borg-cygwin

• Borg: v1.1.8
• Cygwin: latest online

Based on the work of Billy Charlton and digidream, scripting mostly done in bash, for obvious reasons.

This creates a standard Windows installer for Borg Backup on 64bit (and untested 32bit) Windows 7 and above.

• Borg install itself will only be ~85MB and require about 300MB on disk
• Tested on Windows 8.1 64-bit

WARNING - This is a WIP, which technically works, but needs testing and, you know, shit can still hit the fan.

Don't hold me responsible for that. As said, working on it.

Bugs

• The x86 insatller will suggest "C:\Program Files" instead of "C:\Program Files (x86)". You should switch that on installation till it gets fixed.
• ACL is not tested, as for my kind of backup it’s irrelevant.
• Updating verisons is not tested yet.

---

Running Borg

You can find a premade installer, for both x86 and x86_64 here. Or just build it yourself, have a look at the Build Borg Installer section.

I can't state how important it is to install and run the proper bitness for your system. While 64bit on 32bit systems won't run I presume, 32bit on 64bit will just run fine until you want to utilize something like vssadmin or shadowcopies, as in a 32bit bash environment the required libraries/services are unavailible!

After Installation of the release pachage you should find a cygwin small environment in the Borg installation folder. There is also a backupscript.example file, you can use as a start point. I suggest to use the SYSTEM user to perform local backups, as there should not be any permission issues.

To get a shell as SYSTEM user utilize psexec from PsTools on Microsoft Systinternals. They come in 32bit and 64bit versions, use the proper one for your windows version and run

psexec64 -i -s "C:\Program Files\Borg\bin\mintty.exe" -e "C:\Program Files\Borg\bin\bash.exe" --login

To get a nice little bash shell as SYSTEM user. Be careful, this is the point where you can do pretty much everything, including breaking your machine.

# generate keys for borg backup (no passphrase)
ssh-keygen -t ed25519
# get your public key to insert into the remote machine
cat .ssh/id_ed25519.pub
# connect to your target machine to get its key to the known_hosts
ssh borgbackup@example.com -p 2022 echo
# create your borg repo
# you may want to read the borg doc
export BORG_REPO=ssh://username@example.com:2022/~/backup/main
export BORG_PASSPHRASE='XYZl0ngandsecurepa_55_phrasea&&123'
borg init --encryption=repokey-blake2

# copy the example backupscript as SYSTEM user
cp -rf /backupscript.example /backupscript
# just to be sure
chmod 700 /backupscript
# /backupscript is now SYSTEM owned, to edit it with e.g. Notepad++.
# You may have to close Notepad++, if it's already running as non SYSTEM user
"`cygpath 'C:\Program Files\Notepad++'`/Notepad++" "`cygpath -w /backupscript`" &

You want to edit (use an editor with linux line endings support like Notepad++) the backupscript to stop your services (if any) and add your directories you want to backup. This script contains code to create and mount (or link in the windows world) a shadow copy to a given directory, perform the backup and destroy the shadow. I reccomend using SHADOWC_PATH=`cygpath "C:\\ShadowC"` and then e.g. ${SHADOWC_PATH/Users} as a backup path in borg create command.

backupscript:

#!/bin/bash
PS=`cygpath -S`"/WindowsPowerShell/v1.0/powershell.exe"
NET=`cygpath -S`"/net.exe"
CMD=`cygpath -S`"/cmd.exe"

# Setting this, so the repo does not need to be given on the commandline:
export BORG_REPO=ssh://username@example.com:2022/~/backup/main

# Setting this, so you won't be asked for your repository passphrase:
export BORG_PASSPHRASE='XYZl0ngandsecurepa_55_phrasea&&123'

#Stop / Start Services 
function services_stop {
	: #Empty functions are bad in bash, remove me, when soemthing's in here
#	$NET stop mysql
}
function services_start {
	: #Empty functions are bad in bash, remove me, when soemthing's in here
#	$NET start mysql
}

function vss_create {
	SHADOWID1=$(vss_create_shadow "C:\\")
	vss_mount_shadow $SHADOWID1 "C:\\ShadowC"
}
function vss_delete {
	vss_remove_shadow $SHADOWID1 "C:\\ShadowC"
}

function borg_backup {
SHADOWC_PATH=`cygpath "C:\\ShadowC"`
borg create                         \
    --verbose                       \
    --filter AME                    \
    --list                          \
    --stats                         \
    --show-rc                       \
    --compression lz4               \
                                    \
    ::'{hostname}-{now}'            \
    ${SHADOWC_PATH}/Users           \
	
}

function borg_prune {
borg prune                          \
    --list                          \
    --prefix '{hostname}-'          \
    --show-rc                       \
    --keep-daily    7               \
    --keep-weekly   4               \
    --keep-monthly  6               \
	
}

#Helper Functions
vss_create_shadow () {
	PSC="\$s1 = (Get-WmiObject -List Win32_ShadowCopy).Create(\"$1\", \"ClientAccessible\"); Write-Host \$s1.ShadowID -NoNewLine"
	$PS -Command "$PSC"
}

vss_mount_shadow () {
	PSC="\$s2 = Get-WmiObject Win32_ShadowCopy | Where-Object { \$_.ID -eq \"$1\" }; \$d  = \$s2.DeviceObject + '\'; Write-Host \$d -NoNewLine"
	DEVICEOBJECT=`$PS -Command "$PSC"`
	cmd /c mklink /d $2 "$DEVICEOBJECT"
}

vss_remove_shadow () {
	cmd /c rmdir /q $2
	PSC="\$s2 = Get-WmiObject Win32_ShadowCopy | Where-Object { \$_.ID -eq \"$1\" }; \$s2.Delete()"
	$PS -Command "$PSC"
}

#Execute Backup
services_stop
trap 'services_start' INT TERM
vss_create
trap 'services_start; vss_delete' INT TERM
services_start
trap 'vss_delete' INT TERM
borg_backup
vss_delete
trap - INT TERM
borg_prune

Try the initial backup by executing /backupscript, and if it works out you may create a windows planned task executing the backupscript.bat as SYSTEM user. This will call /backupscript in the user environement.

---

Build Borg Installer

• The only prerequisite is NSIS installed, available at http://nsis.sourceforge.net/Download
• About 3 GB free disk space required to build installer

Create the build environment by using bootstrap.bat You then may proceed to run build_installer_64.bat and/or build_installer_32.bat, to create the run environment and the corresponding installer.

The install script first builds borg inside temporary build/ARCH subfolder, then installs a much smaller release version into the run/ARCH subfolder. Built packages are copied over, unnecessary files removed (still room for improvement), and then NSIS is run and put into dist folder.

Tested with CygWin 2.10.0, borgbackup 1.1.8 on Windows 8.1 64-bit.