path: root/builder/dnbd3-rootfs/hooks/prepare-root-partition.sh

#!/usr/bin/env bash
# region imports
source '/usr/lib/rebash/core.sh'
core.import "/usr/lib/openslx/tools.sh"
core.import exceptions
core.import utils
core.import logging
# endregion
exceptions.activate
( # subshell for variable scoping
logging.set_commands_level debug
logging.set_level debug

source /etc/openslx

# region find writable partition
if ! persistent_device=$(tools.find_block_device \
    "$SLX_WRITABLE_DEVICE_IDENTIFIER")
then
    logging.warn "Failed to find unique device with identifier" \
        "'${SLX_WRITABLE_DEVICE_IDENTIFIER}'; matched devices:" \
        "'${persistent_device}'"
fi

# persistent storage on a filesystem (e.g. usb stick)
# writable_device="$(losetup --find)"
#dd if=/dev/zero of=persistent_storage.img bs=1k count=1000
#losetup "$writable_device" persistent_storage.img
#persistent='P'

# TODO move somewhere else
#tmp_device="$(tools.find_block_device \
    #'$SLX_TMP_PARTITION_IDENTIFIER')"

#if [ -n $tmp_device ]; then
    #mount --type auto "$tmp_device" "$NEWROOT/tmp"
#fi

persistent='N' # 'P' for persistent storage, 'N' for not persistent
if [ -n "$persistent_device" ]; then
    writable_device="$persistent_device"
    if [ "$SLX_WRITABLE_DEVICE_PERSISTENT" = "yes" ]; then
        persistent='P'
    fi
else
    ramdisk_size="$SLX_RAMDISK_SIZE"
    if [ "$ramdisk_size" = "" ]; then
        ramdisk_size="$(awk '/MemTotal/ {print $2}' /proc/meminfo)"
    fi
    # NOTE: If the kernel modul "brd" is compiled into current kernel we can't
    # configure ram disk size dynamically. In this case it have to be
    # configured via kernel command line: "brd.rd_size=SITE_IN_KILOBYTE"
    # statically:
    #! rmmod brd 2>/dev/null
    #modprobe brd max_part=1 rd_size="$ramdisk_size"
    #writable_device='/dev/ram0'
    ramdisk_location="$(mktemp)"
    dd of="$ramdisk_location" seek="$ramdisk_size" count=0 1>/dev/null
    writable_device="$(losetup --find)"
    losetup "$writable_device" "$ramdisk_location"
    #
    persistent='N'
fi


# endregion
# region connect dnbd3
IFS_backup="$IFS"
IFS=","
return_code=1
for host in ${SLX_DNBD3_SERVERS}; do
    logging.info "Trying host '$host'."
    if systemd-preserve-process-marker dnbd3-client --host "$host" --image \
        "${SLX_DNBD3_IMAGE}" --device "$SLX_DNBD3_DEVICE" \
        --rid "$SLX_DNBD3_RID"
    then
        return_code=0
        break
    fi
done
IFS="$IFS_backup"

if [[ $return_code != 0 ]]; then
    logging.warn "Failed to connect '${SLX_DNBD3_IMAGE}' from" \
        "one of '$SLX_DNBD3_SERVERS' to '$SLX_DNBD3_DEVICE'."
    exit 1
fi
# endregion
# region scan partitions
read_only_device=""
if utils.dependency_check qemu-img && ! qemu-img info \
    "$SLX_DNBD3_DEVICE" | grep 'file format: raw'
then
    read_only_device="$(container-unpack-xmount "$SLX_DNBD3_DEVICE")"
else
    # Workaround to detect partitions on raw disks can be omitted when the
    # dnbd3 kernel module supports it (like the nbd kernel module with
    # parameter "max_part").
    loop_device="$(losetup --find)"
    losetup "$loop_device" "$SLX_DNBD3_DEVICE" --partscan
    read_only_device="$loop_device"
    touch "$read_only_device"
    udevadm settle
fi
# Fail fast if no device could be determined.
[ -z "$read_only_device" ] && exit 1
# endregion
# region find read-only partition
if [ -z "$SLX_SYSTEM_PARTITION_PREPARATION_SCRIPT" ]; then
    read_only_partition="$(tools.find_block_device \
        "$SLX_SYSTEM_PARTITION_IDENTIFIER" "$read_only_device")"
else
    eval "$SLX_SYSTEM_PARTITION_PREPARATION_SCRIPT"
fi
if [[ ! $? || -z "$read_only_partition" ]]; then
    logging.error "Failed to find unique device with identifier" \
        "\"${SLX_SYSTEM_PARTITION_IDENTIFIER}\"; matched devices:" \
        "\"${read_only_partition}\""
    exit 1
fi
# endregion

logging.info "Using read-only partition: $read_only_partition"
logging.info "Using writable device $writable_device, persistency: $persistent"

# combine devices with device mapper
device-add-write-layer "root" "$read_only_partition" "$writable_device" \
    "$persistent"

); result=$?; exceptions.deactivate; [[ $result == 0 ]] || exit 1
# region vim modline

# vim: set tabstop=4 shiftwidth=4 expandtab:
# vim: foldmethod=marker foldmarker=region,endregion:

# endregion