fix review comments

net: add render_route comment to document why we added || true to route
statements
DataSourceConfigDrive: Only convert network_json to network_config when 
caller reads network_config attr.  Cache the conversion.

2 files changed, 17 insertions, 3 deletions

diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index 76cd4e8b..2435055b 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -349,6 +349,20 @@ def iface_add_attrs(iface):
 
 
 def render_route(route, indent=""):
+    """ When rendering routes for an iface, in some cases applying a route
+    may result in the route command returning non-zero which produces
+    some confusing output for users manually using ifup/ifdown[1].  To
+    that end, we will optionally include an '|| true' postfix to each
+    route line allowing users to work with ifup/ifdown without using
+    --force option.
+
+    We may at somepoint not want to emit this additional postfix, and
+    add a 'strict' flag to this function.  When called with strict=True,
+    then we will not append the postfix.
+
+    1. http://askubuntu.com/questions/168033/
+             how-to-set-static-routes-in-ubuntu-server
+    """
     content = ""
     up = indent + "post-up route add"
     down = indent + "pre-down route del"
diff --git a/cloudinit/sources/DataSourceConfigDrive.py b/cloudinit/sources/DataSourceConfigDrive.py
index db813f6e..14676f97 100644
--- a/cloudinit/sources/DataSourceConfigDrive.py
+++ b/cloudinit/sources/DataSourceConfigDrive.py
@@ -153,9 +153,6 @@ class DataSourceConfigDrive(openstack.SourceMixin, sources.DataSource):
             LOG.warn("Invalid content in network-data: %s", e)
             self.network_json = None
 
-        if self.network_json:
-            self._network_config = convert_network_data(self.network_json)
-
         return True
 
     def check_instance_id(self):
@@ -164,6 +161,9 @@ class DataSourceConfigDrive(openstack.SourceMixin, sources.DataSource):
 
     @property
     def network_config(self):
+        if self._network_config is None:
+            if self.network_json is not None:
+                self._network_config = convert_network_data(self.network_json)
         return self._network_config