         = $true        Checksum        = 'SHA-256'  # Overwrite modified files        Force           = $true    }    Script DeleteAdditionalDestinationFiles    {        TestScript =        {            $currentFiles = Get-ChildItem $using:DestinationPath -Recurse            $desiredFiles = Get-ChildItem $using:SourcePath -Recurse            $hasAdditionalFiles = [bool](Compare-Object -ReferenceObject $currentFiles -DifferenceObject $desiredFiles)            return !$hasAdditionalFiles        }        SetScript =        {            $currentFiles = Get-ChildItem $using:DestinationPath -Recurse            $desiredFiles = Get-ChildItem $using:SourcePath -Recurse            $additionalFiles = Compare-Object -ReferenceObject $currentFiles -DifferenceObject $desiredFiles | Select-Object -ExpandProperty InputObject            # First remove the directories and all its descendants.            $additionalFiles | Where-Object { ($_.Attributes -band [IO.FileAttributes]::Directory) -eq [IO.FileAttributes]::Directory } | Remove-Item -Recurse -Verbose            # Remove the remaining files that were not in any already removed directory.            $additionalFiles | Where-Object { Test-Path -Path $_.FullName } | Remove-Item -Verbose        }        GetScript = {            $currentFiles = Get-ChildItem $using:DestinationPath -Recurse            return @{                Result     = $currentFiles                TestScript = $TestScript                SetScript  = $SetScript                GetScript  = $GetScript            }        }        DependsOn = '[File]CopyFiles'    }}

In this way, if there are any directory tree change, it will not be necessary to delete all files before copying the desired ones. Only files that must be added, modified or removed will be affected.