Module aws_lambda_powertools.utilities.batch

Batch processing utility

Sub-modules

aws_lambda_powertools.utilities.batch.base

Batch processing utilities

aws_lambda_powertools.utilities.batch.decorators

aws_lambda_powertools.utilities.batch.exceptions

Batch processing exceptions

aws_lambda_powertools.utilities.batch.sqs_fifo_partial_processor

aws_lambda_powertools.utilities.batch.types

Functions

def async_batch_processor(handler: Callable, event: Dict, context: LambdaContext, record_handler: Callable[..., Awaitable[Any]], processor: AsyncBatchProcessor)

Middleware to handle batch event processing

Notes

Consider using async_process_partial_response function for an easier experience.

Parameters

handler : Callable

Lambda's handler

event : Dict

Lambda's Event

context : LambdaContext

Lambda's Context

record_handler : Callable[…, Awaitable[Any]]

Callable to process each record from the batch

processor : AsyncBatchProcessor

Batch Processor to handle partial failure cases

Examples

Processes Lambda's event with a BasePartialProcessor >>> from aws_lambda_powertools.utilities.batch import async_batch_processor, AsyncBatchProcessor >>> from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord >>> >>> processor = AsyncBatchProcessor(event_type=EventType.SQS) >>> >>> async def async_record_handler(record: SQSRecord): >>> payload: str = record.body >>> return payload >>> >>> @async_batch_processor(record_handler=async_record_handler, processor=processor) >>> def lambda_handler(event, context): >>> return processor.response()

Limitations

• Sync batch processors. Use batch_processor() instead.

def async_process_partial_response(event: Dict, record_handler: Callable, processor: AsyncBatchProcessor, context: LambdaContext | None = None) ‑> PartialItemFailureResponse

Higher level function to handle batch event processing asynchronously.

Parameters

event : Dict

Lambda's original event

record_handler : Callable

Callable to process each record from the batch

processor : AsyncBatchProcessor

Batch Processor to handle partial failure cases

context : LambdaContext

Lambda's context, used to optionally inject in record handler

Returns

result : PartialItemFailureResponse

Lambda Partial Batch Response

Examples

Processes Lambda's SQS event

from aws_lambda_powertools.utilities.batch import AsyncBatchProcessor, EventType, process_partial_response
from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord

processor = BatchProcessor(EventType.SQS)

async def record_handler(record: SQSRecord):
    return record.body

def handler(event, context):
    return async_process_partial_response(
        event=event, record_handler=record_handler, processor=processor, context=context
    )

Limitations

• Sync batch processors. Use process_partial_response() instead.

def batch_processor(handler: Callable, event: Dict, context: LambdaContext, record_handler: Callable, processor: BatchProcessor)

Middleware to handle batch event processing

Notes

Consider using process_partial_response function for an easier experience.

Parameters

handler : Callable

Lambda's handler

event : Dict

Lambda's Event

context : LambdaContext

Lambda's Context

record_handler : Callable

Callable or corutine to process each record from the batch

processor : BatchProcessor

Batch Processor to handle partial failure cases

Examples

Processes Lambda's event with a BatchProcessor

>>> from aws_lambda_powertools.utilities.batch import batch_processor, BatchProcessor, EventType
>>> from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
>>>
>>> processor = BatchProcessor(EventType.SQS)
>>>
>>> def record_handler(record):
>>>     return record["body"]
>>>
>>> @batch_processor(record_handler=record_handler, processor=BatchProcessor())
>>> def handler(event, context):
>>>     return processor.response()

Limitations

• Async batch processors. Use async_batch_processor() instead.

def process_partial_response(event: Dict, record_handler: Callable, processor: BasePartialBatchProcessor, context: LambdaContext | None = None) ‑> PartialItemFailureResponse

Higher level function to handle batch event processing.

Parameters

event : Dict

Lambda's original event

record_handler : Callable

Callable to process each record from the batch

processor : BasePartialBatchProcessor

Batch Processor to handle partial failure cases

context : LambdaContext

Lambda's context, used to optionally inject in record handler

Returns

result : PartialItemFailureResponse

Lambda Partial Batch Response

Examples

Processes Lambda's SQS event

from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, process_partial_response
from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord

processor = BatchProcessor(EventType.SQS)

def record_handler(record: SQSRecord):
    return record.body

def handler(event, context):
    return process_partial_response(
        event=event, record_handler=record_handler, processor=processor, context=context
    )

Limitations

• Async batch processors. Use async_process_partial_response() instead.

