Merge ~mpontillo/maas:version-info-updates-and-triggers into maas:master

[Mike Pontillo]

Trigger and websocket work for controller verison

 * Add triggers for ControllerInfo model. (Only fire triggers
   if the version was updated.)
 * Add version information to Controller handler.
 * Add version reporting to controller refresh.
 * Add version display on controller details page.
 * Refactor trigger addition code to add register_triggers() method.
 * Drive-by fix to process_sys_info() to prevent updating fields
   that did not change.

[Andres Rodriguez (andreserl)]

quick comment :)

[Mike Pontillo (mpontillo)]

Quick reply; thanks.

[Lee Trager (ltrager)]

Looks good just one question below.

review: Needs Information

[Mike Pontillo (mpontillo)]

Thanks for taking a look; I've replied to your question inline below.

[Lee Trager (ltrager)]

Thanks for the explanation. LGTM!

review: Approve

diff --git a/src/maasserver/models/node.py b/src/maasserver/models/node.py
index 63e689b..1ec195c 100644
--- a/src/maasserver/models/node.py
+++ b/src/maasserver/models/node.py
@@ -4822,23 +4822,33 @@ class Controller(Node):
     @transactional
     def _process_sys_info(self, response):
         update_fields = []
-        if response['hostname'] != '':
-            self.hostname = response['hostname']
+        hostname = response.get('hostname')
+        if hostname and self.hostname != hostname:
+            self.hostname = hostname
             update_fields.append('hostname')
-        if response['architecture'] != '':
-            self.architecture = response['architecture']
+        architecture = response.get('architecture')
+        if architecture and self.architecture != architecture:
+            self.architecture = architecture
             update_fields.append('architecture')
-        if response['osystem'] != '':
-            self.osystem = response['osystem']
+        osystem = response.get('osystem')
+        if osystem and self.osystem != osystem:
+            self.osystem = osystem
             update_fields.append('osystem')
-        if response['distro_series'] != '':
+        distro_series = response.get('distro_series')
+        if distro_series and self.distro_series != distro_series:
             self.distro_series = response['distro_series']
             update_fields.append('distro_series')
+        maas_version = response.get('maas_version')
+        if maas_version and self.version != maas_version:
+            # Circular imports.
+            from maasserver.models import ControllerInfo
+            ControllerInfo.objects.set_version(self, maas_version)
         # MAAS 2.3+ will send an empty dictionary on purpose, but older
         # versions of the MAAS rack will send real data (and it might arrive
         # in a more timely manner than the UpdateInterfaces call from the
         # NetworksMonitoringService).
-        if response['interfaces'] != {}:
+        interfaces = response.get('interfaces', {})
+        if len(interfaces) > 0:
             self.update_interfaces(response['interfaces'])
         if len(update_fields) > 0:
             self.save(update_fields=update_fields)
diff --git a/src/maasserver/static/partials/node-details.html b/src/maasserver/static/partials/node-details.html
index ccaffa0..66619a1 100755
--- a/src/maasserver/static/partials/node-details.html
+++ b/src/maasserver/static/partials/node-details.html
@@ -321,6 +321,13 @@
                                       aria-label="A region controller controls MAAS services like DNS and runs the database.

A rack controller controls hosts and images and runs network services
like DHCP for connected VLANs."
                                       data-ng-show="node.node_type == 4"></i>
                             </dd>
+                            <dt class="two-col">MAAS Version</dt>
+                            <dd class="four-col last-col" data-ng-show="node.version">
+                                {$ node.version $}
+                            </dd>
+                            <dd class="four-col last-col u-text--subtle" data-ng-show="!node.version">
+                                Unknown (&lt; 2.3.0)
+                            </dd>
                         <dt class="two-col" data-ng-show="node.node_type == 2 || node.node_type == 4">Last image sync</dt>
                             <dd class="four-col last-col" data-ng-show="node.node_type == 2 || node.node_type == 4">
                                 {$ node.last_image_sync || 'never' $}
diff --git a/src/maasserver/triggers/__init__.py b/src/maasserver/triggers/__init__.py
index 88323f2..f84a1db 100644
--- a/src/maasserver/triggers/__init__.py
+++ b/src/maasserver/triggers/__init__.py
@@ -29,21 +29,113 @@ def register_procedure(procedure):
         cursor.execute(procedure)
 
