tweak Fn::GetAtt to return resource_json if resource is not implemented. DRY

This is better than failing out with a misleading Boto 400 error which should only happen when get_cfn_attribute is called but fails.

moto/cloudformation/exceptions.py

@@ -0,0 +1,6 @@
+from __future__ import unicode_literals
+
+
+class UnformattedGetAttTemplateException(Exception):
+    description = 'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt'
+    status_code = 400

moto/cloudformation/parsing.py

@@ -8,6 +8,7 @@ from moto.elb import models as elb_models
 from moto.iam import models as iam_models
 from moto.sqs import models as sqs_models
 from .utils import random_suffix
+from .exceptions import UnformattedGetAttTemplateException
 from boto.cloudformation.stack import Output
 from boto.exception import BotoServerError
 
@@ -72,17 +73,22 @@ def clean_json(resource_json, resources_map):
                 return resource
 
         if 'Fn::GetAtt' in resource_json:
+
             resource = resources_map[resource_json['Fn::GetAtt'][0]]
+            if resource is None:
+                return resource_json
             try:
                 return resource.get_cfn_attribute(resource_json['Fn::GetAtt'][1])
             except NotImplementedError as n:
-                raise NotImplementedError(n.message.format(resource_json['Fn::GetAtt'][0]))
+                logger.warning(n.message.format(resource_json['Fn::GetAtt'][0]))
-            except AttributeError:
+            except UnformattedGetAttTemplateException:
                 raise BotoServerError(
-                    400,
+                    UnformattedGetAttTemplateException.status_code,
                     'Bad Request',
-                    'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt'.format(
+                    UnformattedGetAttTemplateException.description.format(
-                    resource_json['Fn::GetAtt'][0], resource_json['Fn::GetAtt'][1]))
+                        resource_json['Fn::GetAtt'][0], resource_json['Fn::GetAtt'][1]))
+            except Exception as e:
+                pass
 
         cleaned_json = {}
         for key, value in resource_json.items():

moto/ec2/models.py

@@ -9,7 +9,6 @@ from boto.ec2.instance import Instance as BotoInstance, Reservation
 from boto.ec2.blockdevicemapping import BlockDeviceMapping, BlockDeviceType
 from boto.ec2.spotinstancerequest import SpotInstanceRequest as BotoSpotRequest
 from boto.ec2.launchspecification import LaunchSpecification
-from boto.exception import BotoServerError
 
 from moto.core import BaseBackend
 from moto.core.models import Model
@@ -187,13 +186,12 @@ class NetworkInterface(object):
             return self._group_set
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'PrimaryPrivateIpAddress':
             return self.private_ip_address
         elif attribute_name == 'SecondaryPrivateIpAddresses':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "SecondaryPrivateIpAddresses" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class NetworkInterfaceBackend(object):
@@ -423,6 +421,7 @@ class Instance(BotoInstance, TaggedEC2Resource):
         eni.device_index = None
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'AvailabilityZone':
             return self.placement
         elif attribute_name == 'PrivateDnsName':
@@ -433,9 +432,7 @@ class Instance(BotoInstance, TaggedEC2Resource):
             return self.private_ip_address
         elif attribute_name == 'PublicIp':
             return self.ip_address
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class InstanceBackend(object):
@@ -997,11 +994,10 @@ class SecurityGroup(object):
         return True
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'GroupId':
             return self.id
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class SecurityGroupBackend(object):
@@ -1527,11 +1523,10 @@ class Subnet(TaggedEC2Resource):
         return filter_value
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'AvailabilityZone':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "AvailabilityZone" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class SubnetBackend(object):
@@ -1969,11 +1964,10 @@ class ElasticAddress(object):
         return self.allocation_id
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'AllocationId':
             return self.allocation_id
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class ElasticAddressBackend(object):

moto/elb/models.py

@@ -1,6 +1,5 @@
 from __future__ import unicode_literals
 from moto.core import BaseBackend
-from boto.exception import BotoServerError
 
 
 class FakeHealthCheck(object):
@@ -58,6 +57,7 @@ class FakeLoadBalancer(object):
         return self.name
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'CanonicalHostedZoneName':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "CanonicalHostedZoneName" ]"')
         elif attribute_name == 'CanonicalHostedZoneNameID':
@@ -68,9 +68,7 @@ class FakeLoadBalancer(object):
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "SourceSecurityGroup.GroupName" ]"')
         elif attribute_name == 'SourceSecurityGroup.OwnerAlias':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "SourceSecurityGroup.OwnerAlias" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class ELBBackend(BaseBackend):

moto/iam/models.py

@@ -31,11 +31,10 @@ class Role(object):
         return self.id
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'Arn':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "Arn" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class InstanceProfile(object):
@@ -61,11 +60,10 @@ class InstanceProfile(object):
         return self.name
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'Arn':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "Arn" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class Certificate(object):
@@ -93,11 +91,10 @@ class AccessKey(object):
         )
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'SecretAccessKey':
             return self.secret_access_key
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class Group(object):
@@ -113,11 +110,10 @@ class Group(object):
         self.users = []
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'Arn':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "Arn" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class User(object):
@@ -172,11 +168,10 @@ class User(object):
             raise BotoServerError(404, 'Not Found')
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'Arn':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "Arn" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class IAMBackend(BaseBackend):

moto/s3/models.py

@@ -12,7 +12,6 @@ from moto.core import BaseBackend
 from moto.core.utils import iso_8601_datetime, rfc_1123_datetime
 from .exceptions import BucketAlreadyExists, MissingBucket
 from .utils import clean_key_name, _VersionedKeyStore
-from boto.exception import BotoServerError
 
 UPLOAD_ID_BYTES = 43
 UPLOAD_PART_MIN_SIZE = 5242880
@@ -172,13 +171,12 @@ class FakeBucket(object):
         return self.versioning_status == 'Enabled'
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'DomainName':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "DomainName" ]"')
         elif attribute_name == 'WebsiteURL':
             raise NotImplementedError('"Fn::GetAtt" : [ "{0}" , "WebsiteURL" ]"')
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class S3Backend(BaseBackend):

moto/sns/models.py

@@ -8,7 +8,6 @@ from moto.core import BaseBackend
 from moto.core.utils import iso_8601_datetime
 from moto.sqs.models import sqs_backend
 from .utils import make_arn_for_topic, make_arn_for_subscription
-from boto.exception import BotoServerError
 
 DEFAULT_ACCOUNT_ID = 123456789012
 
@@ -35,11 +34,10 @@ class Topic(object):
         return message_id
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'TopicName':
             return self.name
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class Subscription(object):

moto/sqs/models.py

@@ -4,7 +4,7 @@ import hashlib
 import time
 import re
 
-from boto.exception import BotoServerError
+
 from moto.core import BaseBackend
 from moto.core.utils import camelcase_to_underscores, get_random_message_id
 from .utils import generate_receipt_handle, unix_time_millis
@@ -154,13 +154,12 @@ class Queue(object):
         self._messages.append(message)
 
     def get_cfn_attribute(self, attribute_name):
+        from moto.cloudformation.exceptions import UnformattedGetAttTemplateException
         if attribute_name == 'Arn':
             return self.queue_arn
         elif attribute_name == 'QueueName':
             return self.name
-        raise BotoServerError(400,
+        raise UnformattedGetAttTemplateException()
-                              'Bad Request',
-                              'Template error: resource {0} does not support attribute type {1} in Fn::GetAtt')
 
 
 class SQSBackend(BaseBackend):