Classes

class AsyncBatchProcessor (event_type: EventType, model: Optional[ForwardRef('BatchTypeModels')] = None)

Process native partial responses from SQS, Kinesis Data Streams, and DynamoDB asynchronously.

Example

Process batch triggered by SQS

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = BatchProcessor(event_type=EventType.SQS)
tracer = Tracer()
logger = Logger()


@tracer.capture_method
async def record_handler(record: SQSRecord):
    payload: str = record.body
    if payload:
        item: dict = json.loads(payload)
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
@batch_processor(record_handler=record_handler, processor=processor)
def lambda_handler(event, context: LambdaContext):
    return processor.response()

Process batch triggered by Kinesis Data Streams

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.kinesis_stream_event import KinesisStreamRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = BatchProcessor(event_type=EventType.KinesisDataStreams)
tracer = Tracer()
logger = Logger()


@tracer.capture_method
async def record_handler(record: KinesisStreamRecord):
    logger.info(record.kinesis.data_as_text)
    payload: dict = record.kinesis.data_as_json()
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
@batch_processor(record_handler=record_handler, processor=processor)
def lambda_handler(event, context: LambdaContext):
    return processor.response()

Process batch triggered by DynamoDB Data Streams

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.dynamo_db_stream_event import DynamoDBRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = BatchProcessor(event_type=EventType.DynamoDBStreams)
tracer = Tracer()
logger = Logger()


@tracer.capture_method
async def record_handler(record: DynamoDBRecord):
    logger.info(record.dynamodb.new_image)
    payload: dict = json.loads(record.dynamodb.new_image.get("item"))
    # alternatively:
    # changes: Dict[str, Any] = record.dynamodb.new_image  # noqa: ERA001
    # payload = change.get("Message") -> "<payload>"
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
def lambda_handler(event, context: LambdaContext):
    batch = event["Records"]
    with processor(records=batch, processor=processor):
        processed_messages = processor.process() # kick off processing, return list[tuple]

    return processor.response()

Raises

BatchProcessingError

When all batch records fail processing

Limitations

• Sync record handler not supported, use BatchProcessor instead.

Process batch and partially report failed items

Parameters

event_type : EventType

Whether this is a SQS, DynamoDB Streams, or Kinesis Data Stream event

model : Optional["BatchTypeModels"]

Parser's data model using either SqsRecordModel, DynamoDBStreamRecordModel, KinesisDataStreamRecord

Exceptions

BatchProcessingError Raised when the entire batch has failed processing

Expand source code

class AsyncBatchProcessor(BasePartialBatchProcessor):
    """Process native partial responses from SQS, Kinesis Data Streams, and DynamoDB asynchronously.

    Example
    -------

    ## Process batch triggered by SQS

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = BatchProcessor(event_type=EventType.SQS)
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    async def record_handler(record: SQSRecord):
        payload: str = record.body
        if payload:
            item: dict = json.loads(payload)
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    @batch_processor(record_handler=record_handler, processor=processor)
    def lambda_handler(event, context: LambdaContext):
        return processor.response()
    ```

    ## Process batch triggered by Kinesis Data Streams

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.kinesis_stream_event import KinesisStreamRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = BatchProcessor(event_type=EventType.KinesisDataStreams)
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    async def record_handler(record: KinesisStreamRecord):
        logger.info(record.kinesis.data_as_text)
        payload: dict = record.kinesis.data_as_json()
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    @batch_processor(record_handler=record_handler, processor=processor)
    def lambda_handler(event, context: LambdaContext):
        return processor.response()
    ```

    ## Process batch triggered by DynamoDB Data Streams

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.dynamo_db_stream_event import DynamoDBRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = BatchProcessor(event_type=EventType.DynamoDBStreams)
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    async def record_handler(record: DynamoDBRecord):
        logger.info(record.dynamodb.new_image)
        payload: dict = json.loads(record.dynamodb.new_image.get("item"))
        # alternatively:
        # changes: Dict[str, Any] = record.dynamodb.new_image  # noqa: ERA001
        # payload = change.get("Message") -> "<payload>"
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    def lambda_handler(event, context: LambdaContext):
        batch = event["Records"]
        with processor(records=batch, processor=processor):
            processed_messages = processor.process() # kick off processing, return list[tuple]

        return processor.response()
    ```


    Raises
    ------
    BatchProcessingError
        When all batch records fail processing

