config_drive: ensure the search locations are ordered alphabetically

cloudbaseinit/constant.py

@@ -13,11 +13,12 @@
 #    under the License.
 
 # Config Drive types and possible locations.
-CD_TYPES = {
-    "vfat",    # Visible device (with partition table).
+# This order is respected.
+CD_TYPES = [
     "iso",     # "Raw" format containing ISO bytes.
-}
-CD_LOCATIONS = {
+    "vfat",    # Visible device (with partition table).
+]
+CD_LOCATIONS = [
     # Look into optical devices. Only an ISO format could be
     # used here (vfat ignored).
     "cdrom",
@@ -27,7 +28,7 @@
     # Search through partitions for raw ISO content or through volumes
     # containing configuration drive's content.
     "partition",
-}
+]
 
 POLICY_IGNORE_ALL_FAILURES = "ignoreallfailures"
 

cloudbaseinit/metadata/services/baseconfigdrive.py

@@ -39,31 +39,38 @@ def __init__(self, drive_label, metadata_file,
         self._metadata_file = metadata_file
         self._userdata_file = userdata_file
         self._metadata_path = None
-        self._searched_types = set()
-        self._searched_locations = set()
+        self._searched_types = list()
+        self._searched_locations = list()
 
     def _preprocess_options(self):
-        self._searched_types = set(CONF.config_drive.types)
-        self._searched_locations = set(CONF.config_drive.locations)
+        self._searched_types = sorted(set(CONF.config_drive.types))
+        self._searched_locations = sorted(set(CONF.config_drive.locations))
 
         # Deprecation backward compatibility.
-        if CONF.config_drive.raw_hdd:
-            self._searched_types.add("iso")
-            self._searched_locations.add("hdd")
         if CONF.config_drive.cdrom:
-            self._searched_types.add("iso")
-            self._searched_locations.add("cdrom")
+            self._searched_types.append("iso")
+            self._searched_locations.append("cdrom")
+        if CONF.config_drive.raw_hdd:
+            self._searched_types.append("iso")
+            self._searched_locations.append("hdd")
         if CONF.config_drive.vfat:
-            self._searched_types.add("vfat")
-            self._searched_locations.add("hdd")
+            self._searched_types.append("vfat")
+            self._searched_locations.append("hdd")
 
         # Check for invalid option values.
-        if self._searched_types | CD_TYPES != CD_TYPES:
+        SCD_TYPES = set(CD_TYPES)
+        if set(self._searched_types) | SCD_TYPES != SCD_TYPES:
             raise exception.CloudbaseInitException(
                 "Invalid Config Drive types %s", self._searched_types)
-        if self._searched_locations | CD_LOCATIONS != CD_LOCATIONS:
+        SCD_LOCATIONS = set(CD_LOCATIONS)
+        if set(self._searched_locations) | SCD_LOCATIONS != SCD_LOCATIONS:
             raise exception.CloudbaseInitException(
                 "Invalid Config Drive locations %s", self._searched_locations)
+        # Note(avladu): sort the order of the searched locations
+        # This is needed to be sure that the order is respected
+        # See: https://github.com/cloudbase/cloudbase-init/issues/200
+        self._searched_types = sorted(set(self._searched_types))
+        self._searched_locations = sorted(set(self._searched_locations))
 
     def load(self):
         super(BaseConfigDriveService, self).load()

cloudbaseinit/tests/metadata/services/test_baseconfigdrive.py

@@ -70,17 +70,17 @@ def _test_preprocess_options(self, fail=False):
             "cdrom": False,
             "vfat": True,
             # Deprecated options above.
-            "types": ["vfat", "iso"],
+            "types": ["iso", "vfat"],
             "locations": ["partition"]
         }
         contexts = [testutils.ConfPatcher(key, value, group="config_drive")
                     for key, value in options.items()]
         with contexts[0], contexts[1], contexts[2], \
                 contexts[3], contexts[4]:
             self._config_drive._preprocess_options()
-            self.assertEqual({"vfat", "iso"},
+            self.assertEqual(["iso", "vfat"],
                              self._config_drive._searched_types)
-            self.assertEqual({"hdd", "partition"},
+            self.assertEqual(["hdd", "partition"],
                              self._config_drive._searched_locations)
 
     def test_preprocess_options_fail(self):