Convert OCI image to LXC format

convert-image.psm1

Function Convert-Image
{
	Param (
		[Parameter(Mandatory = $true)]
		[string]$Name,

		[Parameter(Mandatory = $true)]
		[string]$Tag,

		[Parameter(Mandatory = $false)]
		[string[]]$ServicesToDisable,

		[Parameter(Mandatory = $false)]
		[string[]]$ConfigurationFilesToCopy,

		[Parameter(Mandatory = $false)]
		[string]$ConfigurationFilesOwner,

		[Parameter(Mandatory = $false)]
		[string]$ConfigurationFilesMode
	)

	Read-Profile

	Write-Host "Run LXC image converter with options:"
	Show-Parameters -Parameters $PSBoundParameters

	$BaseLocation = "/data/image"
	$ContainerLocation = "/tmp/container"
	$ContainerName = "oci"
	$RootFileSystemLocation = "$ContainerLocation/$ContainerName/rootfs"
	$OciArchiveImage = "oci-archive:${Name}:${Tag}"
	$UncompressedTarName = "$Name-$Tag.tar"
	$CompressedTarName = "$UncompressedTarName.zst"

	Write-Host "Unpack to LXC format..."

	/usr/bin/skopeo copy "docker-archive:$BaseLocation/$UncompressedTarName" $OciArchiveImage

	/usr/bin/lxc-create `
		oci `
		--logpriority DEBUG `
		--lxcpath $ContainerLocation `
		--template oci -- --url "$OciArchiveImage"

	Write-Host "Update root file system..."

	Write-Host "`t * Mount mountpoints..."
	/usr/bin/mount --types proc /proc "$RootFileSystemLocation/proc/"
	/usr/bin/mount --types sysfs /sys "$RootFileSystemLocation/sys/"
	/usr/bin/mount --rbind --make-rslave /dev "$RootFileSystemLocation/dev/"

	Write-Host "`t * Install packages..."
	/usr/sbin/chroot $RootFileSystemLocation apt update
	/usr/sbin/chroot $RootFileSystemLocation apt install init -y
	/usr/sbin/chroot $RootFileSystemLocation apt install ifupdown2 -y

	Write-Host "`t * Install systemd services..."
	$ServiceFilenames = Get-ChildItem -Path /data/services -File -Name
	/usr/bin/cp /data/services/* $RootFileSystemLocation/lib/systemd/system/.

	foreach($ServiceFilename in $ServiceFilenames)
	{
		Write-Host "`t |-- $ServiceFilename"
		/usr/sbin/chroot $RootFileSystemLocation chmod 644 /lib/systemd/system/$ServiceFilename
		/usr/sbin/chroot $RootFileSystemLocation systemctl enable $ServiceFilename
	}

	Write-Host "`t * Register modules..."
	/usr/bin/mkdir $RootFileSystemLocation/scripts/
	/usr/bin/cp /scripts/* $RootFileSystemLocation/scripts/
	/usr/sbin/chroot $RootFileSystemLocation pwsh -Command Register-Modules

	Write-Host "`t * Post-install..."

	if($ServicesToDisable.Count -gt 0)
	{
		Write-Host "`t |-- Disable systemd services..."
	}

	foreach($ServiceNameToDisable in $ServicesToDisable)
	{
		Write-Host "`t |----- $ServiceNameToDisable"
		/usr/sbin/chroot $RootFileSystemLocation systemctl disable $ServiceNameToDisable
	}

	if($ConfigurationFilesToCopy.Count -gt 0)
	{
		Write-Host "`t |-- Copy configuration files..."
	}

	foreach($ConfigurationFileToCopy in $ConfigurationFilesToCopy)
	{
		Write-Host "`t |----- $ConfigurationFileToCopy"
		/usr/bin/cp $ConfigurationFileToCopy $RootFileSystemLocation/$ConfigurationFileToCopy
		Write-Host "`t |----- Owner '${ConfigurationFilesOwner}'"
		/usr/sbin/chroot `
			$RootFileSystemLocation `
			chown `
			${ConfigurationFilesOwner}:${ConfigurationFilesOwner} `
			$ConfigurationFileToCopy
		Write-Host "`t |----- Mode '${ConfigurationFilesMode}'"
		/usr/sbin/chroot `
			$RootFileSystemLocation `
			chmod `
			$ConfigurationFilesMode `
			$ConfigurationFileToCopy
	}

	Write-Host "`t * Unmount mountpoints..."
	/usr/bin/umount --recursive "$RootFileSystemLocation/dev/"
	/usr/bin/umount "$RootFileSystemLocation/proc/"
	/usr/bin/umount "$RootFileSystemLocation/sys/"

	/usr/sbin/chroot $RootFileSystemLocation rm --recursive /dev

	Write-Host "Pack '$Name' as compressed tarball..."

	cd "$ContainerLocation/$ContainerName"

	Write-Host "`t * Create rootfs tarball..."

	/usr/bin/tar `
		--numeric-owner `
		--create `
		--transform "s/rootfs/./" `
		--file /tmp/$UncompressedTarName `
		rootfs/

	Write-Host "`t * Compress tarball..."

	/usr/bin/zstd `
		--compress `
		--ultra `
		--memory=128MiB `
		/tmp/$UncompressedTarName

	/usr/bin/mv --force /tmp/$CompressedTarName "$BaseLocation/$CompressedTarName"

	Write-Host "`t * Remove base tarball..."

	/usr/bin/rm "$BaseLocation/$UncompressedTarName"
}

Export-ModuleMember -Function Convert-Image