    Limitations
    -----------
    * Sync record handler not supported, use BatchProcessor instead.
    """

    def _process_record(self, record: dict):
        raise NotImplementedError()

    async def _async_process_record(self, record: dict) -> Union[SuccessResponse, FailureResponse]:
        """
        Process a record with instance's handler

        Parameters
        ----------
        record: dict
            A batch record to be processed.
        """
        data: Optional["BatchTypeModels"] = None
        try:
            data = self._to_batch_type(record=record, event_type=self.event_type, model=self.model)
            if self._handler_accepts_lambda_context:
                result = await self.handler(record=data, lambda_context=self.lambda_context)
            else:
                result = await self.handler(record=data)

            return self.success_handler(record=record, result=result)
        except Exception as exc:
            # NOTE: Pydantic is an optional dependency, but when used and a poison pill scenario happens
            # we need to handle that exception differently.
            # We check for a public attr in validation errors coming from Pydantic exceptions (subclass or not)
            # and we compare if it's coming from the same model that trigger the exception in the first place

            # Pydantic v1 raises a ValidationError with ErrorWrappers and store the model instance in a class variable.
            # Pydantic v2 simplifies this by adding a title variable to store the model name directly.
            model = getattr(exc, "model", None) or getattr(exc, "title", None)
            model_name = getattr(self.model, "__name__", None)

            if model in (self.model, model_name):
                return self._register_model_validation_error_record(record)

            return self.failure_handler(record=data, exception=sys.exc_info())

Ancestors

• BasePartialBatchProcessor
• BasePartialProcessor
• abc.ABC

Inherited members

• BasePartialBatchProcessor:
  • async_process
  • failure_handler
  • process
  • response
  • success_handler

class BasePartialBatchProcessor (event_type: EventType, model: Optional[ForwardRef('BatchTypeModels')] = None)

Abstract class for batch processors.

Process batch and partially report failed items

Parameters

event_type : EventType

Whether this is a SQS, DynamoDB Streams, or Kinesis Data Stream event

model : Optional["BatchTypeModels"]

Parser's data model using either SqsRecordModel, DynamoDBStreamRecordModel, KinesisDataStreamRecord

Exceptions

BatchProcessingError Raised when the entire batch has failed processing

Expand source code

class BasePartialBatchProcessor(BasePartialProcessor):  # noqa
    DEFAULT_RESPONSE: PartialItemFailureResponse = {"batchItemFailures": []}

    def __init__(self, event_type: EventType, model: Optional["BatchTypeModels"] = None):
        """Process batch and partially report failed items

        Parameters
        ----------
        event_type: EventType
            Whether this is a SQS, DynamoDB Streams, or Kinesis Data Stream event
        model: Optional["BatchTypeModels"]
            Parser's data model using either SqsRecordModel, DynamoDBStreamRecordModel, KinesisDataStreamRecord

        Exceptions
        ----------
        BatchProcessingError
            Raised when the entire batch has failed processing
        """
        self.event_type = event_type
        self.model = model
        self.batch_response: PartialItemFailureResponse = copy.deepcopy(self.DEFAULT_RESPONSE)
        self._COLLECTOR_MAPPING = {
            EventType.SQS: self._collect_sqs_failures,
            EventType.KinesisDataStreams: self._collect_kinesis_failures,
            EventType.DynamoDBStreams: self._collect_dynamodb_failures,
        }
        self._DATA_CLASS_MAPPING = {
            EventType.SQS: SQSRecord,
            EventType.KinesisDataStreams: KinesisStreamRecord,
            EventType.DynamoDBStreams: DynamoDBRecord,
        }

        super().__init__()

    def response(self) -> PartialItemFailureResponse:
        """Batch items that failed processing, if any"""
        return self.batch_response

    def _prepare(self):
        """
        Remove results from previous execution.
        """
        self.success_messages.clear()
        self.fail_messages.clear()
        self.exceptions.clear()
        self.batch_response = copy.deepcopy(self.DEFAULT_RESPONSE)

    def _clean(self):
        """
        Report messages to be deleted in case of partial failure.
        """