 
-def register_trigger(table, procedure, event, params=None, when="after"):
+# Mappings for  (postgres_event_type, maas_notification_type, pg_obj) for
+# trigger notification events. Three conventions are currently in-use in MAAS.
+
+# Event names: create/update/delete.
+# The majority of triggers use this convention; this is the default.
+EVENTS_CUD = (
+    ('insert', 'create', 'NEW'),
+    ('update', 'update', 'NEW'),
+    ('delete', 'delete', 'OLD'),
+)
+
+# Event names: insert/update/delete.
+EVENTS_IUD = (
+    ('insert', 'insert', 'NEW'),
+    ('update', 'update', 'NEW'),
+    ('delete', 'delete', 'OLD'),
+)
+
+# Event names: link/update/unlink.
+EVENTS_LUU = (
+    ('insert', 'link', 'NEW'),
+    ('update', 'update', 'NEW'),
+    ('delete', 'unlink', 'OLD'),
+)
+
+
+def register_triggers(
+        table, event_prefix, params=None, fields=None, events=None,
+        when="after"):
+    """Registers a set of triggers for insert, update, and delete.
+
+    Event names will be determined based on MAAS convention, unless the
+    convention is passed in via the `events` parameter. Predefined conventions
+    in-use in MAAS are provided via the EVENTS_* constants.
+
+    :param table: The table name to create the trigger on.
+    :param event_prefix: The event prefix for the trigger. For example, if
+        the table is maasserver_subnet, 'subnet' might be an appropriate event
+        prefix.
+    :param params: A dictionary of parameters that should be ANDed together to
+        form the initial WHEN clause.
+    :param fields: A list of fields whose values will be checked for changes
+        before the trigger fires. If None is specified, all fields in the row
+        will be checked.
+    :param events: A tuple in the format of the EVENTS_* constants indicating
+        which convention to use for notification names.
+    :param when: When the trigger should fire relative to the row update. The
+        default is AFTER, but postgresql also supports BEFORE and INSTEAD OF.
+    """
+    if events is None:
+        events = EVENTS_CUD
+    for pg_event, maas_event_type, pg_obj in events:
+        event_params = None
+        if params is not None:
+            event_params = {}
+            for key, value in params.items():
+                event_params['%s.%s' % (pg_obj, key)] = value
+        register_trigger(
+            table, '%s_%s_notify' % (event_prefix, maas_event_type),
+            pg_event, event_params, fields, when)
+
+
+def _make_when_clause(is_update, params, fields):
+    """Generates a WHEN clause for the trigger.
+
+    :param is_update: If true, this trigger is for update. (not insert/delete)
+    :param params: A dictionary of parameters that should be ANDed together to
+        form the initial WHEN clause.
+    :param fields: A list of fields whose values will be checked for changes
+        before the trigger fires. If None is specified, all fields in the row
+        will be checked.
+    :return: the WHEN clause to use in the trigger.
+    """
+    when_clause = ''
+    if params is not None or (fields is not None and is_update):
+        if params is None:
+            params = {}
+        if fields is None:
+            fields = []
+        when_clause = 'WHEN ('
+        when_clause += ' AND '.join([
+            "%s = '%s'" % (key, value)
+            for key, value in params.items()
+        ])
+        if is_update and len(fields) > 0:
+            if len(params) > 0:
+                when_clause += " AND ("
+            when_clause += ' OR '.join([
+                "NEW.%s IS DISTINCT FROM OLD.%s" % (field, field)
+                for field in fields
+            ])
+            if len(params) > 0:
+                when_clause += ")"
+        when_clause += ")"
+    return when_clause
+
+
+def register_trigger(
+        table, procedure, event, params=None, fields=None, when="after"):
     """Register `trigger` on `table` if it doesn't exist."""
     # Strip the "maasserver_" off the front of the table name.
     table_name = table
     if table.startswith("maasserver_"):
         table_name = table_name[11:]
     trigger_name = "%s_%s" % (table_name, procedure)
-    if params is not None:
-        filter = 'WHEN (' + ''.join(
-            [
-                "%s = '%s'" % (key, value)
-                for key, value in params.items()
-            ]) + ')'
-    else:
-        filter = ''
+    is_update = (event == "update")
+    when_clause = _make_when_clause(is_update, params, fields)
     trigger_sql = dedent("""\
         DROP TRIGGER IF EXISTS %s ON %s;
         CREATE TRIGGER %s
@@ -58,7 +150,7 @@ def register_trigger(table, procedure, event, params=None, when="after"):
         when.upper(),
         event.upper(),
         table,
-        filter,
+        when_clause,
         procedure,
         )
     with closing(connection.cursor()) as cursor:
diff --git a/src/maasserver/triggers/tests/test_init.py b/src/maasserver/triggers/tests/test_init.py
index a0256c4..3f291cb 100644
--- a/src/maasserver/triggers/tests/test_init.py
+++ b/src/maasserver/triggers/tests/test_init.py
@@ -125,6 +125,9 @@ class TestTriggersUsed(MAASServerTestCase):
         "config_config_update_notify",
         "config_sys_proxy_config_use_peer_proxy_insert",
         "config_sys_proxy_config_use_peer_proxy_update",
+        'controllerinfo_controllerinfo_link_notify',
+        'controllerinfo_controllerinfo_unlink_notify',
+        'controllerinfo_controllerinfo_update_notify',
         "dhcpsnippet_dhcpsnippet_create_notify",
         "dhcpsnippet_dhcpsnippet_delete_notify",
         "dhcpsnippet_dhcpsnippet_update_notify",
diff --git a/src/maasserver/triggers/tests/test_websocket_listener.py b/src/maasserver/triggers/tests/test_websocket_listener.py
index 8877fcc..c40a3c6 100644
--- a/src/maasserver/triggers/tests/test_websocket_listener.py
+++ b/src/maasserver/triggers/tests/test_websocket_listener.py
@@ -18,6 +18,7 @@ from maasserver.enum import (
     NODE_TYPE,
 )
 from maasserver.listener import PostgresListenerService
+from maasserver.models import ControllerInfo
 from maasserver.models.blockdevice import MIN_BLOCK_DEVICE_SIZE
 from maasserver.models.config import Config
 from maasserver.models.node import Node
@@ -36,7 +37,9 @@ from provisioningserver.utils.twisted import (
     FOREVER,
     synchronous,
 )
+from testtools import ExpectedException
 from twisted.internet.defer import (
+    CancelledError,
     DeferredList,
     DeferredQueue,
     inlineCallbacks,
@@ -219,6 +222,108 @@ class TestNodeListener(
             yield listener.stopService()
 
