💻 grub-btrfs

BTC donation address: 1Lbvz244WA8xbpHek9W2Y12cakM6rDe5Rt

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🔎 Description:

Improves grub by adding "btrfs snapshots" to the grub menu.

You can boot your system on a "snapshot" from the grub menu.
Supports manual snapshots, snapper, timeshift ...

Warning: booting on read-only snapshots can be tricky

If you choose to do it, /var/log or even /var must be on a separate subvolume.
Otherwise, make sure your snapshots are writable.
See this ticket for more info.

This project includes its own solution.
Refer to the documentation.

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✨ What features does grub-btrfs have?

• Automatically list snapshots existing on root partition (btrfs).
• Automatically detect if /boot is in separate partition.
• Automatically detect kernel, initramfs and Intel/AMD microcode in /boot directory on snapshots.
• Automatically create corresponding "menuentry" in grub.cfg
• Automatically detect the type/tags and descriptions/comments of Snapper/Timeshift snapshots.
• Automatically generate grub.cfg if you use the provided Systemd/ OpenRC service.

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🛠️ Installation:

Arch Linux

The package is available in the community repository grub-btrfs

pacman -S grub-btrfs

Gentoo

grub-btrfs is only available in the Gentoo User Repository (GURU) and not in the official Gentoo repository.
If you have not activated the GURU yet, do so by running:

emerge -av app-eselect/eselect-repository 
eselect repository enable guru 
emaint sync -r guru 

If you are using Systemd on Gentoo, make sure the USE-Flag systemd is set. (Either globally in make.conf or in package.use for the package app-backup/grub-btrfs) Without Systemd USE-Flag the OpenRC-daemon of grub-btrfs will be installed.

Emerge grub-btrfs via emerge app-backup/grub-btrfs

Kali Linux

grub-btrfs is available in the Kali Linux repository and can be installed with:

apt install grub-btrfs

Booting into read-only snapshots is fully supported when choosing "btrfs" as file system during a standard Kali Linux installation following this walk-through.

Manual

• Run make install or look into Makefile for instructions on where to put each file.
• Run make help to check what options are available.
• Dependencies:
  • btrfs-progs
  • grub
  • bash >4
  • gawk
  • (only when using the daemon)inotify-tools

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📚 Usage

After installation the grub main menu needs to be generated to make a menuentry for the snapshots sub menu. Depending on the Linux distribution the commands for that are different:

• On Arch Linux or Gentoo use grub-mkconfig -o /boot/grub/grub.cfg.
• On Fedora use grub2-mkconfig -o /boot/grub2/grub.cfg
• On Debian-like distribution update-grub is an alias to grub-mkconfig ...

Once the entry for the sub menu was generated grub-btrfs puts the actual sub menu into the file grub-btrfs.cfg. So to generate snapshot entries in the sub menu it is usually enough to run only the script with sudo /etc/grub.d/41_snapshots-btrfs. Read further below on how to automate this process.

⚙️ Customization:

You have the possibility to modify many parameters in /etc/default/grub-btrfs/config.
For further information see config file or man grub-btrfs

Warning:

Some file locations and command names differ from distribution to distribution. Initially the configuration is set up to work with Arch and Gentoo (and many other distributions) out of the box, which are using the grub-mkconfig command. However, Fedora for example uses a different command, grub2-mkconfig. Edit GRUB_BTRFS_MKCONFIG variable in /etc/default/grub-btrfs/config file to reflect this. (e.g. GRUB_BTRFS_MKCONFIG=/sbin/grub2-mkconfig for Fedora)

On most distributions and installs, the grub installation resides in /boot/grub. If grub is installed in a different place, change the variable GRUB_BTRFS_MKCONFIG in the config file accordingly. For Fedora this is GRUB_BTRFS_GRUB_DIRNAME="/boot/grub2". Also the command to check the grub scripts is different on some system, for Fedora it is GRUB_BTRFS_SCRIPT_CHECK=grub2-script-check

Customization of the grub-btrfsd daemon

Grub-btrfs comes with a daemon script that automatically updates the grub menu when it sees a snapshot being created or deleted in a directory it is given via command line.

The daemon can be configured by passing different command line arguments to it.

