Add private-dns-name filter and fix regional DNS (#1076)

* add private-dns-name to filter_dict_attribute_mapping

* add region_name attribute to Instance and InstanceResponse

* set dns name based on region

* test private-dns-name and network-interface.private-dns-name filters. checking both regional dns formats

* update test_ec2_classic_has_public_ip_address to use correct dns values

moto/ec2/models.py

@@ -366,6 +366,7 @@ class Instance(TaggedEC2Resource, BotoInstance):
         self.user_data = user_data
         self.security_groups = security_groups
         self.instance_type = kwargs.get("instance_type", "m1.small")
+        self.region_name = kwargs.get("region_name", "us-east-1")
         placement = kwargs.get("placement", None)
         self.vpc_id = None
         self.subnet_id = kwargs.get("subnet_id")
@@ -433,7 +434,11 @@ class Instance(TaggedEC2Resource, BotoInstance):
 
     @property
     def private_dns(self):
-        return "ip-{0}.ec2.internal".format(self.private_ip)
+        formatted_ip = self.private_ip.replace('.', '-')
+        if self.region_name == "us-east-1":
+            return "ip-{0}.ec2.internal".format(formatted_ip)
+        else:
+            return "ip-{0}.{1}.compute.internal".format(formatted_ip, self.region_name)
 
     @property
     def public_ip(self):
@@ -442,7 +447,11 @@ class Instance(TaggedEC2Resource, BotoInstance):
     @property
     def public_dns(self):
         if self.public_ip:
-            return "ec2-{0}.compute-1.amazonaws.com".format(self.public_ip)
+            formatted_ip = self.public_ip.replace('.', '-')
+            if self.region_name == "us-east-1":
+                return "ec2-{0}.compute-1.amazonaws.com".format(formatted_ip)
+            else:
+                return "ec2-{0}.{1}.compute.amazonaws.com".format(formatted_ip, self.region_name)
 
     @classmethod
     def create_from_cloudformation_json(cls, resource_name, cloudformation_json, region_name):

moto/ec2/responses/instances.py

@@ -48,11 +48,12 @@ class InstanceResponse(BaseResponse):
             "AssociatePublicIpAddress", [None])[0]
         key_name = self.querystring.get("KeyName", [None])[0]
         tags = self._parse_tag_specification("TagSpecification")
+        region_name = self.region
 
         if self.is_not_dryrun('RunInstance'):
             new_reservation = self.ec2_backend.add_instances(
                 image_id, min_count, user_data, security_group_names,
-                instance_type=instance_type, placement=placement, subnet_id=subnet_id,
+                instance_type=instance_type, placement=placement, region_name=region_name, subnet_id=subnet_id,
                 key_name=key_name, security_group_ids=security_group_ids,
                 nics=nics, private_ip=private_ip, associate_public_ip=associate_public_ip,
                 tags=tags)

moto/ec2/utils.py

@@ -392,7 +392,9 @@ filter_dict_attribute_mapping = {
     'ip-address': 'public_ip',
     'availability-zone': 'placement',
     'architecture': 'architecture',
-    'image-id': 'image_id'
+    'image-id': 'image_id',
+    'network-interface.private-dns-name': 'private_dns',
+    'private-dns-name': 'private_dns'
 }