novatools call to child zones done

nova/scheduler/zone_manager.py

@@ -0,0 +1,126 @@
+# Copyright (c) 2010 Openstack, LLC.
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+# 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.
+
+"""
+ZoneManager oversees all communications with child Zones.
+"""
+
+import novatools
+import thread
+
+from datetime import datetime
+from eventlet.greenpool import GreenPool
+
+from nova import db
+from nova import flags
+from nova import log as logging
+
+FLAGS = flags.FLAGS
+flags.DEFINE_integer('zone_db_check_interval', 60,
+                    'Seconds between getting fresh zone info from db.')
+flags.DEFINE_integer('zone_failures_to_offline', 3,
+             'Number of consecutive errors before marking zone offline')
+
+
+class ZoneState(object):
+    """Holds the state of all connected child zones."""
+    def __init__(self):
+        self.is_active = True
+        self.name = None
+        self.capabilities = None
+        self.attempt = 0
+        self.last_seen = datetime.min
+        self.last_exception = None
+        self.last_exception_time = None
+ 
+    def update_credentials(self, zone):
+        """Update zone credentials from db"""
+        self.zone_id = zone.id
+        self.api_url = zone.api_url
+        self.username = zone.username
+        self.password = zone.password
+ 
+    def update_metadata(self, zone_metadata):
+        """Update zone metadata after successful communications with
+           child zone."""
+        self.last_seen = datetime.now()
+        self.attempt = 0
+        self.name = zone_metadata["name"]
+        self.capabilities = zone_metadata["capabilities"]
+        self.is_active = True
+
+    def log_error(self, exception):
+        """Something went wrong. Check to see if zone should be
+           marked as offline."""
+        self.last_exception = exception
+        self.last_exception_time = datetime.now()
+        logging.warning(_("%s error talking to zone %s") % (exception,
+            zone.api_url, FLAGS.zone_failures_to_offline))
+
+       self.attempt += 1
+        if self.attempt >= FLAGS.zone_failures_to_offline:
+           self.is_active = False
+           logging.error(_("No answer from zone %s after %d "
+               "attempts. Marking inactive.") % (zone.api_url,
+               FLAGS.zone_failures_to_offline))
+
+def _poll_zone(zone):
+    """Eventlet worker to poll a zone."""
+    logging.debug("_POLL_ZONE: STARTING")
+    os = novatools.OpenStack(zone.username, zone.password, zone.api_url)
+    try:
+        zone.update_metadata(os.zones.info()._info)
+    except Exception, e:
+        zone.log_error(e)
+
+class ZoneManager(object):
+    """Keeps the zone states updated."""
+    def __init__(self):
+        self.last_zone_db_check = datetime.min
+        self.zone_states = {}
+
+    def _refresh_from_db(self, context):
+        """Make our zone state map match the db."""
+        # Add/update existing zones ...
+        zones = db.zone_get_all(context)
+        existing = self.zone_states.keys()
+        db_keys = []
+        for zone in zones:
+            db_keys.append(zone.id)
+            if zone.id not in existing:
+                self.zone_states[zone.id] = ZoneState()
+            self.zone_states[zone.id].update_credentials(zone)
+
+        # Cleanup zones removed from db ...
+        for zone_id in self.zone_states.keys():
+            if zone_id not in db_keys:
+                del self.zone_states[zone_id]
+ 
+    def _poll_zones(self, context):
+        """Try to connect to each child zone and get update."""
+        green_pool = GreenPool()
+        green_pool.imap(_poll_zone, self.zone_states.values())
+
+    def ping(self, context=None):
+        """Ping should be called periodically to update zone status."""
+        logging.debug("ZoneManager PING")
+        diff = datetime.now() - self.last_zone_db_check
+        if diff.seconds >=  FLAGS.zone_db_check_interval:
+            logging.debug("ZoneManager RECHECKING DB ")
+            self.last_zone_db_check = datetime.now()
+            self._refresh_from_db(context)
+        self._poll_zones(context)