1. Add an importer function that will search for a given module in a set of search module 'prefixes'

   that also has a potential set of required attributes.
2. Use this new importer to find the distro class, the userdata handler modules, the config modules
   and the datasource modules, if none can be found error out accordingly.

1 files changed, 11 insertions, 23 deletions

diff --git a/cloudinit/sources/__init__.py b/cloudinit/sources/__init__.py
index 8ab7cf54..42e924b0 100644
--- a/cloudinit/sources/__init__.py
+++ b/cloudinit/sources/__init__.py
@@ -191,31 +191,19 @@ def list_sources(cfg_list, depends, pkg_list):
     LOG.info(("Looking for for data source in: %s,"
               " via packages %s that matches dependencies %s"),
              cfg_list, pkg_list, depends)
-    for ds_coll in cfg_list:
-        ds_name = str(ds_coll)
+    for ds_name in cfg_list:
         if not ds_name.startswith(DS_PREFIX):
             ds_name = '%s%s' % (DS_PREFIX, ds_name)
-        for pkg in pkg_list:
-            pkg_name = []
-            if pkg:
-                # Any package name given, this affects
-                # the lookup path
-                pkg_name.append(str(pkg))
-            pkg_name.append(ds_name)
-            try:
-                mod = importer.import_module(".".join(pkg_name))
-            except ImportError:
-                continue
-            lister = getattr(mod, "get_datasource_list", None)
-            if not lister:
-                continue
-            cls_matches = lister(depends)
-            if not cls_matches:
-                continue
-            src_list.extend(cls_matches)
-            LOG.debug(("Found a match"
-                       " in %s with matches %s"), mod, cls_matches)
-            break
+        m_locs = importer.find_module(ds_name,
+                                      pkg_list,
+                                      ['get_datasource_list'])
+        for m_loc in m_locs:
+            mod = importer.import_module(m_loc)
+            lister = getattr(mod, "get_datasource_list")
+            matches = lister(depends)
+            if matches:
+                src_list.extend(matches)
+                break
     return src_list