 
+class TestControllerListener(
+        MAASTransactionServerTestCase, TransactionalHelpersMixin):
+    """End-to-end test of both the listeners code and the triggers code."""
+
+    scenarios = (
+        ('rack', {
+            'params': {'node_type': NODE_TYPE.RACK_CONTROLLER},
+            'listener': 'controller',
+        }),
+        ('region_and_rack', {
+            'params': {'node_type': NODE_TYPE.REGION_AND_RACK_CONTROLLER},
+            'listener': 'controller',
+        }),
+        ('region', {
+            'params': {'node_type': NODE_TYPE.REGION_CONTROLLER},
+            'listener': 'controller',
+        }),
+    )
+
+    def set_version(self, controller, version):
+        ControllerInfo.objects.set_version(controller, version)
+
+    def set_interface_update_info(self, controller, interfaces, hints):
+        ControllerInfo.objects.set_interface_update_info(
+            controller, interfaces, hints)
+
+    def delete_controllerinfo(self, controller):
+        ControllerInfo.objects.filter(node=controller).delete()
+
+    @wait_for_reactor
+    @inlineCallbacks
+    def test__calls_handler_on_controllerinfo_insert(self):
+        yield deferToDatabase(register_websocket_triggers)
+        listener = self.make_listener_without_delay()
+        dv = DeferredValue()
+        params = self.params.copy()
+        controller = yield deferToDatabase(self.create_node, params)
+        listener.register(self.listener, lambda *args: dv.set(args))
+        yield listener.startService()
+        try:
+            yield deferToDatabase(
+                self.set_version, controller, factory.make_string())
+            yield dv.get(timeout=2)
+        finally:
+            yield listener.stopService()
+
+    @wait_for_reactor
+    @inlineCallbacks
+    def test__calls_handler_on_controllerinfo_version_update(self):
+        yield deferToDatabase(register_websocket_triggers)
+        listener = self.make_listener_without_delay()
+        dv = DeferredValue()
+        params = self.params.copy()
+        controller = yield deferToDatabase(self.create_node, params)
+        yield deferToDatabase(self.set_version, controller, '')
+        listener.register(self.listener, lambda *args: dv.set(args))
+        yield listener.startService()
+        try:
+            yield deferToDatabase(
+                self.set_version, controller, factory.make_string())
+            yield dv.get(timeout=2)
+        finally:
+            yield listener.stopService()
+
+    @wait_for_reactor
+    @inlineCallbacks
+    def test__skips_notify_on_controllerinfo_interface_update(self):
+        yield deferToDatabase(register_websocket_triggers)
+        listener = self.make_listener_without_delay()
+        dv = DeferredValue()
+        params = self.params.copy()
+        controller = yield deferToDatabase(self.create_node, params)
+        yield deferToDatabase(self.set_version, controller, '')
+        listener.register(self.listener, lambda *args: dv.set(args))
+        yield listener.startService()
+        try:
+            yield deferToDatabase(
+                self.set_interface_update_info, controller, '{]', '{}')
+            with ExpectedException(CancelledError):
+                yield dv.get(timeout=0.2)
+        finally:
+            yield listener.stopService()
+
+    @wait_for_reactor
+    @inlineCallbacks
+    def test__calls_handler_on_controllerinfo_delete(self):
+        yield deferToDatabase(register_websocket_triggers)
+        listener = self.make_listener_without_delay()
+        dv = DeferredValue()
+        params = self.params.copy()
+        controller = yield deferToDatabase(self.create_node, params)
+        yield deferToDatabase(self.set_version, controller, '')
+        listener.register(self.listener, lambda *args: dv.set(args))
+        yield listener.startService()
+        try:
+            yield deferToDatabase(
+                self.delete_controllerinfo, controller)
+            yield dv.get(timeout=2)
+        finally:
+            yield listener.stopService()
+
+
 class TestDeviceWithParentListener(
         MAASTransactionServerTestCase, TransactionalHelpersMixin):
     """End-to-end test of both the listeners code and the triggers code."""
diff --git a/src/maasserver/triggers/websocket.py b/src/maasserver/triggers/websocket.py
index 0e9df27..0ec50e4 100644
--- a/src/maasserver/triggers/websocket.py
+++ b/src/maasserver/triggers/websocket.py
@@ -22,8 +22,11 @@ from maasserver.enum import (
     NODE_TYPE,
 )
 from maasserver.triggers import (
+    EVENTS_IUD,
+    EVENTS_LUU,
     register_procedure,
     register_trigger,
+    register_triggers,
 )
 from maasserver.utils.orm import transactional
 
