Add defaults file in snf-image

host/defaults

+# snf-image defaults file
+
+# IMAGE_NAME: Name of the image to use
+# Generally you use the name of the image with the version of the OS included.
+# Examples include:
+#   centos-5.4 debian-4.0 fedora-12
+# IMAGE_NAME=""
+
+# IMAGE_DIR: directory location for disk images
+# ( default is @localstatedir@/cache/ganeti-instance-image )
+# IMAGE_DIR=""
+
+# OVERLAY: overlay of files to be copied to the instance after OS installation.
+# This is useful for situations where you want to copy instance specific
+# configs such as resolv.conf.
+# OVERLAY=""
+
+# ARCH: Define the ARCH of the image to use
+# Use either x86 or x86_64
+# ARCH="x86_64"
+
+# CUSTOMIZE_DIR: a directory containing scripts to customize the installation.
+# The scripts are executed using run-parts
+# By default /etc/ganeti/instance-image/hooks
+# CUSTOMIZE_DIR="/etc/ganeti/instance-image/hooks"
+
+# IMAGE_DEBUG: turn on debugging output for the scripts
+# IMAGE_DEBUG=0
+
+# Paths for needed programs. Uncommend and change the variables below, if you
+# don't want to use the default one.
+# LOSETUP="losetup"
+# KPARTX="kpartx"
+# SFDISK="sfdisk"
+# INSTALL_MBR="install-mbr"
+# if [ "$windows_support" = "yes" ] ; then
+#     PROGRESS_MONITOR="snf-progress-monitor"
+# fi