make-iscsi-rootfs

#!/bin/sh

set -eu

PROGNAME=$(basename $0)
BASEDIR=$(cd $(dirname $0); pwd)

COPY_BOOT=n
ISCSI_PORTAL=
ISCSI_TARGET=
ISCSI_INITIATOR=

help() {
    cat <<EOF >&2
Usage: $PROGNAME [options]

Help Options:
  -h, --help

Required Options:
  -b, --boot
    Copy /boot into iSCSI storage

  -p, --portal <PORTAL-IPADDR>
    Target IP address

  -t, --target <TARGET-IQN>
    Target IQN

  -i, --initiator <INITIATOR-IQN>
    Initiator IQN

Description:
  $PROGNAME creates rootfs in a specified iSCSI storage in accordance with steps
  described in the following page:

    Net boot (PXE + iSCSI) with a RaspberryPi 3 - darknao's stuff
      https://stuff.drkn.ninja/post/2016/11/08/Net-boot-(PXE-iSCSI)-with-a-RaspberryPi-3

  The open-iscsi package will be installed onto the local machine and the
  open-iscsi systemd service is started and enabled.  Before starting the
  service, The value of InitiatorName in /etc/iscsi/initiatorname.iscsi is
  replaced with the value of the --initiator option.

  initrd.img-\$(uname -r) containing open-iscsi modules is created in /boot
  in the local filesystem.  It's necessary to mount the iSCSI storage in boot.

  The iSCSI storage is formatted with \`mkfs.ext4 -F\`.  And then files in the
  local filesystem are copied into it.

Examples:
  For MMC boot:

    \$ $PROGNAME -p 10.1.2.3 -t iqn.2019-03.example.nas:iscsi:target \\
        -i iqn.2019-03.example.rpi:iscsi:initiator

  For PXE boot:

    \$ $PROGNAME -b -p 10.1.2.3 -t iqn.2019-03.example.nas:iscsi:target \\
        -i iqn.2019-03.example.rpi:iscsi:initiator

Bugs:
  open-iscsi in Raspbian/Stretch has a bug at 2019-03-17, and it has not
  fixed, yet:

    https://bugs.launchpad.net/ubuntu/+source/open-iscsi/+bug/1566468/

  Workaround:

    \$ sudo sed -i s/^ib_iser/#ib_iser/ /lib/modules-load.d/open-iscsi.conf
EOF
    exit 0
}

confirm() {
    read -p "$1" ANSWER
    if [ "$ANSWER" != y ]; then
        exit 0
    fi
}

error() {
    echo "$1" >&2
    exit 1
}

while [ $# -gt 0 ]
do
    case "$1" in
        '-h' | '--help')
            help
            ;;
        '-b' | '--boot')
            COPY_BOOT=y
            shift
            ;;
        '-p' | '--portal')
            ISCSI_PORTAL="$2"
            shift 2
            ;;
        '-t' | '--target')
            ISCSI_TARGET="$2"
            shift 2
            ;;
        '-i' | '--initiator')
            ISCSI_INITIATOR="$2"
            shift 2
            ;;
    esac
done

if [ -z "$ISCSI_PORTAL" ]; then
    error "--portal is required"
fi

if [ -z "$ISCSI_TARGET" ]; then
    error "--target is required"
fi

if [ -z "$ISCSI_INITIATOR" ]; then
    error "--initiator is required"
fi

HOSTNAME=$(hostname)
KERNEL_VERION=$(uname -r)

cat <<EOF
HOSTNAME       : $HOSTNAME
KERNEL_VERSION : $KERNEL_VERION
ISCSI_PORTAL   : $ISCSI_PORTAL
ISCSI_TARGET   : $ISCSI_TARGET
ISCSI_INITIATOR: $ISCSI_INITIATOR

EOF

echo "Installing open-iscsi..."
sudo mkdir -p /etc/iscsi
echo "InitiatorName=$ISCSI_INITIATOR" | sudo tee /etc/iscsi/initiatorname.iscsi
sudo apt-get update -qq
sudo apt-get install -y -qq --no-install-recommends open-iscsi initramfs-tools
# Disable to load ib_iser.
# https://bugs.launchpad.net/ubuntu/+source/open-iscsi/+bug/1566468/comments/14
sudo sed -i s/^ib_iser/#ib_iser/ /lib/modules-load.d/open-iscsi.conf
sudo systemctl restart open-iscsi || error "Failed to start open-iscsi service"

sleep 1
echo "Conneting to $ISCSI_TARGET..."
sudo iscsiadm -m discovery -p $ISCSI_PORTAL -t sendtargets
sudo iscsiadm -m node -p $ISCSI_PORTAL -T $ISCSI_TARGET -l || \
    error "Failed to connect to $ISCSI_TARGET"

sleep 1
DEV=$(ls /dev/disk/by-path/ip-$ISCSI_PORTAL*$ISCSI_TARGET-lun-0 2>/dev/null)
test -n "$DEV" || error "Failed to attach iSCSI storage"

echo "Updating initramfs..."
sudo touch /etc/iscsi/iscsi.initramfs
sudo rm -f /boot/initrd.img-*
sudo update-initramfs -v -k $KERNEL_VERION -c

echo "Creating a GPT partition on $DEV..."
sudo parted -s $DEV mklabel gpt  # will remove all partitions on the disk
sudo parted -s $DEV mkpart root 0% 100%

# Wait 1 second for the partition to be accessible
sleep 1

PART=$DEV-part1

echo "Formatting $PART with ext4..."
sudo mkfs.ext4 -F $PART
UUID=$(sudo blkid -o value -s UUID $PART)

echo "Copying files..."
sudo mount $PART /mnt
DIRS=$(/bin/ls -I dev -I lost+found -I media -I mnt -I proc -I run -I sys -I tmp /)
sudo cp -afv $DIRS /mnt/
sudo mkdir -p /mnt/dev /mnt/media /mnt/mnt /mnt/proc /mnt/run /mnt/sys /mnt/tmp
if [ "$COPY_BOOT" = y ]; then
    sudo cp -afv /boot /mnt/
else
    sudo mkdir -p /mnt/boot
fi
sudo umount $PART

sudo iscsiadm -m node -u

if which raspi-config >/dev/null; then
    PXEBOOT_SHARED_FOLDER=$(cat /proc/cpuinfo | grep Serial | rev | cut -c 1-8 | rev)
else
    PXEBOOT_SHARED_FOLDER="path/to/boot"
fi

cat <<EOF
Done.

You need to update /etc/fstab in the iSCSI LUN by hand:

  sudo iscsiadm -m node -p $ISCSI_PORTAL -T $ISCSI_TARGET -l
  sudo mount /dev/disk/by-uuid/$UUID /mnt

  # Update the device field for the root partition with
  # UUID=$UUID
  sudo nano /mnt/etc/fstab

  sudo umount /mnt
  sudo iscsiadm -m node -u

You also need to add the following kernel parameters in order to mount the iSCSI
LUN at boot time:

  ISCSI_TARGET_IP=$ISCSI_PORTAL
  ISCSI_TARGET_NAME=$ISCSI_TARGET
  ISCSI_INITIATOR=$ISCSI_INITIATOR
  
Copy files in /boot to an appropriate location if you like to use PXE boot:

  sudo mount.cifs //nas/pxeboot/$PXEBOOT_SHARED_FOLDER /mnt
  sudo cp -afv /boot/* /mnt/
  sudo umount /mnt

EOF