@@ -1175,21 +1178,27 @@ def register_websocket_triggers():
                 '%s_delete_notify' % proc_name_prefix,
                 '%s_delete' % event_name_prefix,
                 'OLD.system_id'))
-        register_trigger(
-            "maasserver_node",
-            "%s_create_notify" % proc_name_prefix,
-            "insert",
-            {'NEW.node_type': node_type})
-        register_trigger(
-            "maasserver_node",
-            "%s_update_notify" % proc_name_prefix,
-            "update",
-            {'NEW.node_type': node_type})
-        register_trigger(
-            "maasserver_node",
-            "%s_delete_notify" % proc_name_prefix,
-            "delete",
-            {'OLD.node_type': node_type})
+        register_triggers(
+            "maasserver_node", proc_name_prefix, {'node_type': node_type})
+
+    # ControllerInfo notifications
+    register_procedure(
+        render_node_related_notification_procedure(
+            'controllerinfo_link_notify', 'NEW.node_id'))
+    register_procedure(
+        render_node_related_notification_procedure(
+            'controllerinfo_update_notify', 'NEW.node_id'))
+    register_procedure(
+        render_node_related_notification_procedure(
+            'controllerinfo_unlink_notify', 'OLD.node_id'))
+    register_triggers(
+        "maasserver_controllerinfo",
+        "controllerinfo",
+        # Trigger only fires for version information on update; it doesn't
+        # care when the other metadata is updated.
+        fields=('version',),
+        events=EVENTS_LUU
+    )
 
     # Config table
     register_procedure(
@@ -1201,12 +1210,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'config_delete_notify', 'config_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_config", "config_create_notify", "insert")
-    register_trigger(
-        "maasserver_config", "config_update_notify", "update")
-    register_trigger(
-        "maasserver_config", "config_delete_notify", "delete")
+    register_triggers("maasserver_config", "config")
 
     # Device Node types
     register_procedure(
@@ -1218,15 +1222,8 @@ def register_websocket_triggers():
     register_procedure(
         render_device_notification_procedure(
             'device_delete_notify', 'device_delete', 'OLD'))
-    register_trigger(
-        "maasserver_node", "device_create_notify", "insert",
-        {'NEW.node_type': NODE_TYPE.DEVICE})
-    register_trigger(
-        "maasserver_node", "device_update_notify", "update",
-        {'NEW.node_type': NODE_TYPE.DEVICE})
-    register_trigger(
-        "maasserver_node", "device_delete_notify", "delete",
-        {'OLD.node_type': NODE_TYPE.DEVICE})
+    register_triggers(
+        "maasserver_node", "device", {'node_type': NODE_TYPE.DEVICE})
 
