Adding an instance manager.

awx/main/managers.py

@@ -0,0 +1,27 @@
+# Copyright (c) 2014 Ansible, Inc.
+# All Rights Reserved.
+
+from django.conf import settings
+from django.db import models
+from django.utils.functional import cached_property
+
+
+class InstanceManager(models.Manager):
+    """A custom manager class for the Instance model.
+
+    Provides "table-level" methods including getting the currently active
+    instance or role.
+    """
+    @cached_property
+    def me(self):
+        """Return the currently active instance."""
+        return self.get(uuid=settings.SYSTEM_UUID)
+
+    @cached_property
+    def my_role(self):
+        """Return the role of the currently active instance, as a string
+        ('primary' or 'secondary').
+        """
+        if self.me.primary:
+            return 'primary'
+        return 'secondary'

awx/main/models/ha.py

@@ -2,13 +2,16 @@
 # All Rights Reserved.
 
 from django.db import models
+from awx.main.managers import InstanceManager
 
 
 class Instance(models.Model):
     """A model representing an Ansible Tower instance, primary or secondary,
     running against this database.
     """
-    uuid = models.CharField(max_length=40)
+    objects = InstanceManager()
+
+    uuid = models.CharField(max_length=40, unique=True)
     primary = models.BooleanField(default=False)
     created = models.DateTimeField(auto_now_add=True)
     modified = models.DateTimeField(auto_now=True)