Upstart script to set domain and host name in case they are reset on reboots (OpenVZ VPSes sometimes have that problem).

hostname.conf

# hostname - set system hostname
#
# This script sets the hostname in case it is not set properly.
# This may be the case with OpenVZ VPSes that the provider is not willing to
# provide you a proper hostname for.  Annoying but not unfixabe.
#
# Before using this script make sure that the first stanza in /etc/hosts that
# gives names to the node's primary IP address look as follows:
#
#     123.123.123.123  fully.qualified.name.com  shortname
#
# This script will pick that up and set the domain and host name accordingly.


description     "set system hostname"

start on net-device-up

task

script
  # parse the IPv4 address from the ifconfig stanzas
  primary_ip=$(ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p')

  # get the FQDN from /etc/hosts
  fqdn=$(getent hosts $primary_ip | awk '{print $2}')

  # set the domain and host name from the FQDN
  /bin/domainname $(echo $fqdn | cut -d. -f2-)
  hn=$(echo $fqdn | cut -d. -f1)
  echo $hn > /etc/hostname
  /bin/hostname $hn
end script