        if not self._has_messages_to_report():
            return

        if self._entire_batch_failed():
            raise BatchProcessingError(
                msg=f"All records failed processing. {len(self.exceptions)} individual errors logged "
                f"separately below.",
                child_exceptions=self.exceptions,
            )

        messages = self._get_messages_to_report()
        self.batch_response = {"batchItemFailures": messages}

    def _has_messages_to_report(self) -> bool:
        if self.fail_messages:
            return True

        logger.debug(f"All {len(self.success_messages)} records successfully processed")
        return False

    def _entire_batch_failed(self) -> bool:
        return len(self.exceptions) == len(self.records)

    def _get_messages_to_report(self) -> List[PartialItemFailures]:
        """
        Format messages to use in batch deletion
        """
        return self._COLLECTOR_MAPPING[self.event_type]()

    # Event Source Data Classes follow python idioms for fields
    # while Parser/Pydantic follows the event field names to the latter
    def _collect_sqs_failures(self):
        failures = []
        for msg in self.fail_messages:
            # If a message failed due to model validation (e.g., poison pill)
            # we convert to an event source data class...but self.model is still true
            # therefore, we do an additional check on whether the failed message is still a model
            # see https://github.com/aws-powertools/powertools-lambda-python/issues/2091
            if self.model and getattr(msg, "parse_obj", None):
                msg_id = msg.messageId
            else:
                msg_id = msg.message_id
            failures.append({"itemIdentifier": msg_id})
        return failures

    def _collect_kinesis_failures(self):
        failures = []
        for msg in self.fail_messages:
            # # see https://github.com/aws-powertools/powertools-lambda-python/issues/2091
            if self.model and getattr(msg, "parse_obj", None):
                msg_id = msg.kinesis.sequenceNumber
            else:
                msg_id = msg.kinesis.sequence_number
            failures.append({"itemIdentifier": msg_id})
        return failures

    def _collect_dynamodb_failures(self):
        failures = []
        for msg in self.fail_messages:
            # see https://github.com/aws-powertools/powertools-lambda-python/issues/2091
            if self.model and getattr(msg, "parse_obj", None):
                msg_id = msg.dynamodb.SequenceNumber
            else:
                msg_id = msg.dynamodb.sequence_number
            failures.append({"itemIdentifier": msg_id})
        return failures

    @overload
    def _to_batch_type(
        self,
        record: dict,
        event_type: EventType,
        model: "BatchTypeModels",
    ) -> "BatchTypeModels": ...  # pragma: no cover

    @overload
    def _to_batch_type(self, record: dict, event_type: EventType) -> EventSourceDataClassTypes: ...  # pragma: no cover

    def _to_batch_type(self, record: dict, event_type: EventType, model: Optional["BatchTypeModels"] = None):
        if model is not None:
            # If a model is provided, we assume Pydantic is installed and we need to disable v2 warnings
            from aws_lambda_powertools.utilities.parser.compat import disable_pydantic_v2_warning

            disable_pydantic_v2_warning()

            return model.parse_obj(record)
        return self._DATA_CLASS_MAPPING[event_type](record)

    def _register_model_validation_error_record(self, record: dict):
        """Convert and register failure due to poison pills where model failed validation early"""
        # Parser will fail validation if record is a poison pill (malformed input)
        # this means we can't collect the message id if we try transforming again
        # so we convert into to the equivalent batch type model (e.g., SQS, Kinesis, DynamoDB Stream)
        # and downstream we can correctly collect the correct message id identifier and make the failed record available
        # see https://github.com/aws-powertools/powertools-lambda-python/issues/2091
        logger.debug("Record cannot be converted to customer's model; converting without model")
        failed_record: "EventSourceDataClassTypes" = self._to_batch_type(record=record, event_type=self.event_type)
        return self.failure_handler(record=failed_record, exception=sys.exc_info())

Ancestors

• BasePartialProcessor
• abc.ABC

Subclasses

• AsyncBatchProcessor
• BatchProcessor

Class variables

var DEFAULT_RESPONSE : PartialItemFailureResponse

Methods

def response(self) ‑> PartialItemFailureResponse

Batch items that failed processing, if any

Inherited members

• BasePartialProcessor:
  • async_process
  • failure_handler
  • process
  • success_handler

class BasePartialProcessor

Abstract class for batch processors.

