1 files changed, 101 insertions, 0 deletions
diff --git a/cloudinit/handlers/cc_update_hostname.py b/cloudinit/handlers/cc_update_hostname.py
new file mode 100644
index 00000000..b9d1919a
--- /dev/null
+++ b/cloudinit/handlers/cc_update_hostname.py
@@ -0,0 +1,101 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2011 Canonical Ltd.
+#    Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
+#
+#    Author: Scott Moser <scott.moser@canonical.com>
+#    Author: Juerg Haefliger <juerg.haefliger@hp.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
+
+    (hostname, _fqdn) = util.get_hostname_fqdn(cfg, cloud)
+    try:
+        prev = "%s/%s" % (cloud.get_cpath('data'), "previous-hostname")
+        update_hostname(hostname, prev, log)
+    except Exception:
+        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()