Add possibility to use any endpoint for dynamodb backend (#4532)

celery/backends/dynamodb.py

@@ -100,6 +100,12 @@ class DynamoDBBackend(KeyValueStoreBackend):
             else:
                 self.aws_region = region
 
+            # If endpoint_url is explicitly set use it instead
+            _get = self.app.conf.get
+            config_endpoint_url = _get('dynamodb_endpoint_url')
+            if config_endpoint_url:
+                self.endpoint_url = config_endpoint_url
+
             self.read_capacity_units = int(
                 query.get(
                     'read',

docs/userguide/configuration.rst

@@ -1245,9 +1245,14 @@ or using the `downloadable version <https://docs.aws.amazon.com/amazondynamodb/l
 of DynamoDB
 `locally <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DynamoDBLocal.Endpoint.html>`_::
 
-    result_backend = 'dynamodb://@localhost:8000
+    result_backend = 'dynamodb://@localhost:8000'
 
-The fields of the URL are defined as follows:
+or using downloadable version or other service with conforming API deployed on any host::
+
+    result_backend = 'dynamodb://@us-east-1'
+    dynamodb_endpoint_url = 'http://192.168.0.40:8000'
+
+The fields of the DynamoDB URL in ``result_backend`` are defined as follows:
 
 #. ``aws_access_key_id & aws_secret_access_key``
 

t/unit/backends/test_dynamodb.py

@@ -38,6 +38,26 @@ class test_DynamoDBBackend:
                 url='dynamodb://a:@'
             )
 
+    def test_get_client_explicit_endpoint(self):
+        table_creation_path = \
+            'celery.backends.dynamodb.DynamoDBBackend._get_or_create_table'
+        with patch('boto3.client') as mock_boto_client, \
+                patch(table_creation_path):
+
+            self.app.conf.dynamodb_endpoint_url = 'http://my.domain.com:666'
+            backend = DynamoDBBackend(
+                app=self.app,
+                url='dynamodb://@us-east-1'
+            )
+            client = backend._get_client()
+            assert backend.client is client
+            mock_boto_client.assert_called_once_with(
+                'dynamodb',
+                endpoint_url='http://my.domain.com:666',
+                region_name='us-east-1'
+            )
+            assert backend.endpoint_url == 'http://my.domain.com:666'
+
     def test_get_client_local(self):
         table_creation_path = \
             'celery.backends.dynamodb.DynamoDBBackend._get_or_create_table'