Expand source code

class BasePartialProcessor(ABC):
    """
    Abstract class for batch processors.
    """

    lambda_context: LambdaContext

    def __init__(self):
        self.success_messages: List[BatchEventTypes] = []
        self.fail_messages: List[BatchEventTypes] = []
        self.exceptions: List[ExceptionInfo] = []

    @abstractmethod
    def _prepare(self):
        """
        Prepare context manager.
        """
        raise NotImplementedError()

    @abstractmethod
    def _clean(self):
        """
        Clear context manager.
        """
        raise NotImplementedError()

    @abstractmethod
    def _process_record(self, record: dict):
        """
        Process record with handler.
        """
        raise NotImplementedError()

    def process(self) -> List[Tuple]:
        """
        Call instance's handler for each record.
        """
        return [self._process_record(record) for record in self.records]

    @abstractmethod
    async def _async_process_record(self, record: dict):
        """
        Async process record with handler.
        """
        raise NotImplementedError()

    def async_process(self) -> List[Tuple]:
        """
        Async call instance's handler for each record.

        Note
        ----

        We keep the outer function synchronous to prevent making Lambda handler async, so to not impact
        customers' existing middlewares. Instead, we create an async closure to handle asynchrony.

        We also handle edge cases like Lambda container thaw by getting an existing or creating an event loop.

        See: https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtime-environment.html#runtimes-lifecycle-shutdown
        """

        async def async_process_closure():
            return list(await asyncio.gather(*[self._async_process_record(record) for record in self.records]))

        # WARNING
        # Do not use "asyncio.run(async_process())" due to Lambda container thaws/freeze, otherwise we might get "Event Loop is closed" # noqa: E501
        # Instead, get_event_loop() can also create one if a previous was erroneously closed
        # Mangum library does this as well. It's battle tested with other popular async-only frameworks like FastAPI
        # https://github.com/jordaneremieff/mangum/discussions/256#discussioncomment-2638946
        # https://github.com/jordaneremieff/mangum/blob/b85cd4a97f8ddd56094ccc540ca7156c76081745/mangum/protocols/http.py#L44

        # Let's prime the coroutine and decide
        # whether we create an event loop (Lambda) or schedule it as usual (non-Lambda)
        coro = async_process_closure()
        if os.getenv(constants.LAMBDA_TASK_ROOT_ENV):
            loop = asyncio.get_event_loop()  # NOTE: this might return an error starting in Python 3.12 in a few years
            task_instance = loop.create_task(coro)
            return loop.run_until_complete(task_instance)

        # Non-Lambda environment, run coroutine as usual
        return asyncio.run(coro)

    def __enter__(self):
        self._prepare()
        return self

    def __exit__(self, exception_type, exception_value, traceback):
        self._clean()

    def __call__(self, records: List[dict], handler: Callable, lambda_context: Optional[LambdaContext] = None):
        """
        Set instance attributes before execution

        Parameters
        ----------
        records: List[dict]
            List with objects to be processed.
        handler: Callable
            Callable to process "records" entries.
        """
        self.records = records
        self.handler = handler

        # NOTE: If a record handler has `lambda_context` parameter in its function signature, we inject it.
        # This is the earliest we can inspect for signature to prevent impacting performance.
        #
        #   Mechanism:
        #
        #   1. When using the `@batch_processor` decorator, this happens automatically.
        #   2. When using the context manager, customers have to include `lambda_context` param.
        #
        #   Scenario: Injects Lambda context
        #
        #   def record_handler(record, lambda_context): ... # noqa: ERA001
        #   with processor(records=batch, handler=record_handler, lambda_context=context): ... # noqa: ERA001
        #
        #   Scenario: Does NOT inject Lambda context (default)
        #
        #   def record_handler(record): pass # noqa: ERA001
        #   with processor(records=batch, handler=record_handler): ... # noqa: ERA001
        #
        if lambda_context is None:
            self._handler_accepts_lambda_context = False
        else:
            self.lambda_context = lambda_context
            self._handler_accepts_lambda_context = "lambda_context" in inspect.signature(self.handler).parameters

        return self

    def success_handler(self, record, result: Any) -> SuccessResponse:
        """
        Keeps track of batch records that were processed successfully

        Parameters
        ----------
        record: Any
            record that succeeded processing
        result: Any
            result from record handler

