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# vi: ts=4 expandtab
#
# Copyright (C) 2011 Canonical Ltd.
#
# Author: Scott Moser <scott.moser@canonical.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 3, as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import cloudinit.util as util
import subprocess
import errno
from cloudinit.CloudConfig import per_always
frequency = per_always
def handle(name,cfg,cloud,log,args):
if util.get_cfg_option_bool(cfg,"preserve_hostname",False):
log.debug("preserve_hostname is set. not updating hostname")
return
try:
hostname = util.get_cfg_option_str(cfg,"hostname",cloud.get_hostname())
prev ="%s/%s" % (cloud.get_cpath('data'),"previous-hostname")
update_hostname(hostname, prev, log)
except Exception as e:
log.warn("failed to set hostname\n")
raise
# read hostname from a 'hostname' file
# allow for comments and stripping line endings.
# if file doesn't exist, or no contents, return default
def read_hostname(filename, default=None):
try:
fp = open(filename,"r")
lines = fp.readlines()
fp.close()
for line in lines:
hpos = line.find("#")
if hpos != -1:
line = line[0:hpos]
line = line.rstrip()
if line:
return line
except IOError as e:
if e.errno != errno.ENOENT: raise
return default
def update_hostname(hostname, prev_file, log):
etc_file = "/etc/hostname"
hostname_prev = None
hostname_in_etc = None
try:
hostname_prev = read_hostname(prev_file)
except Exception as e:
log.warn("Failed to open %s: %s" % (prev_file, e))
try:
hostname_in_etc = read_hostname(etc_file)
except:
log.warn("Failed to open %s" % etc_file)
update_files = []
if not hostname_prev or hostname_prev != hostname:
update_files.append(prev_file)
if (not hostname_in_etc or
(hostname_in_etc == hostname_prev and hostname_in_etc != hostname)):
update_files.append(etc_file)
try:
for fname in update_files:
util.write_file(fname,"%s\n" % hostname, 0644)
log.debug("wrote %s to %s" % (hostname,fname))
except:
log.warn("failed to write hostname to %s" % fname)
if hostname_in_etc and hostname_prev and hostname_in_etc != hostname_prev:
log.debug("%s differs from %s. assuming user maintained" %
(prev_file,etc_file))
if etc_file in update_files:
log.debug("setting hostname to %s" % hostname)
subprocess.Popen(['hostname', hostname]).communicate()
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