Module aws_lambda_powertools.utilities.idempotency.idempotency

Primary interface for idempotent Lambda functions utility

Functions

def idempotent(handler: Callable[[Any, LambdaContext], Any], event: dict[str, Any], context: LambdaContext, persistence_store: BasePersistenceLayer, config: IdempotencyConfig | None = None, **kwargs)

Decorator to handle idempotency

Parameters

handler : Callable

Lambda's handler

event : dict

Lambda's Event

context : dict

Lambda's Context

persistence_store : BasePersistenceLayer

Instance of BasePersistenceLayer to store data

config : IdempotencyConfig

Configuration

Examples

Processes Lambda's event in an idempotent manner

>>> from aws_lambda_powertools.utilities.idempotency import (
>>>    idempotent, DynamoDBPersistenceLayer, IdempotencyConfig
>>> )
>>>
>>> idem_config=IdempotencyConfig(event_key_jmespath="body")
>>> persistence_layer = DynamoDBPersistenceLayer(table_name="idempotency_store")
>>>
>>> @idempotent(config=idem_config, persistence_store=persistence_layer)
>>> def handler(event, context):
>>>     return {"StatusCode": 200}

def idempotent_function(function: AnyCallableT | None = None, *, data_keyword_argument: str, persistence_store: BasePersistenceLayer, config: IdempotencyConfig | None = None, output_serializer: BaseIdempotencySerializer | type[BaseIdempotencyModelSerializer] | None = None, **kwargs: Any)

Decorator to handle idempotency of any function

Parameters

function : Callable

Function to be decorated

data_keyword_argument : str

Keyword parameter name in function's signature that we should hash as idempotency key, e.g. "order"

persistence_store : BasePersistenceLayer

Instance of BasePersistenceLayer to store data

config : IdempotencyConfig

Configuration

output_serializer : BaseIdempotencySerializer | type[BaseIdempotencyModelSerializer] | None

Serializer to transform the data to and from a dictionary. If not supplied, no serialization is done via the NoOpSerializer. In case a serializer of type inheriting BaseIdempotencyModelSerializer is given, the serializer is derived from the function return type.

Examples

Processes an order in an idempotent manner

from aws_lambda_powertools.utilities.idempotency import (
   idempotent_function, DynamoDBPersistenceLayer, IdempotencyConfig
)

idem_config=IdempotencyConfig(event_key_jmespath="order_id")
persistence_layer = DynamoDBPersistenceLayer(table_name="idempotency_store")

@idempotent_function(data_keyword_argument="order", config=idem_config, persistence_store=persistence_layer)
def process_order(customer_id: str, order: dict, **kwargs):
    return {"StatusCode": 200}