EC2 DescribeImageAttribute by kernel/ramdisk.

Fixes bug 1026898.

Supports kernel/ramdisk attributes for EC2 DescribeImageAttribute API to
display the ID of the kernel/ramdisk associated with the AMI. And adds
test cases to verify this behavior.

Change-Id: I3ea91b95812dcec349b4ff6dc889645a57975278

nova/api/ec2/cloud.py

@@ -1389,10 +1389,26 @@ def _root_device_name_attribute(image, result):
             if result['rootDeviceName'] is None:
                 result['rootDeviceName'] = block_device.DEFAULT_ROOT_DEV_NAME
 
+        def _kernel_attribute(image, result):
+            kernel_id = image['properties'].get('kernel_id')
+            if kernel_id:
+                result['kernel'] = {
+                    'value': ec2utils.image_ec2_id(kernel_id, 'aki')
+                }
+
+        def _ramdisk_attribute(image, result):
+            ramdisk_id = image['properties'].get('ramdisk_id')
+            if ramdisk_id:
+                result['ramdisk'] = {
+                    'value': ec2utils.image_ec2_id(ramdisk_id, 'ari')
+                }
+
         supported_attributes = {
             'blockDeviceMapping': _block_device_mapping_attribute,
             'launchPermission': _launch_permission_attribute,
             'rootDeviceName': _root_device_name_attribute,
+            'kernel': _kernel_attribute,
+            'ramdisk': _ramdisk_attribute,
             }
 
         fn = supported_attributes.get(attribute)

nova/tests/api/ec2/test_cloud.py

@@ -1336,6 +1336,12 @@ def fake_detail(self, context, **kwargs):
         result = describe_image_attribute(self.context, 'ami-00000001',
                                           'launchPermission')
         self.assertEqual([{'group': 'all'}], result['launchPermission'])
+        result = describe_image_attribute(self.context, 'ami-00000001',
+                                          'kernel')
+        self.assertEqual('aki-00000001', result['kernel']['value'])
+        result = describe_image_attribute(self.context, 'ami-00000001',
+                                          'ramdisk')
+        self.assertEqual('ari-00000001', result['ramdisk']['value'])
 
     def test_describe_image_attribute_root_device_name(self):
         describe_image_attribute = self.cloud.describe_image_attribute