heat API : Implement API specific exceptions

Implement HeatAPIException and subclasses, which will return error
responses serialized in the correct AWS API format when thrown
ref #125

Change-Id: I9039f181ee64ed59445667f50545dc6481973cb2
Signed-off-by: Steven Hardy <shardy@redhat.com>

heat/api/v1/exception.py

@@ -0,0 +1,192 @@
+# vim: tabstop = 4 shiftwidth=4 softtabstop=4
+
+# Copyright 2010 United States Government as represented by the
+# Administrator of the National Aeronautics and Space Administration.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+"""Heat API exception subclasses - maps API response errors to AWS Errors"""
+
+import webob.exc
+
+
+class HeatAPIException(webob.exc.HTTPError):
+    '''
+    Subclass webob HTTPError so we can correctly serialize the wsgi response
+    into the http response body, using the format specified by the request.
+    Note this should not be used directly, instead use of of the subclasses
+    defined below which map to AWS API errors
+    '''
+    code = 400
+    title = "HeatAPIException"
+    explanation = "Generic HeatAPIException, please use specific subclasses!"
+    err_type = "Sender"
+
+    def get_unserialized_body(self):
+        '''
+        Return a dict suitable for serialization in the wsgi controller
+        This wraps the exception details in a format which maps to the
+        expected format for the AWS API
+        '''
+        # Note the aws response format specifies a "Code" element which is not
+        # the html response code, but the AWS API error code, e.g self.title
+        if self.detail:
+            message = ":".join([self.explanation, self.detail])
+        else:
+            message = self.explanation
+        return {'ErrorResponse': {'Error': {'Type': self.err_type,
+            'Code': self.title, 'Message': message}}}
+
+
+# Common Error Subclasses:
+# As defined in http://docs.amazonwebservices.com/AWSCloudFormation/
+# latest/APIReference/CommonErrors.html
+
+
+class HeatIncompleteSignatureError(HeatAPIException):
+    '''
+    The request signature does not conform to AWS standards
+    '''
+    code = 400
+    title = "IncompleteSignature"
+    explanation = "The request signature does not conform to AWS standards"
+
+
+class HeatInternalFailureError(HeatAPIException):
+    '''
+    The request processing has failed due to some unknown error
+    '''
+    code = 500
+    title = "InternalFailure"
+    explanation = "The request processing has failed due to an internal error"
+    err_type = "Server"
+
+
+class HeatInvalidActionError(HeatAPIException):
+    '''
+    The action or operation requested is invalid
+    '''
+    code = 400
+    title = "InvalidAction"
+    explanation = "The action or operation requested is invalid"
+
+
+class HeatInvalidClientTokenIdError(HeatAPIException):
+    '''
+    The X.509 certificate or AWS Access Key ID provided does not exist
+    '''
+    code = 403
+    title = "InvalidClientTokenId"
+    explanation = "The certificate or AWS Key ID provided does not exist"
+
+
+class HeatInvalidParameterCombinationError(HeatAPIException):
+    '''
+    Parameters that must not be used together were used together
+    '''
+    code = 400
+    title = "InvalidParameterCombination"
+    explanation = "Incompatible parameters were used together"
+
+
+class HeatInvalidParameterValueError(HeatAPIException):
+    '''
+    A bad or out-of-range value was supplied for the input parameter
+    '''
+    code = 400
+    title = "InvalidParameterValue"
+    explanation = "A bad or out-of-range value was supplied"
+
+
+class HeatInvalidQueryParameterError(HeatAPIException):
+    '''
+    AWS query string is malformed, does not adhere to AWS standards
+    '''
+    code = 400
+    title = "InvalidQueryParameter"
+    explanation = "AWS query string is malformed, does not adhere to AWS spec"
+
+
+class HeatMalformedQueryStringError(HeatAPIException):
+    '''
+    The query string is malformed
+    '''
+    code = 404
+    title = "MalformedQueryString"
+    explanation = "The query string is malformed"
+
+
+class HeatMissingActionError(HeatAPIException):
+    '''
+    The request is missing an action or operation parameter
+    '''
+    code = 400
+    title = "MissingAction"
+    explanation = "The request is missing an action or operation parameter"
+
+
+class HeatMissingAuthenticationTokenError(HeatAPIException):
+    '''
+    Request must contain either a valid (registered) AWS Access Key ID
+    or X.509 certificate
+    '''
+    code = 403
+    title = "MissingAuthenticationToken"
+    explanation = "Does not contain a valid AWS Access Key or certificate"
+
+
+class HeatMissingParameterError(HeatAPIException):
+    '''
+    An input parameter that is mandatory for processing the request is missing
+    '''
+    code = 400
+    title = "MissingParameter"
+    explanation = "A mandatory input parameter is missing"
+
+
+class HeatOptInRequiredError(HeatAPIException):
+    '''
+    The AWS Access Key ID needs a subscription for the service
+    '''
+    code = 403
+    title = "OptInRequired"
+    explanation = "The AWS Access Key ID needs a subscription for the service"
+
+
+class HeatRequestExpiredError(HeatAPIException):
+    '''
+    Request is past expires date or the request date (either with 15 minute
+    padding), or the request date occurs more than 15 minutes in the future
+    '''
+    code = 400
+    title = "RequestExpired"
+    explanation = "Request expired or more than 15mins in the future"
+
+
+class HeatServiceUnavailableError(HeatAPIException):
+    '''
+    The request has failed due to a temporary failure of the server
+    '''
+    code = 503
+    title = "ServiceUnavailable"
+    explanation = "Service temporarily unvavailable"
+    err_type = "Server"
+
+
+class HeatThrottlingError(HeatAPIException):
+    '''
+    Request was denied due to request throttling
+    '''
+    code = 400
+    title = "Throttling"
+    explanation = "Request was denied due to request throttling"

heat/api/v1/stacks.py

@@ -62,7 +62,6 @@ class StackController(object):
         '''
             Format response from engine into API format
         '''
-        # TODO : logic to handle error response format will go here..
         return {'%sResponse' % action: {'%sResult' % action: response}}
 
     def list(self, req):

heat/common/wsgi.py

@@ -541,8 +541,20 @@ class Resource(object):
             self.dispatch(serializer, action, response, action_result)
             return response
 
-        # return unserializable result (typically a webob exc)
+        # return unserializable result (typically an exception)
         except Exception:
+            # Here we should get API exceptions derived from HeatAPIException
+            # these implement get_unserialized_body(), which allow us to get
+            # a dict containing the unserialized error response.
+            # If we get something else here (e.g a webob.exc exception),
+            # this will fail, and we just return it without serializing,
+            # which will not conform to the expected AWS error response format
+            try:
+                err_body = action_result.get_unserialized_body()
+                serializer.default(action_result, err_body)
+            except:
+                logging.warning("Unable to serialize exception response")
+
             return action_result
 
     def dispatch(self, obj, action, *args, **kwargs):