Functionality Backported From Flopsie

One of the key features of the upcoming release of Bedrock Linux, Flopsie, is a new union filesystem intended to fix the /etc-issue. This has been backported to Bosco for those who would like to try it out without having to wait for Flopsie's release. Note that this backport has had minimal testing and may be potentially problematic. If you experience problems, rolling back to Bosco's setup is advised.

Note: This filesystem is named "bru". The utility update utility previously known as "bru" will be merged into another utility, tentatively named "pmm". Apologies for the confusion - it is best to get it out of the way now while the project is still in alpha.

Additionally note that this requires support for FUSE either built-in to the kernel or as a readily accessible kernel module.

Upgrade instructions

Make a directory in which to download and compile the necessary components as well as a directory in which to "install" a local development stack.

mkdir -p /tmp/backport/src /tmp/backport/dev

Download the backported version of bru from here and source for the musl libc library from here and FUSE here into /tmp/backport/src. Note that both projects have patches for bru and, at the time of writing, the latest version development (HEAD from git) of both is required. At the time of writing the version of latest stable musl is 0.9.14, and so most likely any later version not including that version most likely will work. For FUSE, bru will require 3.X.

Compile and install musl with the --prefix into the local development stack location.

• cd /tmp/backport/src/musl
• make clean
• ./configure --prefix=/tmp/backport/dev --disable-shared --enable-static
• make
• make install

Compile and install FUSE, again with the --prefix into the local development stack location. Use the musl-gcc wrapper created by musl as the CC.

• cd /tmp/backport/src/fuse-fuse
• make clean
• ./makeconf.sh
• ./configure --prefix=/tmp/backport/dev --disable-shared --enable-static --disable-util --disable-example
• make CC=/tmp/backport/dev/bin/musl-gcc
• make install

Utilize this newly created development stack to compile bru.c. Make the output name brU with a capital "u" to differentiate it from Bosco's bru update utility. In the following release it will just be bru and what is now bru will be merged into a placeholder for pmm.

• cd /tmp/backport/src
• /tmp/backport/dev/bin/musl-gcc -Wall bru.c -o brU -lfuse3

Install brU.

cp /tmp/backport/src/brU /bedrock/sbin/brU

Comment out the share items from your /bedrock/etc/brclients.conf which share files in /etc. This will be setup to be shared with brU directly in brs - keep the list.

Next brU should be added to brs so that it is set up at boot. First, back up brs so that you can undo this later:

cp /bedrock/sbin/brs /bedrock/sbin/brs-backup

Open up /bedrock/sbin/brs in your preferred text editor and add the following:

if [ "$CLIENT" != "bedrock" ]
then
    brc $CLIENT /bedrock/sbin/brU /etc /var/chroot/$CLIENT/etc \
    /var/chroot/bedrock/etc /profile /hostname /hosts /passwd \
    /group /shadow /sudoers /resolv.conf &
fi

after the done in the inner for loop (and just above the final fi in the script). Adjust the arguments after /var/chroot/bedrock/etc to the list of files you would like shared in /etc.

Finally, you need to make sure the FUSE module is modprobe'd. If you compiled your kernel with fuse built-in, you can skip this step. Otherwise, add the following to brs just before the line RESULTS=0:

brc client modprobe fuse

Where client is a client which has a version of modprobe which can load the module. Some distros compress their modules; distros which do not may not have modprobe configured to decompress modules.

At this point you should be good to go - all you need to do is reboot.

Rolling back the backport

If the backport is not working for you, you can roll it back by doing the following:

cp /bedrock/sbin/brs-backup /bedrock/sbin/brs

and then re-adding the commented out /etc items from /bedrock/etc/brclients.conf.