        Returns
        -------
        SuccessResponse
            "success", result, original record
        """
        entry = ("success", result, record)
        self.success_messages.append(record)
        return entry

    def failure_handler(self, record, exception: ExceptionInfo) -> FailureResponse:
        """
        Keeps track of batch records that failed processing

        Parameters
        ----------
        record: Any
            record that failed processing
        exception: ExceptionInfo
            Exception information containing type, value, and traceback (sys.exc_info())

        Returns
        -------
        FailureResponse
            "fail", exceptions args, original record
        """
        exception_string = f"{exception[0]}:{exception[1]}"
        entry = ("fail", exception_string, record)
        logger.debug(f"Record processing exception: {exception_string}")
        self.exceptions.append(exception)
        self.fail_messages.append(record)
        return entry

Ancestors

• abc.ABC

Subclasses

• BasePartialBatchProcessor

Class variables

var lambda_context : LambdaContext

Methods

def async_process(self) ‑> List[Tuple]

Async call instance's handler for each record.

Note

We keep the outer function synchronous to prevent making Lambda handler async, so to not impact customers' existing middlewares. Instead, we create an async closure to handle asynchrony.

We also handle edge cases like Lambda container thaw by getting an existing or creating an event loop.

See: https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtime-environment.html#runtimes-lifecycle-shutdown

def failure_handler(self, record, exception: Tuple[Optional[Type[BaseException]], Optional[BaseException], Optional[traceback]]) ‑> Tuple[str, str, Union[SQSRecord, KinesisStreamRecord, DynamoDBRecord, BatchTypeModels]]

Keeps track of batch records that failed processing

Parameters

record : Any

record that failed processing

exception : ExceptionInfo

Exception information containing type, value, and traceback (sys.exc_info())

Returns

FailureResponse

"fail", exceptions args, original record

def process(self) ‑> List[Tuple]

Call instance's handler for each record.

def success_handler(self, record, result: Any) ‑> Tuple[str, Any, Union[SQSRecord, KinesisStreamRecord, DynamoDBRecord, BatchTypeModels]]

Keeps track of batch records that were processed successfully

Parameters

record : Any

record that succeeded processing

result : Any

result from record handler

Returns

SuccessResponse

"success", result, original record

class BatchProcessor (event_type: EventType, model: Optional[ForwardRef('BatchTypeModels')] = None)

Process native partial responses from SQS, Kinesis Data Streams, and DynamoDB.

Example

Process batch triggered by SQS

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = BatchProcessor(event_type=EventType.SQS)
tracer = Tracer()
logger = Logger()


@tracer.capture_method
def record_handler(record: SQSRecord):
    payload: str = record.body
    if payload:
        item: dict = json.loads(payload)
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
@batch_processor(record_handler=record_handler, processor=processor)
def lambda_handler(event, context: LambdaContext):
    return processor.response()

Process batch triggered by Kinesis Data Streams

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.kinesis_stream_event import KinesisStreamRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = BatchProcessor(event_type=EventType.KinesisDataStreams)
tracer = Tracer()
logger = Logger()


@tracer.capture_method
def record_handler(record: KinesisStreamRecord):
    logger.info(record.kinesis.data_as_text)
    payload: dict = record.kinesis.data_as_json()
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
@batch_processor(record_handler=record_handler, processor=processor)
def lambda_handler(event, context: LambdaContext):
    return processor.response()

Process batch triggered by DynamoDB Data Streams

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.dynamo_db_stream_event import DynamoDBRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = BatchProcessor(event_type=EventType.DynamoDBStreams)
tracer = Tracer()
logger = Logger()


@tracer.capture_method
def record_handler(record: DynamoDBRecord):
    logger.info(record.dynamodb.new_image)
    payload: dict = json.loads(record.dynamodb.new_image.get("item"))
    # alternatively:
    # changes: Dict[str, Any] = record.dynamodb.new_image  # noqa: ERA001
    # payload = change.get("Message") -> "<payload>"
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
def lambda_handler(event, context: LambdaContext):
    batch = event["Records"]
    with processor(records=batch, processor=processor):
        processed_messages = processor.process() # kick off processing, return list[tuple]

    return processor.response()

Raises

BatchProcessingError

When all batch records fail processing

Limitations

• Async record handler not supported, use AsyncBatchProcessor instead.

