0k-charms/precise/host/hooks/install.d/40-btrfs.sh

#!/bin/bash

##
## btrfs install
##

#BTRFS_DEVICE=
BTRFS_MOUNT_ROOT=${BTRFS_MOUNT_ROOT:-"/mnt/btrfs-root"}
if [ -z "$BTRFS_DEVICE" ]; then
    echo "You must set a BTRFS_DEVICE environment variable prior to executing this hook."
    exit 1
fi

apt-get install -y btrfs-tools

if [ "$FORCE" != "yes" ]; then
    echo "the following is dangerous code. Please execute with FORCE=yes."
    echo "it DELETES directory /var/lib/docker if you have one."
    exit 1
fi

## "$BTRFS_DEVICE" device should not be mounted
if mount | egrep ^"$BTRFS_DEVICE\s+" >/dev/null 2>&1; then
    umount "$BTRFS_DEVICE" || {
        echo "Can't umount $BTRFS_DEVICE. Aborting script."
        exit 1
    }
    echo "Unmounted $BTRFS_DEVICE."
fi


if egrep ^"$BTRFS_DEVICE\s+" /etc/fstab >/dev/null 2>&1; then
    sed -r -i "\%^$BTRFS_DEVICE\s+%d" /etc/fstab || {
        echo "Couldn't remove device $BTRFS_DEVICE from fstab."
        exit 1
    }
    echo "Removed device $BTRFS_DEVICE from fstab."
fi


## Format the device and add entry in fstab

mkfs.btrfs -f "$BTRFS_DEVICE"

## No need of UID it seems:
# UUID="$(blkid -s UUID $BTRFS_DEVICE -o value)"
# echo "UUID=$UUID    $BTRFS_MOUNT_ROOT    btrfs    defaults,relatime,compress=lzo,space_cache,auto    0    0" >> /etc/fstab
echo "$BTRFS_DEVICE    $BTRFS_MOUNT_ROOT    btrfs    defaults,relatime,compress=lzo,space_cache,auto    0    0" >> /etc/fstab


## Mount point and mount device

mkdir "$BTRFS_MOUNT_ROOT" -p
mount "$BTRFS_MOUNT_ROOT"


if [ -d /var/lib/docker ] ; then
    RESTART_DOCKER=yes
    service docker stop
    ## XXXvlab: moving doesn't work and is not desirable, as we want docker
    ## to setup and detect new underlying btrfs system.
    # mv "/var/lib/docker/"* "$BTRFS_MOUNT_ROOT/var/lib/docker"
    rm -rf /var/lib/docker/*
fi


## Build subvolume structure

for d in /home /var{/{lib,cache,backups}/lxc,/lib/docker} \
               /var/backups/snapshot \
               /srv/datastore{,/config,/data}; do
    mkdir -p "$(dirname "$BTRFS_MOUNT_ROOT$d")"   ## creates parent directory of subvolume
    btrfs subvolume create "$BTRFS_MOUNT_ROOT$d"
    mkdir -p "$d"

    binds=$(cat /etc/fstab | egrep '\s+none\s+' | grep bind | grep -v '^\s+#' | sed -r 's/^\s*([^ ]+).*$/\1/g')
    for b in $binds; do
        if [[ "$BTRFS_MOUNT_ROOT$d/" == "$b/"* ]]; then
            echo "Directory '$d' is already available via bind '$b'."
            continue 2
        fi
    done

    ## Add bind to /etc/fstab
    echo "$BTRFS_MOUNT_ROOT$d    $d  none bind,defaults,auto 0 0" >> /etc/fstab
done


## Mount all binds

mount -a

[ -z "$RESTART_DOCKER" ] || service docker start

## Prevent mlocate from fetching unwanted informations

if [ -e "/etc/updatedb.conf" ]; then
    ## Without this, especially backup host can have 18Go locate database.
    sed -ri 's/^\s*#\s*PRUNENAMES=/PRUNENAMES=/g;s%^(\s*PRUNEPATHS=".*)("\s*$)+%\1 /mnt/btrfs-root /var/backup/lxc /var/backup/snapshot\2%g' /etc/updatedb.conf
fi