WIP: using stevedore to load image handler automatically.

nova/conf/xenserver.py

@@ -471,6 +471,11 @@
 * ``vlan_interface``
 * ``ovs_integration_bridge``
 """),
+    cfg.StrOpt('image_glance_store',
+        default='',
+        help="""
+"""),
+
     # TODO(dharinic): Make this, a stevedore plugin
     cfg.StrOpt('image_upload_handler',
         default='nova.virt.xenapi.image.glance.GlanceStore',
@@ -484,18 +489,6 @@
 store for use. image_upload_handler takes in a value for the Dom0
 plugin driver. This driver is then called to uplaod images to the
 GlanceStore.
-"""),
-    cfg.StrOpt('image_download_handler',
-        default='nova.virt.xenapi.image.glance.GlanceStore',
-        help="""
-The plugin driver used to handle image downloads.
-
-Provide a string value representing a plugin driver required to
-handle the image downloading from Glance.
-
-Images from Glance need to be downloaded to XenServer and create
-disk from the image. This driver is called to download images and
-create disk.
 """),
 ]
 

nova/virt/xenapi/image/glanceStore.py

@@ -0,0 +1,33 @@
+# Copyright 2017 Citrix Systems
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import abc
+
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class glanceStore(object):
+    """Base class for glance store used to upload/download images.
+    """
+
+    @abc.abstractmethod
+    def download_image(self, context, session, instance, image_id):
+        """Download image from glance and create disk from image.
+        """
+
+    @abc.abstractmethod
+    def upload_image(self, context, session, instance, image_id, vdi_uuids):
+        """create image from disk and upload to glance.
+        """

nova/virt/xenapi/image/vdiStream.py

@@ -0,0 +1,66 @@
+# Copyright 2016 Citrix Systems
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+""" This class will handle image data in a streaming way.
+"""
+
+
+from os_xenapi.client import exception as xenapi_exception
+from os_xenapi.client.image import vdi_handler
+from oslo_log import log as logging
+
+import nova.conf
+from nova import exception
+from nova import image
+from nova.virt.xenapi.image.glanceStore import glanceStore
+from nova.virt.xenapi.image import utils
+
+CONF = nova.conf.CONF
+LOG = logging.getLogger(__name__)
+
+IMAGE_API = image.API()
+
+
+class vdiStream(glanceStore):
+    def download_image(self, context, session, instance, image_id):
+        LOG.debug("in vdiStream.download_image")
+        try:
+            host_url = CONF.xenserver.connection_url
+            image_data = IMAGE_API.download(context, image_id)
+            image_stream = utils.IterableToFileAdapter(image_data)
+            vdis = vdi_handler.stream_to_vdis(context, session,
+                                              instance, host_url,
+                                              data=image_stream)
+        except xenapi_exception.OsXenApiException:
+            raise exception.CouldNotFetchImage(image_id=image_id)
+        return vdis
+
+    def upload_image(self, context, session, instance, image_id, vdi_uuids):
+        try:
+            host_url = CONF.xenserver.connection_url
+            metadata = IMAGE_API.get(context, image_id)
+            metadata['disk_format'] = 'vhd'
+            metadata['container_format'] = "ovf"
+            # set size as zero, so that it will update the size in end basing
+            # on the uploaded data.
+            metadata['size'] = 0
+            image_trunks = vdi_handler.vdis_to_stream(context, session,
+                                                      instance, host_url,
+                                                      vdi_uuids)
+            image_stream = utils.IterableToFileAdapter(image_trunks)
+            IMAGE_API.update(context, image_id, metadata,
+                             data=image_stream)
+        except xenapi_exception.OsXenApiException:
+            raise exception.CouldNotUploadImage(image_id=image_id)

nova/virt/xenapi/vm_utils.py

@@ -22,6 +22,7 @@
 import contextlib
 import math
 import os
+import stevedore
 import time
 import urllib
 from xml.dom import minidom
@@ -1357,8 +1358,10 @@ def _fetch_vhd_image(context, session, instance, image_id):
     LOG.debug("Asking xapi to fetch vhd image %s", image_id,
               instance=instance)
 
-    handler = importutils.import_object(
-        CONF.xenserver.image_download_handler)
+    handler = stevedore.driver.DriverManager(
+        "xenapi.image.glance_store",
+        CONF.xenserver.image_glance_store,
+        invoke_on_load=True).driver
 
     try:
         vdis = handler.download_image(context, session, instance, image_id)

nova/virt/xenapi/vmops.py

@@ -19,6 +19,7 @@
 
 import base64
 import functools
+import stevedore
 import time
 import zlib
 
@@ -38,6 +39,7 @@
 from oslo_utils import units
 import six
 
+from nova.i18n import _LW
 from nova import block_device
 from nova import compute
 from nova.compute import power_state
@@ -152,8 +154,20 @@ def __init__(self, session, virtapi):
 
         LOG.debug("Importing image upload handler: %s",
                   CONF.xenserver.image_upload_handler)
-        self.image_upload_handler = importutils.import_object(
-                                CONF.xenserver.image_upload_handler)
+
+        handler = CONF.xenserver.image_upload_handler
+        try:
+            self.image_upload_handler = stevedore.driver.DriverManager(
+                "xenapi.image.glance_store", handler,
+                invoke_on_load=True).driver
+        except stevedore.exception.NoMatches:
+            self.image_upload_handler = importutils.import_object(
+                handler)
+            LOG.warning(_LW("DEPRECATED: image_upload_handler uses "
+                            "importutils to load %(path)s. This "
+                            "legacy loading style will be removed "
+                            "in the next release."),
+                            {'path': handler})
 
     def agent_enabled(self, instance):
         if CONF.xenserver.disable_agent:

setup.cfg

@@ -27,6 +27,9 @@ packages =
     nova
 
 [entry_points]
+xenapi.image.glance_store =
+    vdi_stream = nova.virt.xenapi.image.vdiStream:vdiStream
+
 oslo.config.opts =
     nova.conf = nova.conf.opts:list_opts