     # VLAN table
     register_procedure(
@@ -1238,12 +1235,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'vlan_delete_notify', 'vlan_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_vlan", "vlan_create_notify", "insert")
-    register_trigger(
-        "maasserver_vlan", "vlan_update_notify", "update")
-    register_trigger(
-        "maasserver_vlan", "vlan_delete_notify", "delete")
+    register_triggers("maasserver_vlan", "vlan")
 
     # IPRange table
     register_procedure(
@@ -1255,12 +1247,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'iprange_delete_notify', 'iprange_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_iprange", "iprange_create_notify", "insert")
-    register_trigger(
-        "maasserver_iprange", "iprange_update_notify", "update")
-    register_trigger(
-        "maasserver_iprange", "iprange_delete_notify", "delete")
+    register_triggers("maasserver_iprange", "iprange")
 
     # Neighbour table
     register_procedure(
@@ -1272,12 +1259,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'neighbour_delete_notify', 'neighbour_delete', 'OLD.ip'))
-    register_trigger(
-        "maasserver_neighbour", "neighbour_create_notify", "insert")
-    register_trigger(
-        "maasserver_neighbour", "neighbour_update_notify", "update")
-    register_trigger(
-        "maasserver_neighbour", "neighbour_delete_notify", "delete")
+    register_triggers("maasserver_neighbour", "neighbour")
 
     # StaticRoute table
     register_procedure(
@@ -1289,12 +1271,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'staticroute_delete_notify', 'staticroute_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_staticroute", "staticroute_create_notify", "insert")
-    register_trigger(
-        "maasserver_staticroute", "staticroute_update_notify", "update")
-    register_trigger(
-        "maasserver_staticroute", "staticroute_delete_notify", "delete")
+    register_triggers("maasserver_staticroute", "staticroute")
 
     # Fabric table
     register_procedure(
@@ -1306,12 +1283,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'fabric_delete_notify', 'fabric_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_fabric", "fabric_create_notify", "insert")
-    register_trigger(
-        "maasserver_fabric", "fabric_update_notify", "update")
-    register_trigger(
-        "maasserver_fabric", "fabric_delete_notify", "delete")
+    register_triggers("maasserver_fabric", "fabric")
 
     # Space table
     register_procedure(
@@ -1323,12 +1295,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'space_delete_notify', 'space_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_space", "space_create_notify", "insert")
-    register_trigger(
-        "maasserver_space", "space_update_notify", "update")
-    register_trigger(
-        "maasserver_space", "space_delete_notify", "delete")
+    register_triggers("maasserver_space", "space")
 
     # Subnet table
     register_procedure(
@@ -1340,12 +1307,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'subnet_delete_notify', 'subnet_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_subnet", "subnet_create_notify", "insert")
-    register_trigger(
-        "maasserver_subnet", "subnet_update_notify", "update")
-    register_trigger(
-        "maasserver_subnet", "subnet_delete_notify", "delete")
+    register_triggers("maasserver_subnet", "subnet")
 
     # Subnet node notifications
     register_procedure(
@@ -1421,15 +1383,8 @@ def register_websocket_triggers():
     register_procedure(
         STATIC_IP_ADDRESS_DOMAIN_NOTIFY % (
             'ipaddress_domain_delete_notify', 'OLD.id'))
-    register_trigger(
-        "maasserver_staticipaddress",
-        "ipaddress_domain_insert_notify", "insert")
-    register_trigger(
-        "maasserver_staticipaddress",
-        "ipaddress_domain_update_notify", "update")
-    register_trigger(
-        "maasserver_staticipaddress",
-        "ipaddress_domain_delete_notify", "delete")
+    register_triggers(
+        "maasserver_staticipaddress", "ipaddress_domain", events=EVENTS_IUD)
 
     # IP range subnet notifications
     register_procedure(
@@ -1438,15 +1393,8 @@ def register_websocket_triggers():
         IP_RANGE_SUBNET_UPDATE_NOTIFY % 'iprange_subnet_update_notify')
     register_procedure(
         IP_RANGE_SUBNET_DELETE_NOTIFY % 'iprange_subnet_delete_notify')
-    register_trigger(
-        "maasserver_iprange",
-        "iprange_subnet_insert_notify", "insert")
-    register_trigger(
-        "maasserver_iprange",
-        "iprange_subnet_update_notify", "update")
-    register_trigger(
-        "maasserver_iprange",
-        "iprange_subnet_delete_notify", "delete")
+    register_triggers(
+        "maasserver_iprange", "iprange_subnet", events=EVENTS_IUD)
 
