Clone a (ploop) openVZ CT with base image dedup

gistfile1.txt

#!/bin/bash

# Clone a (ploop) openVZ CT with base image dedup
# Ex : ./vzclone $CTID | xargs vzctl start 

set -eo pipefail

if [ -z $1 ]; then 
  >&2 echo "Usage: vzclone CTID"
  exit 1
fi

get_ctid() {
  local CTID="$1"
  vzlist ${CTID} -Ho ctid \
  | xargs # xargs to Remove leading and trailing white spaces / tabs when they exist
}

main() {

  local SRC_CT="$1"
  local SRC_CTID=$(get_ctid ${SRC_CT} || echo 0)

  # Exit when CT can't be found
  [[ "${SRC_CTID}" == 0 ]] && exit 3 

  # Get the current nbr of snapshot for SRC CT
  local SNAPSHOTS_NBR=$(ploop snapshot-list -H /vz/private/$SRC_CTID/root.hdd/DiskDescriptor.xml | wc -l)

  # Exit when snapshot-list didn't work
  [[ "${SNAPSHOTS_NBR}" == 0 ]] && exit 3

  # Get the snapshot id so that we can merge it back to the base image when cloning is done 
  local SNAPSHOT_ID="$(uuidgen)"

  # Take a live snapshot of the CT (Should be merged back to parent snapshot after cloning)
  vzctl --quiet snapshot $SRC_CTID \
    --id ${SNAPSHOT_ID} \
    --name cloneProcess \
    --description "Temporary snapshot for clone process" \
    --skip-suspend --skip-config \
  || exit 3

  local SRC_CT_PRIVATE="$(vzlist -Ho private $SRC_CTID)"
  local DEST_CTID=$(date +%s)
  local DEST_CT_PRIVATE="${SRC_CT_PRIVATE/${SRC_CTID}/${DEST_CTID}}"

  # Clone CT conf from SRC to DEST 
  cp /etc/vz/conf/$SRC_CTID.conf /etc/vz/conf/$DEST_CTID.conf \
  || exit 3

  # Unset description, hostname, ip and name in DEST CT 
  for PARAM in IP_ADDRESS HOSTNAME NAME DESCRIPTION; do
    sed -i "s/${PARAM}=\".*\"/${PARAM}=\"\"/" /etc/vz/conf/${DEST_CTID}.conf \
    || exit 3
  done

  # Set hostname to clonedCT in DEST CT
  sed -i "s/HOSTNAME=\".*\"/HOSTNAME=\"clonedCT\"/" /etc/vz/conf/${DEST_CTID}.conf \

  # Create DEST CT folders 
  mkdir -p $DEST_CT_PRIVATE/root.hdd /vz/root/$DEST_CTID \
  || exit 3

  # Hard link base image from SRC to DEST 
  ln $SRC_CT_PRIVATE/root.hdd/root.hdd ${DEST_CT_PRIVATE}/root.hdd/root.hdd \
  || exit 3

  # Copy * from SRC to DEST (except for the hard linked root.hdd : cp -n)
  2>/dev/null cp -nr ${SRC_CT_PRIVATE}/root.hdd ${DEST_CT_PRIVATE}/ || true 

  # Don't if the parent is the base image
  [[ ${SNAPSHOTS_NBR} > 1 ]] && {

    # Merge back the newly created snapshot to parent snapshot for SRC CT
    ploop snapshot-merge -u ${SNAPSHOT_ID} \
      ${SRC_CT_PRIVATE}/root.hdd/DiskDescriptor.xml >/dev/null

    # Delete the newly created snapshot to parent snapshot for DEST CT 
    vzctl --quiet mount $DEST_CTID
    while killall --quiet -0 ext4lazyinit; do sleep 1; done 
    vzctl --quiet umount $DEST_CTID

    ploop snapshot-delete -u "${SNAPSHOT_ID}" \
      ${DEST_CT_PRIVATE}/root.hdd/DiskDescriptor.xml >/dev/null
  }

  echo $DEST_CTID

}

main "${1}"