Support alternate EC2:ModifyInstanceAttribute request syntax (#4234)

moto/ec2/responses/instances.py

@@ -177,6 +177,7 @@ class InstanceResponse(BaseResponse):
 
     def modify_instance_attribute(self):
         handlers = [
+            self._attribute_value_handler,
             self._dot_value_instance_attribute_handler,
             self._block_device_mapping_handler,
             self._security_grp_instance_attribute_handler,
@@ -258,6 +259,21 @@ class InstanceResponse(BaseResponse):
             )
             return EC2_MODIFY_INSTANCE_ATTRIBUTE
 
+    def _attribute_value_handler(self):
+        attribute_key = self._get_param("Attribute")
+
+        if attribute_key is None:
+            return
+
+        if self.is_not_dryrun("ModifyInstanceAttribute"):
+            value = self._get_param("Value")
+            normalized_attribute = camelcase_to_underscores(attribute_key)
+            instance_id = self._get_param("InstanceId")
+            self.ec2_backend.modify_instance_attribute(
+                instance_id, normalized_attribute, value
+            )
+            return EC2_MODIFY_INSTANCE_ATTRIBUTE
+
     def _security_grp_instance_attribute_handler(self):
         new_security_grp_list = []
         for key, value in self.querystring.items():

tests/test_ec2/test_instances.py

@@ -1775,8 +1775,9 @@ def test_instance_termination_protection():
         r"The instance '{}' may not be terminated.*$".format(instance_id)
     )
 
+    # Use alternate request syntax for setting attribute.
     client.modify_instance_attribute(
-        InstanceId=instance_id, DisableApiTermination={"Value": False}
+        InstanceId=instance_id, Attribute="disableApiTermination", Value="false"
     )
     client.terminate_instances(InstanceIds=[instance_id])