     # Pod notifications
     register_procedure(
@@ -1457,15 +1405,7 @@ def register_websocket_triggers():
             BMC_TYPE.POD, BMC_TYPE.POD, BMC_TYPE.BMC))
     register_procedure(
         POD_DELETE_NOTIFY % ('pod_delete_notify', BMC_TYPE.POD))
-    register_trigger(
-        "maasserver_bmc",
-        "pod_insert_notify", "insert")
-    register_trigger(
-        "maasserver_bmc",
-        "pod_update_notify", "update")
-    register_trigger(
-        "maasserver_bmc",
-        "pod_delete_notify", "delete")
+    register_triggers("maasserver_bmc", "pod", events=EVENTS_IUD)
 
     # Node pod notifications
     register_procedure(
@@ -1475,15 +1415,7 @@ def register_websocket_triggers():
             'node_pod_update_notify', BMC_TYPE.POD, BMC_TYPE.POD))
     register_procedure(
         NODE_POD_DELETE_NOTIFY % ('node_pod_delete_notify', BMC_TYPE.POD))
-    register_trigger(
-        "maasserver_node",
-        "node_pod_insert_notify", "insert")
-    register_trigger(
-        "maasserver_node",
-        "node_pod_update_notify", "update")
-    register_trigger(
-        "maasserver_node",
-        "node_pod_delete_notify", "delete")
+    register_triggers("maasserver_node", "node_pod", events=EVENTS_IUD)
 
     # DNSData table
     register_procedure(
@@ -1496,15 +1428,8 @@ def register_websocket_triggers():
     register_procedure(
         DNSDATA_DOMAIN_NOTIFY % (
             'dnsdata_domain_delete_notify', 'OLD.dnsresource_id'))
-    register_trigger(
-        "maasserver_dnsdata",
-        "dnsdata_domain_insert_notify", "insert")
-    register_trigger(
-        "maasserver_dnsdata",
-        "dnsdata_domain_update_notify", "update")
-    register_trigger(
-        "maasserver_dnsdata",
-        "dnsdata_domain_delete_notify", "delete")
+    register_triggers(
+        "maasserver_dnsdata", "dnsdata_domain", events=EVENTS_IUD)
 
     # DNSResource table
     register_procedure(
@@ -1515,15 +1440,8 @@ def register_websocket_triggers():
     register_procedure(
         DNSRESOURCE_DOMAIN_NOTIFY % (
             'dnsresource_domain_delete_notify', 'OLD'))
-    register_trigger(
-        "maasserver_dnsresource",
-        "dnsresource_domain_insert_notify", "insert")
-    register_trigger(
-        "maasserver_dnsresource",
-        "dnsresource_domain_update_notify", "update")
-    register_trigger(
-        "maasserver_dnsresource",
-        "dnsresource_domain_delete_notify", "delete")
+    register_triggers(
+        "maasserver_dnsresource", "dnsresource_domain", events=EVENTS_IUD)
 
     # Domain table
     register_procedure(
@@ -1542,12 +1460,7 @@ def register_websocket_triggers():
             'domain_delete_notify', 'domain_delete', 'OLD.id'))
     register_trigger(
         "maasserver_domain", "domain_node_update_notify", "update")
-    register_trigger(
-        "maasserver_domain", "domain_create_notify", "insert")
-    register_trigger(
-        "maasserver_domain", "domain_update_notify", "update")
-    register_trigger(
-        "maasserver_domain", "domain_delete_notify", "delete")
+    register_triggers("maasserver_domain", "domain")
 
     # MAC static ip address table, update to linked domain via dnsresource
     register_procedure(
@@ -1573,12 +1486,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'zone_delete_notify', 'zone_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_zone", "zone_create_notify", "insert")
-    register_trigger(
-        "maasserver_zone", "zone_update_notify", "update")
-    register_trigger(
-        "maasserver_zone", "zone_delete_notify", "delete")
+    register_triggers("maasserver_zone", "zone")
 
     # Service table
     register_procedure(
@@ -1590,12 +1498,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'service_delete_notify', 'service_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_service", "service_create_notify", "insert")
-    register_trigger(
-        "maasserver_service", "service_update_notify", "update")
-    register_trigger(
-        "maasserver_service", "service_delete_notify", "delete")
+    register_triggers("maasserver_service", "service")
 