Process batch and partially report failed items

Parameters

event_type : EventType

Whether this is a SQS, DynamoDB Streams, or Kinesis Data Stream event

model : Optional["BatchTypeModels"]

Parser's data model using either SqsRecordModel, DynamoDBStreamRecordModel, KinesisDataStreamRecord

Exceptions

BatchProcessingError Raised when the entire batch has failed processing

Expand source code

class BatchProcessor(BasePartialBatchProcessor):  # Keep old name for compatibility
    """Process native partial responses from SQS, Kinesis Data Streams, and DynamoDB.

    Example
    -------

    ## Process batch triggered by SQS

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = BatchProcessor(event_type=EventType.SQS)
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    def record_handler(record: SQSRecord):
        payload: str = record.body
        if payload:
            item: dict = json.loads(payload)
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    @batch_processor(record_handler=record_handler, processor=processor)
    def lambda_handler(event, context: LambdaContext):
        return processor.response()
    ```

    ## Process batch triggered by Kinesis Data Streams

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.kinesis_stream_event import KinesisStreamRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = BatchProcessor(event_type=EventType.KinesisDataStreams)
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    def record_handler(record: KinesisStreamRecord):
        logger.info(record.kinesis.data_as_text)
        payload: dict = record.kinesis.data_as_json()
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    @batch_processor(record_handler=record_handler, processor=processor)
    def lambda_handler(event, context: LambdaContext):
        return processor.response()
    ```

    ## Process batch triggered by DynamoDB Data Streams

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.dynamo_db_stream_event import DynamoDBRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = BatchProcessor(event_type=EventType.DynamoDBStreams)
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    def record_handler(record: DynamoDBRecord):
        logger.info(record.dynamodb.new_image)
        payload: dict = json.loads(record.dynamodb.new_image.get("item"))
        # alternatively:
        # changes: Dict[str, Any] = record.dynamodb.new_image  # noqa: ERA001
        # payload = change.get("Message") -> "<payload>"
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    def lambda_handler(event, context: LambdaContext):
        batch = event["Records"]
        with processor(records=batch, processor=processor):
            processed_messages = processor.process() # kick off processing, return list[tuple]

        return processor.response()
    ```


    Raises
    ------
    BatchProcessingError
        When all batch records fail processing

    Limitations
    -----------
    * Async record handler not supported, use AsyncBatchProcessor instead.
    """

    async def _async_process_record(self, record: dict):
        raise NotImplementedError()

    def _process_record(self, record: dict) -> Union[SuccessResponse, FailureResponse]:
        """
        Process a record with instance's handler

        Parameters
        ----------
        record: dict
            A batch record to be processed.
        """
        data: Optional["BatchTypeModels"] = None
        try:
            data = self._to_batch_type(record=record, event_type=self.event_type, model=self.model)
            if self._handler_accepts_lambda_context:
                result = self.handler(record=data, lambda_context=self.lambda_context)
            else:
                result = self.handler(record=data)

            return self.success_handler(record=record, result=result)
        except Exception as exc:
            # NOTE: Pydantic is an optional dependency, but when used and a poison pill scenario happens
            # we need to handle that exception differently.
            # We check for a public attr in validation errors coming from Pydantic exceptions (subclass or not)
            # and we compare if it's coming from the same model that trigger the exception in the first place

            # Pydantic v1 raises a ValidationError with ErrorWrappers and store the model instance in a class variable.
            # Pydantic v2 simplifies this by adding a title variable to store the model name directly.
            model = getattr(exc, "model", None) or getattr(exc, "title", None)
            model_name = getattr(self.model, "__name__", None)

            if model in (self.model, model_name):
                return self._register_model_validation_error_record(record)

            return self.failure_handler(record=data, exception=sys.exc_info())

Ancestors

• BasePartialBatchProcessor
• BasePartialProcessor
• abc.ABC

Subclasses

• SqsFifoPartialProcessor

Inherited members

• BasePartialBatchProcessor:
  • async_process
  • failure_handler
  • process
  • response
  • success_handler

class EventType (*args, **kwds)

Create a collection of name/value pairs.

Example enumeration:

>>> class Color(Enum):
...     RED = 1
...     BLUE = 2
...     GREEN = 3

Access them by:

• attribute access:

Color.RED

• value lookup:

Color(1)

• name lookup:

Color['RED']

Enumerations can be iterated over, and know how many members they have:

>>> len(Color)
3

>>> list(Color)
[<Color.RED: 1>, <Color.BLUE: 2>, <Color.GREEN: 3>]

Methods can be added to enumerations, and members can have their own attributes – see the documentation for details.

