Add ClientError getters for code, message, http_headers, http_status_…

…code, and request_id

This change adds the following properties to the ClientError class. These properties will make it easier to
work with the error object and extract information from it.

- code: The error code returned by the service.
- message: The error message returned by the service.
- http_headers: The HTTP headers returned by the service.
- http_status_code: The HTTP status code returned by the service.
- request_id: The request ID returned by the service.

botocore/exceptions.py

@@ -553,6 +553,31 @@ def __reduce__(self):
         # module. So at the very least return a ClientError back.
         return ClientError, (self.response, self.operation_name)
 
+    @property
+    def code(self):
+        """The error code returned by the AWS service."""
+        return self.response.get('Error', {}).get('Code', 'Unknown')
+
+    @property
+    def message(self):
+        """The error message returned by the AWS service."""
+        return self.response.get('Error', {}).get('Message', 'Unknown')
+
+    @property
+    def request_id(self):
+        """The request ID returned by the AWS service."""
+        return self.response.get('ResponseMetadata').get('RequestId')
+
+    @property
+    def http_status_code(self):
+        """The HTTP status code returned by the AWS service."""
+        return self.response.get('ResponseMetadata', {}).get('HTTPStatusCode')
+
+    @property
+    def http_headers(self):
+        """The HTTP headers returned by the AWS service."""
+        return self.response.get('ResponseMetadata', {}).get('HTTPHeaders', {})
+
 
 class EventStreamError(ClientError):
     pass

tests/unit/test_exceptions.py

@@ -23,6 +23,17 @@ def test_client_error_can_handle_missing_code_or_message():
     response = {'Error': {}}
     expect = 'An error occurred (Unknown) when calling the blackhole operation: Unknown'
     assert str(exceptions.ClientError(response, 'blackhole')) == expect
+    assert exceptions.ClientError.code == 'Unknown'
+    assert exceptions.ClientError.message == 'Unknown'
+
+
+def test_client_error_can_handle_missing_response_metadata():
+    response = {'Error': {}}
+    assert (
+        exceptions.ClientError(response, 'blackhole').http_status_code is None
+    )
+    assert exceptions.ClientError(response, 'blackhole').request_id is None
+    assert exceptions.ClientError(response, 'blackhole').http_headers == {}
 
 
 def test_client_error_has_operation_name_set():