grub-btrfs

This is a version 4.xx of 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 writeable.
See this ticket for more info.

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

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What does grub-btrfs v4.xx do :

• 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 snapper and use snapper's snapshot description if available.
• Automatically generate grub.cfg if you use the provided systemd 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 
emerge --sync 

Now merge grub-btrfs via emerge app-backup/grub-btrfs

Manual

• Run make install or look into Makefile for instructions on where to put each file.
• Dependencies:
  • btrfs-progs
  • grub

NOTE: All distros

Generate your Grub menu after installation for the changes to take effect.
For example:
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 ...

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Customization :

You have the possibility to modify many parameters in /etc/default/grub-btrfs/config.
See config file for more information.

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Automatically update grub :

Systemd

1. If you would like grub-btrfs menu to automatically update when a snapshot is created or deleted:

• Use systemctl enable grub-btrfs.path.
  • grub-btrfs.path automatically (re)generates grub-btrfs.cfg when a modification appears in /.snapshots mount point (by default).
  • If the /.snapshots mount point is already mounted, then use systemctl start grub-btrfs.path to start monitoring.
    Otherwise, the unit will automatically start monitoring when the mount point will be available.
• If your snapshots location aren't mounted in /.snapshots, you must modify grub-btrfs.path unit using
  systemctl edit --full grub-btrfs.path and run systemctl reenable grub-btrfs.path for changes take effect.
  To find out the name of the .mount unit
  use systemctl list-units -t mount.

  • For example: Timeshift mounts its snapshot folder in /run/timeshift/backup/timeshift-btrfs/snapshots.

    Use systemctl edit --full grub-btrfs.path. Then replace the whole block by:

    [Unit]
    Description=Monitors for new snapshots
    DefaultDependencies=no
    Requires=run-timeshift-backup.mount
    After=run-timeshift-backup.mount
    BindsTo=run-timeshift-backup.mount
    
    [Path]
    PathModified=/run/timeshift/backup/timeshift-btrfs/snapshots
    
    [Install]
    WantedBy=run-timeshift-backup.mount
    

    Then save and finally run systemctl reenable grub-btrfs.path for changes take effect.
    Optional:
    If the /run/timeshift/backup/timeshift-btrfs/snapshots mount point is already mounted,
    then use systemctl start grub-btrfs.path to start monitoring.
    Otherwise, the unit will automatically start monitoring when the mount point will be available.

  • You can view your change to systemctl cat grub-btrfs.path.

  • To revert change use systemctl revert grub-btrfs.path.

2. If you would like grub-btrfs menu to automatically update on system restart/shutdown:
   Look at this comment
   Currently not implemented

OpenRC

• There is sadly no similar solution to the systemd service yet.
  As a workaround it is possible to add a script to /etc/local.d to execute the snapshot menu update every time you shut down your system.
  To do so just add the following script as /etc/local.d/grub-btrfs-update.stop

  #!/bin/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' 
  

  If you want to run the menu update on startup instead, rename the file to grub-btrfs-update.start

Warning :

by default, grub-mkconfig command is used.
Might be grub2-mkconfig on some systems (Fedora ...).
Edit GRUB_BTRFS_MKCONFIG variable in /etc/default/grub-btrfs/config file to reflect this.

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Special thanks for assistance and contributions

• Maxim Baz
• Schievel1
• All contributors

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