DataSourceCloudStack.patch

--- /usr/lib/python2.7/dist-packages/cloudinit/DataSourceCloudStack.py.old	2012-04-11 03:54:56.000000000 +0000
+++ /usr/lib/python2.7/dist-packages/cloudinit/DataSourceCloudStack.py	2013-09-07 01:01:02.482498743 +0000
@@ -24,6 +24,7 @@
 from cloudinit import log
 import cloudinit.util as util
 from socket import inet_ntoa
+import os
 import time
 import boto.utils as boto_utils
 from struct import pack
@@ -37,20 +38,11 @@
     def __init__(self, sys_cfg=None):
         DataSource.DataSource.__init__(self, sys_cfg)
         # Cloudstack has its metadata/userdata URLs located at
-        # http://<default-gateway-ip>/latest/
-        self.metadata_address = "http://%s/" % self.get_default_gateway()
-
-    def get_default_gateway(self):
-        """ Returns the default gateway ip address in the dotted format
-        """
-        with open("/proc/net/route", "r") as f:
-            for line in f.readlines():
-                items = line.split("\t")
-                if items[1] == "00000000":
-                    # found the default route, get the gateway
-                    gw = inet_ntoa(pack("<L", int(items[2], 16)))
-                    log.debug("found default route, gateway is %s" % gw)
-                    return gw
+        # http://<virtual-router-ip>/latest/
+        vr_addr = get_vr_address()
+        if not vr_addr:
+            raise RuntimeError("No virtual router found!")
+        self.metadata_address = "http://%s/" % (vr_addr)
 
     def __str__(self):
         return "DataSourceCloudStack"
@@ -82,6 +74,72 @@
     def get_availability_zone(self):
         return self.metadata['availability-zone']
 
+def get_default_gateway():
+    # Returns the default gateway ip address in the dotted format.
+    lines = util.load_file("/proc/net/route").splitlines()
+    for line in lines:
+        items = line.split("\t")
+        if items[1] == "00000000":
+            # Found the default route, get the gateway
+            gw = inet_ntoa(pack("<L", int(items[2], 16)))
+            log.debug("Found default route, gateway is %s", gw)
+            return gw
+    return None
+
+
+def get_dhclient_d():
+    # find lease files directory
+    supported_dirs = ["/var/lib/dhclient", "/var/lib/dhcp"]
+    for d in supported_dirs:
+        if os.path.exists(d):
+            log.debug("Using %s lease directory", d)
+            return d
+    return None
+
+
+def get_latest_lease():
+    # find latest lease file
+    lease_d = get_dhclient_d()
+    if not lease_d:
+        return None
+    lease_files = os.listdir(lease_d)
+    latest_mtime = -1
+    latest_file = None
+    for file_name in lease_files:
+        if file_name.endswith(".lease") or file_name.endswith(".leases"):
+            abs_path = os.path.join(lease_d, file_name)
+            mtime = os.path.getmtime(abs_path)
+            if mtime > latest_mtime:
+                latest_mtime = mtime
+                latest_file = abs_path
+    return latest_file
+
+def get_vr_address():
+    # Get the address of the virtual router via dhcp leases
+    # see http://bit.ly/T76eKC for documentation on the virtual router.
+    # If no virtual router is detected, fallback on default gateway.
+    lease_file = get_latest_lease()
+    if not lease_file:
+        log.debug("No lease file found, using default gateway")
+        return get_default_gateway()
+
+    latest_address = None
+    with open(lease_file, "r") as fd:
+        for line in fd:
+            if "dhcp-server-identifier" in line:
+                words = line.strip(" ;\r\n").split(" ")
+                if len(words) > 2:
+                    dhcp = words[2]
+                    log.debug("Found DHCP identifier %s", dhcp)
+                    latest_address = dhcp
+    if not latest_address:
+        # No virtual router found, fallback on default gateway
+        log.debug("No DHCP found, using default gateway")
+        return get_default_gateway()
+    return latest_address
+
+
+
 datasources = [
   (DataSourceCloudStack, (DataSource.DEP_FILESYSTEM, DataSource.DEP_NETWORK)),
 ]
@@ -90,3 +148,5 @@
 # return a list of data sources that match this set of dependencies
 def get_datasource_list(depends):
     return DataSource.list_from_depends(depends, datasources)
+
+