Refactor glance id<->internal id conversion for s3

 * Moves nova.image.s3.S3ImageService functions for converting
   between glance ('image_uuid') and internal (db) ids to ec2utils:

       get_image_id => ec2utils.glance_id_to_id
       get_image_uuid => ec2utils.id_to_glance_id

 * Refactors ec2utils.glance_id_to_id to create a new S3Image
   object associating a glance id to an internal id if such a
   mapping does not already exist.  Previously, only calls to
   nova.api.ec2.cloud.CloudController.describe_images would
   add new mappings, but now any attempt to convert a glance id
   to an internal id will succeed, resolving bug 948286.

 * Adds 2 convenience methods to ec2utils, as per bcwaldon:

       ec2_id_to_glance_id
       glance_id_to_ec2_id

 * Since this is a strict refactor and only streamlines existing
   well-tested functionality, this change includes no new tests.

Change-Id: I810afe05223228df1bcc20a0ac688d8c62c472b4

2 files changed, 35 insertions, 19 deletions

diff --git a/nova/api/ec2/cloud.py b/nova/api/ec2/cloud.py
index 81f0c9a7e..a95a0324f 100644
--- a/nova/api/ec2/cloud.py
+++ b/nova/api/ec2/cloud.py
@@ -967,15 +967,14 @@ class CloudController(object):
         kernel_uuid = instance_ref['kernel_id']
         if kernel_uuid is None or kernel_uuid == '':
             return
-        kernel_id = self._get_image_id(context, kernel_uuid)
-        result[key] = ec2utils.image_ec2_id(kernel_id, 'aki')
+        result[key] = ec2utils.glance_id_to_ec2_id(context, kernel_uuid, 'aki')
 
     def _format_ramdisk_id(self, context, instance_ref, result, key):
         ramdisk_uuid = instance_ref['ramdisk_id']
         if ramdisk_uuid is None or ramdisk_uuid == '':
             return
-        ramdisk_id = self._get_image_id(context, ramdisk_uuid)
-        result[key] = ec2utils.image_ec2_id(ramdisk_id, 'ari')
+        result[key] = ec2utils.glance_id_to_ec2_id(context, ramdisk_uuid,
+                                                   'ari')
 
     def describe_instance_attribute(self, context, instance_id, attribute,
                                     **kwargs):
@@ -1173,8 +1172,7 @@ class CloudController(object):
             ec2_id = ec2utils.id_to_ec2_id(instance_id)
             i['instanceId'] = ec2_id
             image_uuid = instance['image_ref']
-            image_id = self._get_image_id(context, image_uuid)
-            i['imageId'] = ec2utils.image_ec2_id(image_id)
+            i['imageId'] = ec2utils.glance_id_to_ec2_id(context, image_uuid)
             self._format_kernel_id(context, instance, i, 'kernelId')
             self._format_ramdisk_id(context, instance, i, 'ramdiskId')
             i['instanceState'] = _state_description(
@@ -1287,16 +1285,17 @@ class CloudController(object):
         max_count = int(kwargs.get('max_count', 1))
         if kwargs.get('kernel_id'):
             kernel = self._get_image(context, kwargs['kernel_id'])
-            kwargs['kernel_id'] = self._get_image_uuid(context, kernel['id'])
+            kwargs['kernel_id'] = ec2utils.id_to_glance_id(context,
+                                                           kernel['id'])
         if kwargs.get('ramdisk_id'):
             ramdisk = self._get_image(context, kwargs['ramdisk_id'])
-            kwargs['ramdisk_id'] = self._get_image_uuid(context,
-                                                        ramdisk['id'])
+            kwargs['ramdisk_id'] = ec2utils.id_to_glance_id(context,
+                                                            ramdisk['id'])
         for bdm in kwargs.get('block_device_mapping', []):
             _parse_block_device_mapping(bdm)
 
         image = self._get_image(context, kwargs['image_id'])
-        image_uuid = self._get_image_uuid(context, image['id'])
+        image_uuid = ec2utils.id_to_glance_id(context, image['id'])
 
         if image:
             image_state = self._get_image_state(image)
@@ -1383,15 +1382,6 @@ class CloudController(object):
             raise exception.ImageNotFound(image_id=ec2_id)
         return image
 
-    # NOTE(bcwaldon): We need access to the image uuid since we directly
-    # call the compute api from this class
-    def _get_image_uuid(self, context, internal_id):
-        return self.image_service.get_image_uuid(context, internal_id)
-
-    # NOTE(bcwaldon): We also need to be able to map image uuids to integers
-    def _get_image_id(self, context, image_uuid):
-        return self.image_service.get_image_id(context, image_uuid)
-
     def _format_image(self, image):
         """Convert from format defined by GlanceImageService to S3 format."""
         i = {}
diff --git a/nova/api/ec2/ec2utils.py b/nova/api/ec2/ec2utils.py
index e44ae287e..1a6bb96bd 100644
--- a/nova/api/ec2/ec2utils.py
+++ b/nova/api/ec2/ec2utils.py
@@ -18,6 +18,7 @@
 
 import re
 
+from nova import db
 from nova import exception
 from nova import flags
 from nova import log as logging
@@ -46,6 +47,31 @@ def image_type(image_type):
     return image_type
 
 
+def id_to_glance_id(context, image_id):
+    """Convert an internal (db) id to a glance id."""
+    return db.s3_image_get(context, image_id)['uuid']
+
+
+def glance_id_to_id(context, glance_id):
+    """Convert a glance id to an internal (db) id."""
+    if glance_id is None:
+        return
+    try:
+        return db.s3_image_get_by_uuid(context, glance_id)['id']
+    except exception.NotFound:
+        return db.s3_image_create(context, glance_id)['id']
+
+
+def ec2_id_to_glance_id(context, ec2_id):
+    image_id = ec2_id_to_id(ec2_id)
+    return id_to_glance_id(context, image_id)
+
+
+def glance_id_to_ec2_id(context, glance_id, image_type='ami'):
+    image_id = glance_id_to_id(context, glance_id)
+    return image_ec2_id(image_id, image_type=image_type)
+
+
 def ec2_id_to_id(ec2_id):
     """Convert an ec2 ID (i-[base 16 number]) to an instance id (int)"""
     try: