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, 10 insertions, 5 deletions

diff --git a/cloudinit/sources/DataSourceAzure.py b/cloudinit/sources/DataSourceAzure.py
index 8c7e8673..a251fe01 100644
--- a/cloudinit/sources/DataSourceAzure.py
+++ b/cloudinit/sources/DataSourceAzure.py
@@ -20,18 +20,17 @@ import base64
 import contextlib
 import crypt
 import fnmatch
+from functools import partial
 import os
 import os.path
 import time
-import xml.etree.ElementTree as ET
-
 from xml.dom import minidom
-
-from cloudinit.sources.helpers.azure import get_metadata_from_fabric
+import xml.etree.ElementTree as ET
 
 from cloudinit import log as logging
 from cloudinit.settings import PER_ALWAYS
 from cloudinit import sources
+from cloudinit.sources.helpers.azure import get_metadata_from_fabric
 from cloudinit import util
 
 LOG = logging.getLogger(__name__)
@@ -107,6 +106,8 @@ def temporary_hostname(temp_hostname, cfg, hostname_command='hostname'):
 
 
 class DataSourceAzureNet(sources.DataSource):
+    FALLBACK_LEASE = '/var/lib/dhcp/dhclient.eth0.leases'
+
     def __init__(self, sys_cfg, distro, paths):
         sources.DataSource.__init__(self, sys_cfg, distro, paths)
         self.seed_dir = os.path.join(paths.seed_dir, 'azure')
@@ -115,6 +116,8 @@ class DataSourceAzureNet(sources.DataSource):
         self.ds_cfg = util.mergemanydict([
             util.get_cfg_by_path(sys_cfg, DS_CFG_PATH, {}),
             BUILTIN_DS_CONFIG])
+        self.dhclient_lease_file = self.paths.cfgs.get('dhclient_lease',
+                                                       self.FALLBACK_LEASE)
 
     def __str__(self):
         root = sources.DataSource.__str__(self)
@@ -226,7 +229,9 @@ class DataSourceAzureNet(sources.DataSource):
         write_files(ddir, files, dirmode=0o700)
 
         if self.ds_cfg['agent_command'] == '__builtin__':
-            metadata_func = get_metadata_from_fabric
+            metadata_func = partial(get_metadata_from_fabric,
+                                    fallback_lease_file=self.
+                                    dhclient_lease_file)
         else:
             metadata_func = self.get_metadata_from_agent
         try: