refactor(idempotent): Create a config class

Author: Michael Brewer

aws_lambda_powertools/utilities/idempotency/config.py

@@ -0,0 +1,38 @@
+class IdempotencyConfig:
+    def __init__(
+        self,
+        event_key_jmespath: str = "",
+        payload_validation_jmespath: str = "",
+        raise_on_no_idempotency_key: bool = False,
+        expires_after_seconds: int = 60 * 60,  # 1 hour default
+        use_local_cache: bool = False,
+        local_cache_max_items: int = 256,
+        hash_function: str = "md5",
+    ):
+        """
+        Initialize the base persistence layer
+
+        Parameters
+        ----------
+        event_key_jmespath: str
+            A jmespath expression to extract the idempotency key from the event record
+        payload_validation_jmespath: str
+            A jmespath expression to extract the payload to be validated from the event record
+        raise_on_no_idempotency_key: bool, optional
+            Raise exception if no idempotency key was found in the request, by default False
+        expires_after_seconds: int
+            The number of seconds to wait before a record is expired
+        use_local_cache: bool, optional
+            Whether to locally cache idempotency results, by default False
+        local_cache_max_items: int, optional
+            Max number of items to store in local cache, by default 1024
+        hash_function: str, optional
+            Function to use for calculating hashes, by default md5.
+        """
+        self.event_key_jmespath = event_key_jmespath
+        self.payload_validation_jmespath = payload_validation_jmespath
+        self.raise_on_no_idempotency_key = raise_on_no_idempotency_key
+        self.expires_after_seconds = expires_after_seconds
+        self.use_local_cache = use_local_cache
+        self.local_cache_max_items = local_cache_max_items
+        self.hash_function = hash_function

aws_lambda_powertools/utilities/idempotency/idempotency.py

@@ -5,6 +5,7 @@
 from typing import Any, Callable, Dict, Optional
 
 from aws_lambda_powertools.middleware_factory import lambda_handler_decorator
+from aws_lambda_powertools.utilities.idempotency.config import IdempotencyConfig
 from aws_lambda_powertools.utilities.idempotency.exceptions import (
     IdempotencyAlreadyInProgressError,
     IdempotencyInconsistentStateError,
@@ -29,6 +30,7 @@ def idempotent(
     event: Dict[str, Any],
     context: LambdaContext,
     persistence_store: BasePersistenceLayer,
+    config: IdempotencyConfig = None,
 ) -> Any:
     """
     Middleware to handle idempotency
@@ -43,20 +45,24 @@ def idempotent(
         Lambda's Context
     persistence_store: BasePersistenceLayer
         Instance of BasePersistenceLayer to store data
+    config: IdempotencyConfig
+        Configutation
 
     Examples
     --------
     **Processes Lambda's event in an idempotent manner**
-        >>> from aws_lambda_powertools.utilities.idempotency import idempotent, DynamoDBPersistenceLayer
+        >>> from aws_lambda_powertools.utilities.idempotency import (
+        >>>    idempotent, DynamoDBPersistenceLayer
+        >>> )
         >>>
-        >>> persistence_store = DynamoDBPersistenceLayer(event_key_jmespath="body", table_name="idempotency_store")
+        >>> persistence_layer = DynamoDBPersistenceLayer(table_name="idempotency_store")
         >>>
-        >>> @idempotent(persistence_store=persistence_store)
+        >>> @idempotent(persistence_store=persistence_layer, config=IdempotencyConfig(event_key_jmespath="body"))
         >>> def handler(event, context):
         >>>     return {"StatusCode": 200}
     """
 
-    idempotency_handler = IdempotencyHandler(handler, event, context, persistence_store)
+    idempotency_handler = IdempotencyHandler(handler, event, context, config, persistence_store)
 
