reregister node when they come back online

* Nodes are marked offline, then deleted; given enough time. Nodes can
come back for various reasions (i.e. netsplit). When they come back,
have them recreate the node Instance if AWX_AUTO_DEPROVISION_INSTANCES
is True. Otherwise, do nothing. The do nothing case will show up in the
logs as celery job tracebacks as they fail to be self aware.

awx/main/management/commands/provision_instance.py

@@ -2,7 +2,6 @@
 # All Rights Reserved
 
 from awx.main.models import Instance
-from awx.main.utils.pglock import advisory_lock
 from django.conf import settings
 
 from django.db import transaction
@@ -27,15 +26,12 @@ class Command(BaseCommand):
     def _register_hostname(self, hostname):
         if not hostname:
             return
-        with advisory_lock('instance_registration_%s' % hostname):
-            instance = Instance.objects.filter(hostname=hostname)
-            if instance.exists():
-                print("Instance already registered {}".format(instance[0].hostname))
-                return
-            instance = Instance(uuid=self.uuid, hostname=hostname)
-            instance.save()
-        print('Successfully registered instance {}'.format(hostname))
-        self.changed = True
+        (changed, instance) = Instance.objects.register(uuid=self.uuid, hostname=hostname)
+        if changed:
+            print('Successfully registered instance {}'.format(hostname))
+        else:
+            print("Instance already registered {}".format(instance.hostname))
+        self.changed = changed
 
     @transaction.atomic
     def handle(self, **options):

awx/main/managers.py

@@ -8,6 +8,7 @@ from django.db import models
 from django.conf import settings
 
 from awx.main.utils.filters import SmartFilter
+from awx.main.utils.pglock import advisory_lock
 
 ___all__ = ['HostManager', 'InstanceManager', 'InstanceGroupManager']
 
@@ -86,6 +87,20 @@ class InstanceManager(models.Manager):
             return node[0]
         raise RuntimeError("No instance found with the current cluster host id")
 
+    def register(self, uuid=settings.SYSTEM_UUID, hostname=settings.CLUSTER_HOST_ID):
+        with advisory_lock('instance_registration_%s' % hostname):
+            instance = self.filter(hostname=hostname)
+            if instance.exists():
+                return (False, instance[0])
+            instance = self.create(uuid=uuid, hostname=hostname)
+        return (True, instance)
+
+    def get_or_register(self):
+        if settings.AWX_AUTO_DEPROVISION_INSTANCES:
+            return self.register()
+        else:
+            return (False, self.me())
+
     def active_count(self):
         """Return count of active Tower nodes for licensing."""
         return self.all().count()

awx/main/tasks.py

@@ -204,7 +204,9 @@ def handle_setting_changes(self, setting_keys):
 
 @shared_task(bind=True, queue='tower_broadcast_all', base=LogErrorsTask)
 def handle_ha_toplogy_changes(self):
-    instance = Instance.objects.me()
+    (changed, instance) = Instance.objects.get_or_register()
+    if changed:
+        logger.info(six.text_type("Registered tower node '{}'").format(instance.hostname))
     logger.debug(six.text_type("Reconfigure celeryd queues task on host {}").format(self.request.hostname))
     awx_app = Celery('awx')
     awx_app.config_from_object('django.conf:settings')
@@ -234,7 +236,9 @@ def handle_ha_toplogy_worker_ready(sender, **kwargs):
 def handle_update_celery_routes(sender=None, conf=None, **kwargs):
     conf = conf if conf else sender.app.conf
     logger.debug(six.text_type("Registering celery routes for {}").format(sender))
-    instance = Instance.objects.me()
+    (changed, instance) = Instance.objects.get_or_register()
+    if changed:
+        logger.info(six.text_type("Registered tower node '{}'").format(instance.hostname))
     added_routes = update_celery_worker_routes(instance, conf)
     logger.info(six.text_type("Workers on tower node '{}' added routes {} all routes are now {}")
                 .format(instance.hostname, added_routes, conf.CELERY_ROUTES))
@@ -242,7 +246,9 @@ def handle_update_celery_routes(sender=None, conf=None, **kwargs):
 
 @celeryd_after_setup.connect
 def handle_update_celery_hostname(sender, instance, **kwargs):
-    tower_instance = Instance.objects.me()
+    (changed, tower_instance) = Instance.objects.get_or_register()
+    if changed:
+        logger.info(six.text_type("Registered tower node '{}'").format(tower_instance.hostname))
     instance.hostname = 'celery@{}'.format(tower_instance.hostname)
     logger.warn(six.text_type("Set hostname to {}").format(instance.hostname))
 
@@ -310,6 +316,10 @@ def cluster_node_heartbeat(self):
     this_inst = None
     lost_instances = []
 
+    (changed, instance) = Instance.objects.get_or_register()
+    if changed:
+        logger.info(six.text_type("Registered tower node '{}'").format(instance.hostname))
+
     for inst in list(instance_list):
         if inst.hostname == settings.CLUSTER_HOST_ID:
             this_inst = inst