pull-images.sh

#!/bin/bash
set -e

cd "$(dirname $(readlink -f "${BASH_SOURCE}"))"
source config.sh

function fetch_checksum() {
  local DISTR=$1
  local URL=$2
  local FILENAME=$3

  wget -q $URL -O ${DISTR}.tmp.sha256
  grep $FILENAME\$ ${DISTR}.tmp.sha256 | awk '{ print $1}'
}

cd $VMFILES/images
for distr in "${!DISTRO_IMAGES[@]}"; do
  echo Downloading \"${distr}\" checksums...
  filename=$(basename ${DISTRO_IMAGES[$distr]})

  chksum=$(fetch_checksum ${distr} ${DISTRO_CHECKSUMS[$distr]} $filename)

  if ! echo "${chksum}  $(basename ${DISTRO_IMAGES[$distr]})" | sha256sum -c; then
    echo "File changed, downloading..."
    wget --show-progress -q ${DISTRO_IMAGES[$distr]} -O ${distr}.tmp

    if echo "${chksum}  ${distr}.tmp" | sha256sum -c; then
      echo Download complete!
      mv ${distr}.tmp $filename
      rm ${distr}.tmp.sha256
    else
      echo Checksums don\'t match...
      rm ${distr}.tmp ${distr}.tmp.sha256
    fi
  else
    echo "Image not changed, skipping."
    rm ${distr}.tmp.sha256
  fi
done