Fix assigning public ip to instances. Closes #729.

moto/ec2/models.py

@@ -549,6 +549,10 @@ class Instance(BotoInstance, TaggedEC2Resource):
 
             self.attach_eni(use_nic, device_index)
 
+    def set_ip(self, ip_address):
+        # Should we be creating a new ENI?
+        self.nics[0].public_ip = ip_address
+
     def attach_eni(self, eni, device_index):
         device_index = int(device_index)
         self.nics[device_index] = eni
@@ -2663,6 +2667,7 @@ class ElasticAddressBackend(object):
                 eip.eni.public_ip = eip.public_ip
             if eip.domain == "vpc":
                 eip.association_id = random_eip_association_id()
+            instance.set_ip(eip.public_ip)
 
             return eip
 

moto/ec2/responses/instances.py

@@ -207,6 +207,7 @@ EC2_RUN_INSTANCES = """<RunInstancesResponse xmlns="http://ec2.amazonaws.com/doc
           </instanceState>
           <privateDnsName>{{ instance.private_dns }}</privateDnsName>
           <publicDnsName>{{ instance.public_dns }}</publicDnsName>
+          <dnsName>{{ instance.public_dns }}</dnsName>
           <reason/>
           <keyName>{{ instance.key_name }}</keyName>
           <amiLaunchIndex>0</amiLaunchIndex>
@@ -335,6 +336,7 @@ EC2_DESCRIBE_INSTANCES = """<DescribeInstancesResponse xmlns="http://ec2.amazona
                     </instanceState>
                     <privateDnsName>{{ instance.private_dns }}</privateDnsName>
                     <publicDnsName>{{ instance.public_dns }}</publicDnsName>
+                    <dnsName>{{ instance.public_dns }}</dnsName>
                     <reason>{{ instance._reason }}</reason>
                     <keyName>{{ instance.key_name }}</keyName>
                     <amiLaunchIndex>0</amiLaunchIndex>