Get Azure endpoint server from DHCP client

It is more efficient and cross-distribution safe to use the hooks function
from dhclient to obtain the Azure endpoint server (DHCP option 245).

This is done by providing shell scritps that are called by the hooks
infrastructure of both dhclient and NetworkManager.  The hooks then
invoke 'cloud-init dhclient-hook' that maintains json data
with the dhclient options in
/run/cloud-init/dhclient.hooks/<interface>.json .

The azure helper then pulls the value from
/run/cloud-init/dhclient.hooks/<interface>.json file(s). If that file does
not exist or the value is not present, it will then fall back to the
original method of scraping the dhcp client lease file.

1 files changed, 50 insertions, 0 deletions

diff --git a/cloudinit/dhclient_hook.py b/cloudinit/dhclient_hook.py
new file mode 100644
index 00000000..9dcbe39c
--- /dev/null
+++ b/cloudinit/dhclient_hook.py
@@ -0,0 +1,50 @@
+#!/usr/bin/python
+# vi: ts=4 expandtab
+
+import os
+
+from cloudinit.atomic_helper import atomic_write_json
+from cloudinit import log as logging
+from cloudinit import stages
+
+LOG = logging.getLogger(__name__)
+
+
+class LogDhclient(object):
+
+    def __init__(self, cli_args):
+        self.hooks_dir = self._get_hooks_dir()
+        self.net_interface = cli_args.net_interface
+        self.net_action = cli_args.net_action
+        self.hook_file = os.path.join(self.hooks_dir,
+                                      self.net_interface + ".json")
+
+    @staticmethod
+    def _get_hooks_dir():
+        i = stages.Init()
+        return os.path.join(i.paths.get_runpath(), 'dhclient.hooks')
+
+    def check_hooks_dir(self):
+        if not os.path.exists(self.hooks_dir):
+            os.makedirs(self.hooks_dir)
+        else:
+            # If the action is down and the json file exists, we need to
+            # delete the file
+            if self.net_action is 'down' and os.path.exists(self.hook_file):
+                os.remove(self.hook_file)
+
+    @staticmethod
+    def get_vals(info):
+        new_info = {}
+        for k, v in info.items():
+            if k.startswith("DHCP4_") or k.startswith("new_"):
+                key = (k.replace('DHCP4_', '').replace('new_', '')).lower()
+                new_info[key] = v
+        return new_info
+
+    def record(self):
+        envs = os.environ
+        if self.hook_file is None:
+            return
+        atomic_write_json(self.hook_file, self.get_vals(envs))
+        LOG.debug("Wrote dhclient options in %s", self.hook_file)