Merge lp:~soren/nova/libvirt-reconnect into lp:~hudson-openstack/nova/trunk

[Soren Hansen]

Reconnect to libvirt on broken connection.

If libvirt is restarted, nova-compute gets very sad. This patch makes it detect the failure and reestablish the connection. This is quite handy if one happens to also develop on libvirt.

[Jay Pipes (jaypipes)]

Nice.

review: Approve

[Eric Day (eday)]

lgtm.

review: Approve

=== modified file 'nova/virt/libvirt_conn.py'
--- nova/virt/libvirt_conn.py	2010-08-18 21:14:24 +0000
+++ nova/virt/libvirt_conn.py	2010-08-30 13:06:39 +0000
@@ -84,10 +84,22 @@
 
     @property
     def _conn(self):
-        if not self._wrapped_conn:
+        if not self._wrapped_conn or not self._test_connection():
+            logging.debug('Connecting to libvirt: %s' % self.libvirt_uri)
             self._wrapped_conn = self._connect(self.libvirt_uri, self.read_only)
         return self._wrapped_conn
 
+    def _test_connection(self):
+        try:
+            self._wrapped_conn.getVersion()
+            return True
+        except libvirt.libvirtError as e:
+            if e.get_error_code() == libvirt.VIR_ERR_SYSTEM_ERROR and \
+               e.get_error_domain() == libvirt.VIR_FROM_REMOTE:
+                logging.debug('Connection to libvirt broke')
+                return False
+            raise
+
     def get_uri_and_template(self):
         if FLAGS.libvirt_type == 'uml':
             uri = FLAGS.libvirt_uri or 'uml:///system'