add sys_cfg option to DataSource:__init__ , populate ds_cfg from it

In order to be able to configure a DataSource via system config
(ie, what is in /etc/cloud/cloud.cfg), we pass this into the DataSource
class.

The DataSource parent class will set up the 'ds_cfg' member based
on the subclass name. So, DataSourceEc2 will get:
  self.ds_cfg = sys_cfg['datasource']['Ec2']
populated for it.

1 files changed, 19 insertions, 3 deletions

diff --git a/cloudinit/DataSource.py b/cloudinit/DataSource.py
index 0bf17b45..350b5015 100644
--- a/cloudinit/DataSource.py
+++ b/cloudinit/DataSource.py
@@ -21,14 +21,30 @@ DEP_FILESYSTEM = "FILESYSTEM"
 DEP_NETWORK = "NETWORK"
 
 import UserDataHandler as ud
+import cloudinit.util as util
 
 class DataSource:
     userdata = None
     metadata = None
     userdata_raw = None
-
-    def __init__(self):
-        pass
+    cfgname = ""
+    # system config (passed in from cloudinit, 
+    # cloud-config before input from the DataSource)
+    sys_cfg = { }
+    # datasource config, the cloud-config['datasource']['__name__']
+    ds_cfg = { }  # datasource config
+
+    def __init__(self,sys_cfg=None):
+        if not self.cfgname:
+            name = str(self.__class__).split(".")[-1]
+            if name.startswith("DataSource"):
+                name = name[len("DataSource"):]
+            self.cfgname = name
+        if sys_cfg:
+            self.sys_cfg = sys_cfg
+
+        self.ds_cfg = util.get_cfg_by_path(self.sys_cfg,
+                          ("datasource",self.cfgname),self.ds_cfg)
 
     def get_userdata(self):
         if self.userdata == None: