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 the type/tags and descriptions/comments of snapper/timeshift snapshots.
• 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
  • bash >4
  • gawk

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

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

• Use rc-config add grub-btrfsd default, to start the grub-btrfsd daemon the next time the system boots.
  • To start grub-btrfsd right now, run rc-service grub-btrfsd start
  • grub-btrfsd automatically watches the snapshot directory of timeshift (/run/timeshift/backup/timeshift-btrfs/snapshots) and updates the grub-menu when a change occurs.
• Currently untested for snapper

2. If you would like grub-btrfs menu to automatically update on system restart/ shutdown: 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' 
   

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

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

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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