diff --git a/ironic/objects/fields.py b/ironic/objects/fields.py
index 5c2565dc2d..c1add2c630 100644
--- a/ironic/objects/fields.py
+++ b/ironic/objects/fields.py
@@ -14,6 +14,8 @@
 #    under the License.
 
 import ast
+import hashlib
+import inspect
 import six
 
 from oslo_versionedobjects import fields as object_fields
@@ -33,6 +35,37 @@ class StringField(object_fields.StringField):
     pass
 
 
+class StringAcceptsCallable(object_fields.String):
+    @staticmethod
+    def coerce(obj, attr, value):
+        if callable(value):
+            value = value()
+        return super(StringAcceptsCallable, StringAcceptsCallable).coerce(
+            obj, attr, value)
+
+
+class StringFieldThatAcceptsCallable(object_fields.StringField):
+    """Custom StringField object that allows for functions as default
+
+    In some cases we need to allow for dynamic defaults based on configuration
+    options, this StringField object allows for a function to be passed as a
+    default, and will only process it at the point the field is coerced
+    """
+
+    AUTO_TYPE = StringAcceptsCallable()
+
+    def __repr__(self):
+        default = self._default
+        if (self._default != object_fields.UnspecifiedDefault and
+                callable(self._default)):
+            default = "%s-%s" % (
+                self._default.__name__,
+                hashlib.md5(inspect.getsource(
+                    self._default).encode()).hexdigest())
+        return '%s(default=%s,nullable=%s)' % (self._type.__class__.__name__,
+                                               default, self._nullable)
+
+
 class DateTimeField(object_fields.DateTimeField):
     pass
 
diff --git a/ironic/objects/node.py b/ironic/objects/node.py
index 6bb03d5c87..b73eed8798 100644
--- a/ironic/objects/node.py
+++ b/ironic/objects/node.py
@@ -117,15 +117,10 @@ class Node(base.IronicObject, object_base.VersionedObjectDictCompat):
 
         'extra': object_fields.FlexibleDictField(nullable=True),
 
-        'network_interface': object_fields.StringField(
-            nullable=False, default=_default_network_interface()),
+        'network_interface': object_fields.StringFieldThatAcceptsCallable(
+            nullable=False, default=_default_network_interface),
     }
 
-    def __init__(self, context=None, **kwargs):
-        self.fields['network_interface']._default = (
-            _default_network_interface())
-        super(Node, self).__init__(context, **kwargs)
-
     def _validate_property_values(self, properties):
         """Check if the input of local_gb, cpus and memory_mb are valid.
 
diff --git a/ironic/tests/unit/objects/test_fields.py b/ironic/tests/unit/objects/test_fields.py
index a9d736ac9f..1291c619c8 100644
--- a/ironic/tests/unit/objects/test_fields.py
+++ b/ironic/tests/unit/objects/test_fields.py
@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import hashlib
+import inspect
 
 from ironic.common import exception
 from ironic.objects import fields
@@ -61,3 +63,45 @@ class TestFlexibleDictField(test_base.TestCase):
         # nullable
         self.field = fields.FlexibleDictField(nullable=True)
         self.assertEqual({}, self.field.coerce('obj', 'attr', None))
+
+
+class TestStringFieldThatAcceptsCallable(test_base.TestCase):
+
+    def setUp(self):
+        super(TestStringFieldThatAcceptsCallable, self).setUp()
+
+        def test_default_function():
+            return "default value"
+
+        self.test_default_function_hash = hashlib.md5(
+            inspect.getsource(test_default_function).encode()).hexdigest()
+        self.field = fields.StringFieldThatAcceptsCallable(
+            default=test_default_function)
+
+    def test_coerce_string(self):
+        self.assertEqual("value", self.field.coerce('obj', 'attr', "value"))
+
+    def test_coerce_function(self):
+        def test_function():
+            return "value"
+        self.assertEqual("value",
+                         self.field.coerce('obj', 'attr', test_function))
+
+    def test_coerce_invalid_type(self):
+        self.assertRaises(ValueError, self.field.coerce,
+                          'obj', 'attr', ('invalid', 'tuple'))
+
+    def test_coerce_function_invalid_type(self):
+        def test_function():
+            return ('invalid', 'tuple',)
+        self.assertRaises(ValueError,
+                          self.field.coerce, 'obj', 'attr', test_function)
+
+    def test_coerce_default_as_function(self):
+        self.assertEqual("default value",
+                         self.field.coerce('obj', 'attr', None))
+
+    def test__repr__includes_default_function_name_and_source_hash(self):
+        expected = ('StringAcceptsCallable(default=test_default_function-%s,'
+                    'nullable=False)' % self.test_default_function_hash)
+        self.assertEqual(expected, repr(self.field))
diff --git a/ironic/tests/unit/objects/test_objects.py b/ironic/tests/unit/objects/test_objects.py
index bd21bd950f..5202d80fe7 100644
--- a/ironic/tests/unit/objects/test_objects.py
+++ b/ironic/tests/unit/objects/test_objects.py
@@ -404,7 +404,7 @@ class TestObject(_LocalTest, _TestObject):
 # version bump. It is md5 hash of object fields and remotable methods.
 # The fingerprint values should only be changed if there is a version bump.
 expected_object_fingerprints = {
-    'Node': '1.18-8cdb6010014b29f17ca636bef72b7800',
+    'Node': '1.18-37a1d39ba8a4957f505dda936ac9146b',
     'MyObj': '1.5-4f5efe8f0fcaf182bbe1c7fe3ba858db',
     'Chassis': '1.3-d656e039fd8ae9f34efc232ab3980905',
     'Port': '1.6-609504503d68982a10f495659990084b',