Find Windows containers orphan layers

Find-OrphanDockerLayers.ps1

param (
    [switch]$RenameOrphanLayers
)

If ($RenameOrphanLayers) {
	Write-Warning "$($env:COMPUTERNAME) -RenameOrphanLayers option enabled, will rename all orphan layers"
}

# Get known layers on Docker images
[array]$ImageDetails += docker images -q | ForEach { docker inspect $_ | ConvertFrom-Json }
ForEach ($Image in $ImageDetails) {
	$ImageLayer = $Image.GraphDriver.Data.dir
	
	[array]$ImageLayers += $ImageLayer
	$LayerChain = Get-Content "$ImageLayer\layerchain.json"
	If ($LayerChainFileContent -ne "null") {
		[array]$ImageParentLayers += $LayerChain | ConvertFrom-Json
	}
}

# Get known layes on Docker containers
[array]$ContainerDetails = docker ps -a -q | ForEach { docker inspect $_ | ConvertFrom-Json}
ForEach ($Container in $ContainerDetails) {
	[array]$ContainerLayers += $Container.GraphDriver.Data.dir
}

# Get layers on disk
$LayersOnDisk = (Get-ChildItem -Path C:\ProgramData\Docker\windowsfilter -Directory).FullName
$ImageLayers += $ImageParentLayers
$UniqueImageLayers = $ImageLayers | Select-Object -Unique
[array]$KnownLayers = $UniqueImageLayers
$KnownLayers += $ContainerLayers

# Find orphan layers
$OrphanLayersTotal = 0
ForEach ($Layer in $LayersOnDisk) {
	If ($KnownLayers -notcontains $Layer) {
		[array]$OrphanLayer += $Layer
		$LayerSize = (Get-ChildItem -Path $Layer -Recurse -ErrorAction:SilentlyContinue | Measure-Object -Property Length -Sum -ErrorAction Stop).Sum
		$OrphanLayersTotal += $LayerSize
		Write-Warning "$($env:COMPUTERNAME) - Found orphan layer: $($Layer -Replace '\r\n','') with size: $(($LayerSize -Replace '\r\n','') / 1MB) MB"
		
		If (($RenameOrphanLayers) -and ($Layer -notlike "*-removing")) {
			$LayerNewPath = $Layer + "-removing"
			Rename-Item -Path $Layer -NewName $LayerNewPath
		}
	}
}

Write-Host "$($env:COMPUTERNAME) - Layers on disk: $($LayersOnDisk.count)"
Write-Host "$($env:COMPUTERNAME) - Image layers: $($UniqueImageLayers.count)"
Write-Host "$($env:COMPUTERNAME) - Container layers: $($ContainerLayers.count)"
$OrphanLayersTotalMB = $OrphanLayersTotal / 1MB
Write-Warning "$($env:COMPUTERNAME) - Found $($OrphanLayer.count) orphan layers with total size $OrphanLayersTotalMB MB"

@bctails I do not have rights to open those issues. Technically this bug have been fixed already long time ago but unfortunately it looks that Mirantis deal messed up Docker release process and they have not been able release new version. I also proposed that this would be released as part of hotfix version but it was denied (you can find discussion from docker/engine#268 )

Anyway, you can use my custom build which contains those fixes and which we have been running even on production environment > 8 months now without issues https://github.com/olljanat/moby/releases/tag/19.03.5-olljanat2