     # Tag table
     register_procedure(
@@ -1607,12 +1510,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'tag_delete_notify', 'tag_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_tag", "tag_create_notify", "insert")
-    register_trigger(
-        "maasserver_tag", "tag_update_notify", "update")
-    register_trigger(
-        "maasserver_tag", "tag_delete_notify", "delete")
+    register_triggers("maasserver_tag", "tag")
 
     # Node tag link table
     register_procedure(
@@ -1647,12 +1545,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'user_delete_notify', 'user_delete', 'OLD.id'))
-    register_trigger(
-        "auth_user", "user_create_notify", "insert")
-    register_trigger(
-        "auth_user", "user_update_notify", "update")
-    register_trigger(
-        "auth_user", "user_delete_notify", "delete")
+    register_triggers("auth_user", "user")
 
     # Events table
     register_procedure(
@@ -1928,12 +1821,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'sshkey_delete_notify', 'sshkey_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_sshkey", "sshkey_create_notify", "insert")
-    register_trigger(
-        "maasserver_sshkey", "sshkey_update_notify", "update")
-    register_trigger(
-        "maasserver_sshkey", "sshkey_delete_notify", "delete")
+    register_triggers("maasserver_sshkey", "sshkey")
 
     # SSL key table, update to linked user.
     register_procedure(
@@ -1957,12 +1845,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'dhcpsnippet_delete_notify', 'dhcpsnippet_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_dhcpsnippet", "dhcpsnippet_create_notify", "insert")
-    register_trigger(
-        "maasserver_dhcpsnippet", "dhcpsnippet_update_notify", "update")
-    register_trigger(
-        "maasserver_dhcpsnippet", "dhcpsnippet_delete_notify", "delete")
+    register_triggers("maasserver_dhcpsnippet", "dhcpsnippet")
 
     # PackageRepository table
     register_procedure(
@@ -1977,15 +1860,7 @@ def register_websocket_triggers():
         render_notification_procedure(
             'packagerepository_delete_notify', 'packagerepository_delete',
             'OLD.id'))
-    register_trigger(
-        "maasserver_packagerepository", "packagerepository_create_notify",
-        "insert")
-    register_trigger(
-        "maasserver_packagerepository", "packagerepository_update_notify",
-        "update")
-    register_trigger(
-        "maasserver_packagerepository", "packagerepository_delete_notify",
-        "delete")
+    register_triggers("maasserver_packagerepository", "packagerepository")
 
     # Node type change.
     register_procedure(node_type_change())
@@ -2002,12 +1877,7 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'notification_delete_notify', 'notification_delete', 'OLD.id'))
-    register_trigger(
-        "maasserver_notification", "notification_create_notify", "insert")
-    register_trigger(
-        "maasserver_notification", "notification_update_notify", "update")
-    register_trigger(
-        "maasserver_notification", "notification_delete_notify", "delete")
+    register_triggers("maasserver_notification", "notification")
 
     # NotificationDismissal table.
     register_procedure(
@@ -2028,6 +1898,4 @@ def register_websocket_triggers():
     register_procedure(
         render_notification_procedure(
             'script_delete_notify', 'script_delete', 'OLD.id'))
-    register_trigger('metadataserver_script', 'script_create_notify', 'insert')
-    register_trigger('metadataserver_script', 'script_update_notify', 'update')
-    register_trigger('metadataserver_script', 'script_delete_notify', 'delete')
+    register_triggers('metadataserver_script', 'script')
diff --git a/src/maasserver/websockets/handlers/controller.py b/src/maasserver/websockets/handlers/controller.py
index ca85333..6edc6f0 100644
--- a/src/maasserver/websockets/handlers/controller.py
+++ b/src/maasserver/websockets/handlers/controller.py
@@ -23,7 +23,9 @@ class ControllerHandler(MachineHandler):
     class Meta(MachineHandler.Meta):
         abstract = False
         queryset = node_prefetch(
-            Controller.controllers.all().prefetch_related("interface_set"))
+            Controller.controllers.all().prefetch_related("interface_set"),
+            'controllerinfo'
+        )
         allowed_methods = [
             'list',
             'get',
@@ -89,6 +91,7 @@ class ControllerHandler(MachineHandler):
 
     def dehydrate(self, obj, data, for_list=False):
         data = super().dehydrate(obj, data, for_list=for_list)
+        data["version"] = obj.version
         data["vlan_ids"] = [
             interface.vlan_id
             for interface in obj.interface_set.all()
diff --git a/src/maasserver/websockets/handlers/node.py b/src/maasserver/websockets/handlers/node.py
index 12bb3c3..5014fa8 100644
--- a/src/maasserver/websockets/handlers/node.py
+++ b/src/maasserver/websockets/handlers/node.py
@@ -45,10 +45,10 @@ from metadataserver.enum import RESULT_TYPE
 from provisioningserver.tags import merge_details_cleanly
 