Systemd instructions

To edit the arguments that are passed to the daemon, use

sudo systemctl edit --full grub-btrfsd

after that the Daemon must be restarted with

sudo systemctl restart grub-btrfsd 

It is also possible to start the daemon without using systemd for troubleshooting purposes for example. If you want to do this, a running daemon should be stopped with

sudo systemctl stop grub-btrfsd 

Then the daemon can be manually run and played around with using the command /usr/bin/grub-btrfsd. For additional information on the daemon script and its arguments, run grub-btrfsd -h and see man grub-btrfsd

OpenRC instructions

To edit the arguments that are passed to the daemon edit the file /etc/conf.d/grub-btrfsd.
After that restart the daemon with

sudo rc-service grub-btrfsd restart 

It is also possible to start the daemon without using OpenRC for troubleshooting purposes for example. If you want to do this, a running daemon should be stopped with

sudo rc-service grub-btrfsd stop 

Then the daemon can be manually run and played around with using the command grub-btrfsd. For additional information on daemon script and its arguments, run grub-btrfsd -h and see man grub-btrfsd

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🪀 Automatically update grub upon snapshot

Grub-btrfsd is a daemon daemon that watches the snapshot directory for you and updates the grub menu automatically every time a snapshot is created or deleted. By default this daemon watches the directory /.snapshots for changes (creation or deletion of snapshots) and triggers the grub menu creation if a snapshot is found. Therefore, if Snapper is used with its default directory, the daemon can just be started and nothing needs to be configured. For other configurations like Timeshift, or Snapper with a different directory, see further below.

SystemD instructions

To start the daemon run

sudo systemctl start grub-btrfsd

To activate it during system startup, run

sudo systemctl enable grub-btrfsd

💼 Snapshots not in /.snapshots

NOTE: This works also for Timeshift versions < 22.06, the path to watch would be /run/timeshift/backup/timeshift-btrfs/snapshots.

By default the daemon is watching the directory /.snapshots. If the daemon should watch a different directory, it can be edited with

sudo systemctl edit --full grub-btrfsd # for systemd

What should be edited is the /.snapshots-part in the line that says ExecStart=/usr/bin/grub-btrfsd --syslog /.snapshots. So this is what the file should look afterwards:

[Unit]
Description=Regenerate grub-btrfs.cfg

[Service]
Type=simple
LogLevelMax=notice
# Set the possible paths for `grub-mkconfig`
Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
# Load environment variables from the configuration
EnvironmentFile=/etc/default/grub-btrfs/config
# Start the daemon, usage of it is:
# grub-btrfsd [-h, --help] [-t, --timeshift-auto] [-l, --log-file LOG_FILE] SNAPSHOTS_DIR
# SNAPSHOTS_DIR         Snapshot directory to watch, without effect when --timeshift-auto
# Optional arguments:
# -t, --timeshift-auto  Automatically detect Timeshifts snapshot directory
# -l, --log-file        Specify a logfile to write to
# -v, --verbose         Let the log of the daemon be more verbose
# -s, --syslog          Write to syslog
ExecStart=/usr/bin/grub-btrfsd --syslog /path/to/your/snapshot/directory

[Install]
WantedBy=multi-user.target

When done, the service should be restarted with

sudo systemctl restart grub-btrfsd 

🌟 Timeshift >= version 22.06

Newer Timeshift versions create a new directory named after their process ID in /run/timeshift every time they are started. The PID is going to be different every time. Therefore the daemon can not simply watch a directory, it watches /run/timeshift first, if a directory is created it gets Timeshifts current PID, then watches a directory in that newly created directory from Timeshift. Anyhow, to activate this mode of the daemon, --timeshift-auto must be passed to the daemon as a command line argument.

Systemd

To pass --timeshift-auto to grub-btrfsd, the .service-file of grub-btrfsd can be edited with

sudo systemctl edit --full grub-btrfsd # for systemd

The line that says

ExecStart=/usr/bin/grub-btrfsd /.snapshots --syslog

should be edited into

ExecStart=/usr/bin/grub-btrfsd --syslog --timeshift-auto

So the file looks like this, afterwards:

[Unit]
Description=Regenerate grub-btrfs.cfg

[Service]
Type=simple
LogLevelMax=notice
# Set the possible paths for `grub-mkconfig`
Environment="PATH=/sbin:/bin:/usr/sbin:/usr/bin"
# Load environment variables from the configuration
EnvironmentFile=/etc/default/grub-btrfs/config
# Start the daemon, usage of it is:
# grub-btrfsd [-h, --help] [-t, --timeshift-auto] [-l, --log-file LOG_FILE] SNAPSHOTS_DIR
# SNAPSHOTS_DIR         Snapshot directory to watch, without effect when --timeshift-auto
# Optional arguments:
# -t, --timeshift-auto  Automatically detect Timeshifts snapshot directory
# -l, --log-file        Specify a logfile to write to
# -v, --verbose         Let the log of the daemon be more verbose
# -s, --syslog          Write to syslog
ExecStart=/usr/bin/grub-btrfsd --syslog --timeshift-auto

[Install]
WantedBy=multi-user.target

When done, the service must be restarted with

sudo systemctl restart grub-btrfsd # for systemd

Note: You can view your change with systemctl cat grub-btrfsd. To revert all the changes use systemctl revert grub-btrfsd.

