if the user provides a uuid and it exists, allow that to tie to the instance, which allows the user to update the instance based on the UUID (includeding updating the hostname) should they choose to do so.

awx/main/managers.py

@@ -12,9 +12,10 @@ from awx.main.utils.pglock import advisory_lock
 from awx.main.utils.common import get_capacity_type
 from awx.main.constants import RECEPTOR_PENDING
 
-___all__ = ['HostManager', 'InstanceManager', 'InstanceGroupManager', 'DeferJobCreatedManager']
+___all__ = ['HostManager', 'InstanceManager', 'InstanceGroupManager', 'DeferJobCreatedManager', 'UUID_DEFAULT']
 
 logger = logging.getLogger('awx.main.managers')
+UUID_DEFAULT = '00000000-0000-0000-0000-000000000000'
 
 
 class DeferJobCreatedManager(models.Manager):
@@ -105,7 +106,7 @@ class InstanceManager(models.Manager):
         """Return the currently active instance."""
         # If we are running unit tests, return a stub record.
         if settings.IS_TESTING(sys.argv) or hasattr(sys, '_called_from_test'):
-            return self.model(id=1, hostname=settings.CLUSTER_HOST_ID, uuid='00000000-0000-0000-0000-000000000000')
+            return self.model(id=1, hostname=settings.CLUSTER_HOST_ID, uuid=UUID_DEFAULT)
 
         node = self.filter(hostname=settings.CLUSTER_HOST_ID)
         if node.exists():
@@ -115,6 +116,7 @@ class InstanceManager(models.Manager):
     def register(self, uuid=None, hostname=None, ip_address=None, node_type='hybrid', defaults=None):
         if not hostname:
             hostname = settings.CLUSTER_HOST_ID
+
         with advisory_lock('instance_registration_%s' % hostname):
             if settings.AWX_AUTO_DEPROVISION_INSTANCES:
                 # detect any instances with the same IP address.
@@ -127,11 +129,21 @@ class InstanceManager(models.Manager):
                         other_inst.save(update_fields=['ip_address'])
                         logger.warning("IP address {0} conflict detected, ip address unset for host {1}.".format(ip_address, other_hostname))
 
-            # Return existing instance that matches hostname
+            # get the instance based on the hostname
             instance = self.filter(hostname=hostname)
+
+            # Check or update the existing uuid
+            if uuid is not None and uuid != UUID_DEFAULT:
+                if self.filter(uuid=uuid).exists():
+                    instance = self.filter(uuid=uuid)
+
+            # Return existing instance
             if instance.exists():
                 instance = instance.get()
                 update_fields = []
+                if instance.hostname != hostname:
+                    instance.hostname = hostname
+                    update_fields.append('hostname')
                 if instance.ip_address != ip_address:
                     instance.ip_address = ip_address
                     update_fields.append('ip_address')

awx/main/models/ha.py

@@ -18,7 +18,7 @@ from solo.models import SingletonModel
 
 from awx import __version__ as awx_application_version
 from awx.api.versioning import reverse
-from awx.main.managers import InstanceManager, InstanceGroupManager
+from awx.main.managers import InstanceManager, InstanceGroupManager, UUID_DEFAULT
 from awx.main.fields import JSONField
 from awx.main.models.base import BaseModel, HasEditsMixin, prevent_search
 from awx.main.models.unified_jobs import UnifiedJob
@@ -59,7 +59,7 @@ class Instance(HasPolicyEditsMixin, BaseModel):
     objects = InstanceManager()
 
     # Fields set in instance registration
-    uuid = models.CharField(max_length=40, default='00000000-0000-0000-0000-000000000000')
+    uuid = models.CharField(max_length=40, default=UUID_DEFAULT)
     hostname = models.CharField(max_length=250, unique=True)
     ip_address = models.CharField(
         blank=True,