Wrapper for building all overlays.

wwrebuild

#!/bin/bash

# Author: griznog
# Purpose: Build/update overlays for all nodes.

# Pull in warewulf functions/variables for this node.
[[ -f /warewulf/etc/functions ]] && source /warewulf/etc/functions || exit 1


# Collect an MD5SUM for an entire directory, hopefully in a repeatable way.
function wwovl_md5sum () {
  local ovl=$1
  # Abort early if the overlay doesn't actually exist.
  [[ -d ${WWOVERLAYDIR}/${ovl} ]] || return 1

  cat $(find ${WWOVERLAYDIR}/${ovl} -type f ! -iname ".wwovl_${ovl}_version") | md5sum
}

# Detect changes to the overlay.
function is_overlay_changed () {
  local ovl=$1
  local retval=0 # Assume yes.

  local MD5SUMFILE=${ovl}/MD5SUM
  local VERSIONFILE=${ovl}/rootfs/.wwovl_${ovl}_version

  # Abort early if the overlay doesn't actually exist and use rootfs directory for content.
  [[ -d ${WWOVERLAYDIR}/${ovl}/rootfs ]] || return 1

  # Get previous checksum, seeding the files if not found.
  if [[ -f ${MD5SUMFILE} ]]; then
    local MD5SUM_OLD=$(<${MD5SUMFILE})
  else
    local MD5SUM_OLD=( $(cat $(find ${ovl}/rootfs -type f ! -iname .wwovl_${ovl}_version | sort) | md5sum ) )
    echo echo ${MD5SUM_OLD[0]} > ${MD5SUMFILE}
  fi
    
  # Get previous version, seedin the version file if not found.
  if [[ -f ${VERSIONFILE} ]]; then
    local VERSION_OLD=$(<${VERSIONFILE})
  else
    local VERSION_OLD=0
    echo ${VERSION_OLD} > ${VERSIONFILE}
  fi

  # Collect a current md5sum for the overlay.
  local MD5SUM_NEW=( $(cat $(find ${ovl}/rootfs -type f ! -iname .wwovl_${ovl}_version | sort) | md5sum ) )

  # See if version needs to increment.
  if [[ "${MD5SUM_OLD}" != "${MD5SUM_NEW[0]}" ]]; then
    # There were changes, increment the version and rebuild
    local VERSION_NEW=$(( ${VERSION_OLD} + 1 ))
    echo ${VERSION_NEW} > ${VERSIONFILE}
    echo ${MD5SUM_NEW[0]} > ${MD5SUMFILE}
    retval=0
  else
    # There were no detected changes.
    retval=1
  fi

  return ${retval}
}

function build_overlay () {
  local ovl=$1
  local force=$2
  local retval=0
  local MD5SUMFILE=${ovl}/MD5SUM
  local VERSIONFILE=${ovl}/rootfs/.wwovl_${ovl}_version

  if [[ -d ${WWOVERLAYDIR}/${ovl}/rootfs ]]; then
    if is_overlay_changed ${ovl} || [[ -n ${force} ]]; then
      wwctl overlay build -O ${ovl} > /dev/null 2>&1
      retval=$?
      echo "  ${ovl}: Built version $(<${VERSIONFILE})"
    else
      echo "  ${ovl}: No changes detected, skipping build."
    fi
  else
     echo "  ${ovl} has no rootfs directory, skipping build."
     retval=1
  fi
  return ${retval}
}

# Script starts here

# Find the overlay root location.
WWCONF=/etc/warewulf/warewulf.conf # Yeah, hard coded. But we have to start somewhere.
[[ -f ${WWCONF} ]] || \
  die "Can't find ${WWCONF}"

# See https://github.com/hpcng/warewulf/issues/635 as I'm pretending like that has 
# already been added to WW4.
WWOVERLAYDIR=$(yq ".paths.overlays" < /etc/warewulf/warewulf.conf)

# Overlays are complicated. Do this in steps.
# First, move to overlay directory.
pushd ${WWOVERLAYDIR} > /dev/null 2>&1 || \
  die "Could not find overlay directory: ${WWOVERLAYDIR}"

# Third, the 'wwctl overlay build' command still has some quirks. We need
# it to build individually to be able to do live updates for specific overlays.
  echo "Building standalone overlays..."
  force=''; [[ "$*" =~ .*force.* ]] && force=force
  for ovl in *; do
    # [[ ${ovl} =~ ^system ]] && continue
    # Build the overlay.
    build_overlay ${ovl} ${force} &
  done # | sort
  wait
  echo "... completed building individual overlays."
  echo
popd > /dev/null 2>&1 

# Last, build the merged overlay image used for booting.
if [[ "$*" =~ "merged" ]]; then
  echo -n "Building merged overlays for node booting..."
  wwctl overlay build > /dev/null 2>&1
  echo "...done."
else
  echo "Use '$(basename $0) --merged' to also build merged overlays for initrd."
fi