merging trunk

2 files changed, 37 insertions, 7 deletions

diff --git a/nova/image/__init__.py b/nova/image/__init__.py
index 93d83df24..a27d649d4 100644
--- a/nova/image/__init__.py
+++ b/nova/image/__init__.py
@@ -22,6 +22,7 @@ import nova
 from nova import exception
 from nova import utils
 from nova import flags
+from nova.image import glance as glance_image_service
 
 FLAGS = flags.FLAGS
 
@@ -48,6 +49,8 @@ def get_default_image_service():
     return ImageService()
 
 
+# FIXME(sirp): perhaps this should be moved to nova/images/glance so that we
+# keep Glance specific code together for the most part
 def get_glance_client(image_href):
     """Get the correct glance client and id for the given image_href.
 
@@ -62,7 +65,9 @@ def get_glance_client(image_href):
     """
     image_href = image_href or 0
     if str(image_href).isdigit():
-        glance_client = GlanceClient(FLAGS.glance_host, FLAGS.glance_port)
+        glance_host, glance_port = \
+            glance_image_service.pick_glance_api_server()
+        glance_client = GlanceClient(glance_host, glance_port)
         return (glance_client, int(image_href))
 
     try:
diff --git a/nova/image/glance.py b/nova/image/glance.py
index 61308431d..6e058ab2f 100644
--- a/nova/image/glance.py
+++ b/nova/image/glance.py
@@ -20,6 +20,7 @@
 from __future__ import absolute_import
 
 import datetime
+import random
 
 from glance.common import exception as glance_exception
 
@@ -39,6 +40,21 @@ FLAGS = flags.FLAGS
 GlanceClient = utils.import_class('glance.client.Client')
 
 
+def pick_glance_api_server():
+    """Return which Glance API server to use for the request
+
+    This method provides a very primitive form of load-balancing suitable for
+    testing and sandbox environments. In production, it would be better to use
+    one IP and route that to a real load-balancer.
+
+        Returns (host, port)
+    """
+    host_port = random.choice(FLAGS.glance_api_servers)
+    host, port_str = host_port.split(':')
+    port = int(port_str)
+    return host, port
+
+
 class GlanceImageService(service.BaseImageService):
     """Provides storage and retrieval of disk image objects within Glance."""
 
@@ -51,12 +67,21 @@ class GlanceImageService(service.BaseImageService):
                           GLANCE_ONLY_ATTRS
 
     def __init__(self, client=None):
-        # FIXME(sirp): can we avoid dependency-injection here by using
-        # stubbing out a fake?
-        if client is None:
-            self.client = GlanceClient(FLAGS.glance_host, FLAGS.glance_port)
-        else:
-            self.client = client
+        self._client = client
+
+    def _get_client(self):
+        # NOTE(sirp): we want to load balance each request across glance
+        # servers. Since GlanceImageService is a long-lived object, `client`
+        # is made to choose a new server each time via this property.
+        if self._client is not None:
+            return self._client
+        glance_host, glance_port = pick_glance_api_server()
+        return GlanceClient(glance_host, glance_port)
+
+    def _set_client(self, client):
+        self._client = client
+
+    client = property(_get_client, _set_client)
 
     def index(self, context, filters=None, marker=None, limit=None):
         """Calls out to Glance for a list of images available."""