#!/bin/bash
# Copyright 2016 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Deal with a new hostname assignment.

if [ -n "$new_host_name" ] && [ -n "$new_ip_address" ]; then
  # Delete entries with new_host_name or new_ip_address in /etc/hosts.
  sed -i"" '/Added by Google/d' /etc/hosts

  # Add an entry for our new_host_name/new_ip_address in /etc/hosts.
  echo "${new_ip_address} ${new_host_name} ${new_host_name%%.*}  # Added by Google" >> /etc/hosts

  # Add an entry for reaching the metadata server in /etc/hosts.
  echo "169.254.169.254 metadata.google.internal  # Added by Google" >> /etc/hosts
fi

# /sbin/dhclient-scripts in both ubuntu and centos have some problems for us:
#  1) BOUND doesn't always set hostname (e.g. if old_host_name is unset in
#     precise pangolin)
#  2) Using too long of a FQDN as a hostname causes some tools to break in
#     some distros (e.g. ssh-keygen) and hostname tool complains when given
#     a FQDN that is > 64 bytes.
#
# As a result, we set the host name in all circumstances here, to the truncated
# unqualified domain name.

if [ -n "$new_host_name" ]; then
  hostname "${new_host_name%%.*}"

  # If NetworkManager is installed set the hostname with nmcli.
  # to resolve issues with NetworkManager resetting the hostname
  # to the FQDN on DHCP renew.
  nmcli=$(which nmcli 2> /dev/null)
  if [ -x "$nmcli" ]; then
    nmcli general hostname "${new_host_name%%.*}"
  fi

  # Restart rsyslog to update the hostname.
  systemctl=$(which systemctl 2> /dev/null)
  if [ -x "$systemctl" ]; then
    hasrsyslog=$($systemctl | grep rsyslog | cut -f1 -d' ')
    if [ ! -z "$hasrsyslog" ]; then
      $systemctl -q --no-block restart "$hasrsyslog"
    fi
  else
    pkill -HUP syslogd
  fi
fi