 
-def node_prefetch(queryset):
+def node_prefetch(queryset, *args):
     return (
         queryset
-        .select_related('boot_interface', 'owner', 'zone', 'domain')
+        .select_related('boot_interface', 'owner', 'zone', 'domain', *args)
         .prefetch_related('blockdevice_set__iscsiblockdevice')
         .prefetch_related('blockdevice_set__physicalblockdevice')
         .prefetch_related('blockdevice_set__virtualblockdevice')
diff --git a/src/maasserver/websockets/handlers/tests/test_controller.py b/src/maasserver/websockets/handlers/tests/test_controller.py
index 111ed57..ad628e9 100644
--- a/src/maasserver/websockets/handlers/tests/test_controller.py
+++ b/src/maasserver/websockets/handlers/tests/test_controller.py
@@ -7,6 +7,7 @@ __all__ = []
 
 from maasserver.enum import NODE_TYPE
 from maasserver.forms import ControllerForm
+from maasserver.models import ControllerInfo
 from maasserver.testing.factory import factory
 from maasserver.testing.testcase import MAASServerTestCase
 from maasserver.websockets.base import dehydrate_datetime
@@ -96,6 +97,15 @@ class TestControllerHandler(MAASServerTestCase):
         handler = ControllerHandler(owner, {})
         self.assertTrue(handler.dehydrate_show_os_info(rack))
 
+    def test_dehydrate_includes_version(self):
+        owner = factory.make_admin()
+        handler = ControllerHandler(owner, {})
+        rack = factory.make_RackController()
+        version = factory.make_string()
+        ControllerInfo.objects.set_version(rack, version)
+        result = handler.list({})
+        self.assertEqual(version, result[0].get('version'))
+
 
 class TestControllerHandlerScenarios(MAASServerTestCase):
 
diff --git a/src/provisioningserver/refresh/__init__.py b/src/provisioningserver/refresh/__init__.py
index a377038..bf05f10 100644
--- a/src/provisioningserver/refresh/__init__.py
+++ b/src/provisioningserver/refresh/__init__.py
@@ -2,6 +2,7 @@
 # GNU Affero General Public License version 3 (see the file LICENSE).
 
 """Functionality to refresh rack controller hardware and networking details."""
+
 import os
 import socket
 import stat
@@ -25,6 +26,7 @@ from provisioningserver.utils.shell import (
     ExternalProcessError,
 )
 from provisioningserver.utils.twisted import synchronous
+from provisioningserver.utils.version import get_maas_version
 
 
 maaslog = get_maas_logger("refresh")
@@ -77,6 +79,7 @@ def get_sys_info():
         'architecture': get_architecture(),
         'osystem': osystem,
         'distro_series': distro_series,
+        'maas_version': get_maas_version(),
         # In MAAS 2.3+, the NetworksMonitoringService is solely responsible for
         # interface update, because interface updates need to include beaconing
         # data. The key and empty dictionary are necessary for backward
diff --git a/src/provisioningserver/refresh/tests/test_refresh.py b/src/provisioningserver/refresh/tests/test_refresh.py
index ff6b759..d03cac1 100644
--- a/src/provisioningserver/refresh/tests/test_refresh.py
+++ b/src/provisioningserver/refresh/tests/test_refresh.py
@@ -25,6 +25,7 @@ from provisioningserver.refresh.maas_api_helper import (
     MD_VERSION,
     SignalException,
 )
+from provisioningserver.utils.version import get_maas_version
 from testtools.matchers import (
     Contains,
     DirExists,
@@ -82,6 +83,7 @@ class TestHelpers(MAASTestCase):
             'architecture': architecture,
             'osystem': osystem,
             'distro_series': distro_series,
+            'maas_version': get_maas_version(),
             'interfaces': {},
             }, Equals(refresh.get_sys_info()))
 
@@ -105,6 +107,7 @@ class TestHelpers(MAASTestCase):
             'architecture': architecture,
             'osystem': osystem,
             'distro_series': distro_series,
+            'maas_version': get_maas_version(),
             'interfaces': {},
             }, Equals(refresh.get_sys_info()))
 
@@ -120,6 +123,7 @@ class TestHelpers(MAASTestCase):
             'architecture': architecture,
             'osystem': '',
             'distro_series': '',
+            'maas_version': get_maas_version(),
             'interfaces': {},
             }, Equals(refresh.get_sys_info()))