fetch-basefile

#! /bin/bash

# fetch-basefile, fetch a basefile via ftp or http using classes
#
# (c) Thomas Lange, 2011-2012
#
# Try to download a CLASSNAME.tar.gz (or tgz, or tar.xz,...) from an URL which matches a class name
# The URL must provide a listing of all files in there
# e.g.: FAI_BASEFILEURL=http://fai-project.org/download/basefiles
#
# variables needed: $classes, $FAI, $FAI_BASEFILEURL

FAI_BASEFILEURL=http://fai-project.org/download/basefiles
classes="ABC A123 CENTOS SLC6_ ENTOS5_32 DEBIAN SQUEEZE"
FAI=/dev/shm
mkdir -p $FAI/basefiles
verbose=1

mount_ramdisk() {

    # put ramdisk on config space and download file
    mount -t tmpfs tmpfs $FAI/basefiles # this makes files from NFS invisible
    if [ $? -eq 1]; then
	echo "mount ramdisk onto $FAI/basefiles failed."
	exit 3
    fi
}

[ X$FAI_BASEFILEURL = X ] && exit 0
url=$FAI_BASEFILEURL
[ "$verbose" ] && echo "Fetching basefile from $url"

error=0
found=0
mount=0

while getopts m opt ; do
        case "$opt" in
        m) mount=1 ;;
        esac
done
#shift $(($OPTIND - 1))

# get list of all files at URL
flist=$(lftp -e 'cls;exit' $url 2>/dev/null)

# create a hash like thing
# key (here variable name) is the basename of the file found
# value is the complete filename
for f in $flist; do
  # echo file found: $f
  base=${f%%.*}   # basename is the class name
  eval "found_$base=$f"
done

# reverse order of classes
for c in $classes; do
    revclasses="$c $revclasses"
done

# now search for each class, if a basename matches
for c in $revclasses; do
  id="found_$c"  # prepare for indirect variable name
  if [ X${!id} != X ]; then
      # hash lookup succeeded
      found=1
      [ $mount = 1 ] && mount_ramdisk
      cd $FAI/basefiles || exit 3
      if [ -f ${!id} ]; then
	  echo "${!id} already exists"
	  error=1
	  break
      fi

      echo "Downloading $url/${!id}"
      #  wget -nv $url/${!id}    # creates a new file with suffix .1, .2,.. if file already exists. Bad.
      lftp -e "get $url/${!id};exit" # fails if file already exists. this is nice.
      error=$?
      break
  fi
done

if [ X$found = X0 ]; then
  echo No basefile matching a class name was found at $url
fi

exit $error

# the rest is done by task extrbase using ftar