     # IdempotencyInconsistentStateError can happen under rare but expected cases when persistent state changes in the
     # small time between put & get requests. In most cases we can retry successfully on this exception.
@@ -82,6 +88,7 @@ def __init__(
         lambda_handler: Callable[[Any, LambdaContext], Any],
         event: Dict[str, Any],
         context: LambdaContext,
+        config: IdempotencyConfig,
         persistence_store: BasePersistenceLayer,
     ):
         """
@@ -98,6 +105,7 @@ def __init__(
         persistence_store : BasePersistenceLayer
             Instance of persistence layer to store idempotency records
         """
+        persistence_store.configure(config)
         self.persistence_store = persistence_store
         self.context = context
         self.event = event

aws_lambda_powertools/utilities/idempotency/persistence/base.py

@@ -21,6 +21,7 @@
     IdempotencyKeyError,
     IdempotencyValidationError,
 )
+from aws_lambda_powertools.utilities.idempotency.idempotency import IdempotencyConfig
 
 logger = logging.getLogger(__name__)
 
@@ -106,49 +107,39 @@ class BasePersistenceLayer(ABC):
     Abstract Base Class for Idempotency persistence layer.
     """
 
-    def __init__(
-        self,
-        event_key_jmespath: str = "",
-        payload_validation_jmespath: str = "",
-        expires_after_seconds: int = 60 * 60,  # 1 hour default
-        use_local_cache: bool = False,
-        local_cache_max_items: int = 256,
-        hash_function: str = "md5",
-        raise_on_no_idempotency_key: bool = False,
-    ) -> None:
+    def __init__(self):
+        self.event_key_jmespath = None
+        self.event_key_compiled_jmespath = None
+        self.payload_validation_enabled = None
+        self.validation_key_jmespath = None
+        self.raise_on_no_idempotency_key = None
+        self.expires_after_seconds = None
+        self.use_local_cache = None
+        self._cache = None
+        self.hash_function = None
+
+    def configure(self, config: IdempotencyConfig,) -> None:
         """
         Initialize the base persistence layer
 
         Parameters
         ----------
-        event_key_jmespath: str
-            A jmespath expression to extract the idempotency key from the event record
-        payload_validation_jmespath: str
-            A jmespath expression to extract the payload to be validated from the event record
-        expires_after_seconds: int
-            The number of seconds to wait before a record is expired
-        use_local_cache: bool, optional
-            Whether to locally cache idempotency results, by default False
-        local_cache_max_items: int, optional
-            Max number of items to store in local cache, by default 1024
-        hash_function: str, optional
-            Function to use for calculating hashes, by default md5.
-        raise_on_no_idempotency_key: bool, optional
-            Raise exception if no idempotency key was found in the request, by default False
-        """
-        self.event_key_jmespath = event_key_jmespath
+        config: IdempotencyConfig
+            Configuration settings
+        """
+        self.event_key_jmespath = config.event_key_jmespath
         if self.event_key_jmespath:
-            self.event_key_compiled_jmespath = jmespath.compile(event_key_jmespath)
-        self.expires_after_seconds = expires_after_seconds
-        self.use_local_cache = use_local_cache
-        if self.use_local_cache:
-            self._cache = LRUDict(max_items=local_cache_max_items)
+            self.event_key_compiled_jmespath = jmespath.compile(config.event_key_jmespath)
         self.payload_validation_enabled = False
-        if payload_validation_jmespath:
-            self.validation_key_jmespath = jmespath.compile(payload_validation_jmespath)
+        if config.payload_validation_jmespath:
+            self.validation_key_jmespath = jmespath.compile(config.payload_validation_jmespath)
             self.payload_validation_enabled = True
-        self.hash_function = getattr(hashlib, hash_function)
-        self.raise_on_no_idempotency_key = raise_on_no_idempotency_key
+        self.raise_on_no_idempotency_key = config.raise_on_no_idempotency_key
+        self.expires_after_seconds = config.expires_after_seconds
+        self.use_local_cache = config.use_local_cache
+        if self.use_local_cache:
+            self._cache = LRUDict(max_items=config.local_cache_max_items)
+        self.hash_function = getattr(hashlib, config.hash_function)
 
     def _get_hashed_idempotency_key(self, lambda_event: Dict[str, Any]) -> str:
         """

aws_lambda_powertools/utilities/idempotency/persistence/dynamodb.py

@@ -26,8 +26,6 @@ def __init__(
         validation_key_attr: str = "validation",
         boto_config: Optional[Config] = None,
         boto3_session: Optional[boto3.session.Session] = None,
-        *args,
-        **kwargs,
     ):
         """
         Initialize the DynamoDB client
@@ -57,9 +55,9 @@ def __init__(
         **Create a DynamoDB persistence layer with custom settings**
             >>> from aws_lambda_powertools.utilities.idempotency import idempotent, DynamoDBPersistenceLayer
             >>>
-            >>> persistence_store = DynamoDBPersistenceLayer(event_key="body", table_name="idempotency_store")
+            >>> persistence_store = DynamoDBPersistenceLayer(table_name="idempotency_store")
             >>>
-            >>> @idempotent(persistence_store=persistence_store)
+            >>> @idempotent(persistence_store=persistence_store, event_key="body")
             >>> def handler(event, context):
             >>>     return {"StatusCode": 200}
         """
@@ -74,7 +72,7 @@ def __init__(
         self.status_attr = status_attr
         self.data_attr = data_attr
         self.validation_key_attr = validation_key_attr
-        super(DynamoDBPersistenceLayer, self).__init__(*args, **kwargs)
+        super(DynamoDBPersistenceLayer, self).__init__()
 
     def _item_to_data_record(self, item: Dict[str, Any]) -> DataRecord:
         """

tests/functional/idempotency/conftest.py

@@ -12,6 +12,7 @@
 
 from aws_lambda_powertools.shared.json_encoder import Encoder
 from aws_lambda_powertools.utilities.idempotency import DynamoDBPersistenceLayer
+from aws_lambda_powertools.utilities.idempotency.idempotency import IdempotencyConfig
 from aws_lambda_powertools.utilities.validation import envelopes
 from aws_lambda_powertools.utilities.validation.base import unwrap_event_from_envelope
 
@@ -150,34 +151,30 @@ def hashed_validation_key(lambda_apigw_event):
 
 
 @pytest.fixture
-def persistence_store(config, request, default_jmespath):
-    persistence_store = DynamoDBPersistenceLayer(
+def persistence_store(config):
+    return DynamoDBPersistenceLayer(table_name=TABLE_NAME, boto_config=config,)
+
+
+@pytest.fixture
+def idempotency_config(config, request, default_jmespath):
+    return IdempotencyConfig(
         event_key_jmespath=request.param.get("event_key_jmespath") or default_jmespath,
-        table_name=TABLE_NAME,
-        boto_config=config,
         use_local_cache=request.param["use_local_cache"],
     )
-    return persistence_store
 
 
 @pytest.fixture
-def persistence_store_without_jmespath(config, request):
-    persistence_store = DynamoDBPersistenceLayer(
-        table_name=TABLE_NAME, boto_config=config, use_local_cache=request.param["use_local_cache"],
-    )
-    return persistence_store
+def config_without_jmespath(config, request):
+    return IdempotencyConfig(use_local_cache=request.param["use_local_cache"],)
 
 
 @pytest.fixture
-def persistence_store_with_validation(config, request, default_jmespath):
-    persistence_store = DynamoDBPersistenceLayer(
+def config_with_validation(config, request, default_jmespath):
+    return IdempotencyConfig(
         event_key_jmespath=default_jmespath,
-        table_name=TABLE_NAME,
-        boto_config=config,
         use_local_cache=request.param,
         payload_validation_jmespath="requestContext",
     )
-    return persistence_store
 
 
 @pytest.fixture