support launch index specific user-data

EC2 and openstack provide 'launch_index' in their metadata. This allows
the user to specify cloud-config or multipart mime data that includes the
'Launch-Index' header.

If launch index is available in the metadata service, then:
 * any part that contains a launch index other than the current launch-index
   of this instance will be ignored.
 * any part that does not contain a launch index will be considered as
   for this instance.

If there is no such header, or launch_index is not available in the metadata
service, then no such filtering will be done.

LP: #1023177

1 files changed, 6 insertions, 2 deletions

diff --git a/cloudinit/cloud.py b/cloudinit/cloud.py
index 620b3c07..95e0cfb2 100644
--- a/cloudinit/cloud.py
+++ b/cloudinit/cloud.py
@@ -70,12 +70,16 @@ class Cloud(object):
         return fn
 
     # The rest of thes are just useful proxies
-    def get_userdata(self):
-        return self.datasource.get_userdata()
+    def get_userdata(self, apply_filter=True):
+        return self.datasource.get_userdata(apply_filter)
 
     def get_instance_id(self):
         return self.datasource.get_instance_id()
 
+    @property
+    def launch_index(self):
+        return self.datasource.launch_index
+
     def get_public_ssh_keys(self):
         return self.datasource.get_public_ssh_keys()