❇️ Automatically update grub upon restart/boot:

Look at this comment
Currently not implemented

OpenRC instructions

To start the daemon run

sudo rc-service grub-btrfsd start 

To activate it during system startup, run

sudo rc-config add grub-btrfsd default 

💼 Snapshots not in /.snapshots

NOTE: This works also for Timeshift versions < 22.06, the path to watch would be /run/timeshift/backup/timeshift-btrfs/snapshots.

By default the daemon is watching the directory /.snapshots. If the daemon should watch a different directory, it can be edited by passing different arguments to it. Arguments are passed to grub-btrfsd via the file /etc/conf.d/grub-btrfsd. The variable snapshots defines, where the daemon will watch for snapshots.

After editing, the file should look like this:

# Copyright 2022 Pascal Jaeger
# Distributed under the terms of the GNU General Public License v3

## Where to locate the root snapshots
#snapshots="/.snapshots" # Snapper in the root directory
#snapshots="/run/timeshift/backup/timeshift-btrfs/snapshots" # Timeshift < v22.06
snapshots="/path/to/your/snapshot/directory"

## Optional arguments to run with the daemon
# Possible options are:
# -t, --timeshift-auto  Automatically detect Timeshifts snapshot directory for timeshift >= 22.06
# -l, --log-file        Specify a logfile to write to
# -v, --verbose         Let the log of the daemon be more verbose
# -s, --syslog          Write to syslog
# Uncomment the line to activate the option
optional_args+="--syslog " # write to syslog by default
#optional_args+="--timeshift-auto "
#optional_args+="--log-file /var/log/grub-btrfsd.log "
#optional_args+="--verbose "

After that, the daemon should be restarted with

sudo rc-service grub-btrfsd restart # for openRC

🌟 Timeshift >= version 22.06

Arguments are passed to grub-btrfsd via the file /etc/conf.d/grub-btrfsd. The variable optional_args defines, which optional arguments get passed to the daemon. Uncomment #optional_args+="--timeshift-auto " to pass the command line option --timeshift-auto to it.

After the change, the file should look like this: (Note that there is no need to comment out the snapshots variable. It is ignored when --timeshift-auto is active.)

# Copyright 2022 Pascal Jaeger
# Distributed under the terms of the GNU General Public License v3

## Where to locate the root snapshots
snapshots="/.snapshots" # Snapper in the root directory
#snapshots="/run/timeshift/backup/timeshift-btrfs/snapshots" # Timeshift < v22.06

## Optional arguments to run with the daemon
# Possible options are:
# -t, --timeshift-auto  Automatically detect Timeshifts snapshot directory for timeshift >= 22.06
# -l, --log-file        Specify a logfile to write to
# -v, --verbose         Let the log of the daemon be more verbose
# -s, --syslog          Write to syslog
# Uncomment the line to activate the option
optional_args+="--syslog " # write to syslog by default
optional_args+="--timeshift-auto "
#optional_args+="--log-file /var/log/grub-btrfsd.log "
#optional_args+="--verbose "

After that, the daemon should be restarted with

sudo rc-service grub-btrfsd restart # for openRC

❇️ Automatically update grub upon restart/boot:

If you would like the grub-btrfs menu to automatically update on system restart/ shutdown, just add the following script as /etc/local.d/grub-btrfs-update.stop:

#!/usr/bin/env bash

description="Update the grub btrfs snapshots menu"
name="grub-btrfs-update"

depend()
{
	use localmount
}
	
bash -c 'if [ -s "${GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub-btrfs.cfg" ]; then /etc/grub.d/41_snapshots-btrfs; else {GRUB_BTRFS_MKCONFIG:-grub-mkconfig} -o {GRUB_BTRFS_GRUB_DIRNAME:-/boot/grub}/grub.cfg; fi' 

Make your script executable with sudo chmod a+x /etc/local.d/grub-btrfs-update.stop.

• The extension .stop at the end of the filename indicates to the locald-daemon that this script should be run at shutdown. If you want to run the menu update on system startup instead, rename the file to grub-btrfs-update.start
• Works for Snapper and Timeshift

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Troubleshooting

If there are problems don't hesitate to file an issue.

Version

To help the best we would like to know the version of grub-btrfs used. Please run

sudo /etc/grub.d/41_snapshots-btrfs --version

or

sudo /usr/bin/grub-btrfsd --help

to get the currently running version of grub-btrfs.

Verbose mode of the daemon

If you have problems with the daemon, you can run it with the --verbose-flag. To do so you can run

sudo /usr/bin/grub-btrfsd --verbose --timeshift-auto` (for timeshift)
# or 
sudo /usr/bin/grub-btrfsd /.snapshots --verbose` (for snapper)

Or pass --verbose to the daemon using the Systemd .service-file or the OpenRC conf.d file respectively. (see Daemon installation instructions how to do that)

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Special thanks for assistance and contributions

• Maxim Baz
• Schievel1
• All contributors

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