Add support for excluding specific exceptions from retry

awsretry/__init__.py

@@ -47,7 +47,7 @@ def found(response_code):
         pass
 
     @classmethod
-    def backoff(cls, tries=10, delay=3, backoff=1.1, added_exceptions=list()):
+    def backoff(cls, tries=10, delay=3, backoff=1.1, added_exceptions=list(), excluded_exceptions=list()):
         """ Retry calling the Cloud decorated function using an exponential
             backoff.
         Kwargs:
@@ -60,6 +60,8 @@ def backoff(cls, tries=10, delay=3, backoff=1.1, added_exceptions=list()):
                 default=2
             added_exceptions (list): Other exceptions to retry on.
                 default=[]
+            excluded_exceptions (list): Exceptions not to retry on.
+                default=[]
 
         """
         def deco(f):
@@ -73,7 +75,7 @@ def retry_func(*args, **kwargs):
                         base_exception_class = cls.base_class(e)
                         if isinstance(e, base_exception_class):
                             response_code = cls.status_code_from_exception(e)
-                            if cls.found(response_code, added_exceptions):
+                            if cls.found(response_code, added_exceptions, excluded_exceptions):
                                 logging.info("{0}: Retrying in {1} seconds...".format(str(e), max_delay))
                                 time.sleep(max_delay)
                                 max_tries -= 1
@@ -119,7 +121,11 @@ def status_code_from_exception(error):
         return error.__class__.__name__
 
     @staticmethod
-    def found(response_code, added_exceptions):
+    def found(response_code, added_exceptions, excluded_exceptions):
+        # If the response_code is in the excluded list return immediately
+        if response_code in excluded_exceptions:
+            return False
+
         # This list of failures is based on this API Reference
         # http://docs.aws.amazon.com/AWSEC2/latest/APIReference/errors-overview.html
         retry_on = [

tests/test_awsretry.py

@@ -62,6 +62,48 @@ def raise_unexpected_error():
 
         self.assertEqual(self.counter, 1)
 
+    def test_excluded_exception_does_not_retry(self):
+        self.counter = 0
+        err_msg = {'Error': {'Code': 'ResourceNotFoundException'}}
+
+        @AWSRetry.backoff(tries=4, delay=0.1, excluded_exceptions=['ResourceNotFoundException'])
+        def raise_excluded_error():
+            self.counter += 1
+            raise botocore.exceptions.ClientError(err_msg, 'excluded')
+
+        with self.assertRaises(botocore.exceptions.ClientError):
+            raise_excluded_error()
+
+        self.assertEqual(self.counter, 1)
+
+    def test_excluded_exception_retry_for_non_match(self):
+        self.counter = 0
+        err_msg = {'Error': {'Code': 'InstanceId.NotFound'}}
+
+        @AWSRetry.backoff(tries=4, delay=0.1, excluded_exceptions=['ResourceNotFoundException'])
+        def raise_excluded_error_no_match():
+            self.counter += 1
+            raise botocore.exceptions.ClientError(err_msg, 'excluded_not_match')
+
+        with self.assertRaises(botocore.exceptions.ClientError):
+            raise_excluded_error_no_match()
+
+        self.assertEqual(self.counter, 4)
+
+    def test_excluded_core_exception_does_not_retry(self):
+        self.counter = 0
+        err_msg = {'Error': {'Code': 'InternalFailure'}}
+
+        @AWSRetry.backoff(tries=4, delay=0.1, excluded_exceptions=['InternalFailure'])
+        def raise_excluded_core_error():
+            self.counter += 1
+            raise botocore.exceptions.ClientError(err_msg, 'excluded_core')
+
+        with self.assertRaises(botocore.exceptions.ClientError):
+            raise_excluded_core_error()
+
+        self.assertEqual(self.counter, 1)
+
 
 if __name__ == '__main__':
     unittest.main()