Expand source code

class EventType(Enum):
    SQS = "SQS"
    KinesisDataStreams = "KinesisDataStreams"
    DynamoDBStreams = "DynamoDBStreams"

Ancestors

• enum.Enum

Class variables

var DynamoDBStreams

var KinesisDataStreams

var SQS

class SqsFifoPartialProcessor (model: Optional[ForwardRef('BatchSqsTypeModel')] = None, skip_group_on_error: bool = False)

Process native partial responses from SQS FIFO queues.

Stops processing records when the first record fails. The remaining records are reported as failed items.

Example

---

Process batch triggered by a FIFO SQS

import json

from aws_lambda_powertools import Logger, Tracer
from aws_lambda_powertools.utilities.batch import SqsFifoPartialProcessor, EventType, batch_processor
from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
from aws_lambda_powertools.utilities.typing import LambdaContext


processor = SqsFifoPartialProcessor()
tracer = Tracer()
logger = Logger()


@tracer.capture_method
def record_handler(record: SQSRecord):
    payload: str = record.body
    if payload:
        item: dict = json.loads(payload)
    ...

@logger.inject_lambda_context
@tracer.capture_lambda_handler
@batch_processor(record_handler=record_handler, processor=processor)
def lambda_handler(event, context: LambdaContext):
    return processor.response()

Initialize the SqsFifoProcessor.

Parameters

model : Optional["BatchSqsTypeModel"]

An optional model for batch processing.

skip_group_on_error : bool

Determines whether to exclusively skip messages from the MessageGroupID that encountered processing failures Default is False.

Expand source code

class SqsFifoPartialProcessor(BatchProcessor):
    """Process native partial responses from SQS FIFO queues.

    Stops processing records when the first record fails. The remaining records are reported as failed items.

    Example
    _______

    ## Process batch triggered by a FIFO SQS

    ```python
    import json

    from aws_lambda_powertools import Logger, Tracer
    from aws_lambda_powertools.utilities.batch import SqsFifoPartialProcessor, EventType, batch_processor
    from aws_lambda_powertools.utilities.data_classes.sqs_event import SQSRecord
    from aws_lambda_powertools.utilities.typing import LambdaContext


    processor = SqsFifoPartialProcessor()
    tracer = Tracer()
    logger = Logger()


    @tracer.capture_method
    def record_handler(record: SQSRecord):
        payload: str = record.body
        if payload:
            item: dict = json.loads(payload)
        ...

    @logger.inject_lambda_context
    @tracer.capture_lambda_handler
    @batch_processor(record_handler=record_handler, processor=processor)
    def lambda_handler(event, context: LambdaContext):
        return processor.response()
    ```
    """

    circuit_breaker_exc = (
        SQSFifoCircuitBreakerError,
        SQSFifoCircuitBreakerError("A previous record failed processing"),
        None,
    )

    group_circuit_breaker_exc = (
        SQSFifoMessageGroupCircuitBreakerError,
        SQSFifoMessageGroupCircuitBreakerError("A previous record from this message group failed processing"),
        None,
    )

    def __init__(self, model: Optional["BatchSqsTypeModel"] = None, skip_group_on_error: bool = False):
        """
        Initialize the SqsFifoProcessor.

        Parameters
        ----------
        model: Optional["BatchSqsTypeModel"]
            An optional model for batch processing.
        skip_group_on_error: bool
            Determines whether to exclusively skip messages from the MessageGroupID that encountered processing failures
            Default is False.

        """
        self._skip_group_on_error: bool = skip_group_on_error
        self._current_group_id = None
        self._failed_group_ids: Set[str] = set()
        super().__init__(EventType.SQS, model)

    def _process_record(self, record):
        self._current_group_id = record.get("attributes", {}).get("MessageGroupId")

        # Short-circuits the process if:
        #     - There are failed messages, OR
        #     - The `skip_group_on_error` option is on, and the current message is part of a failed group.
        fail_entire_batch = bool(self.fail_messages) and not self._skip_group_on_error
        fail_group_id = self._skip_group_on_error and self._current_group_id in self._failed_group_ids
        if fail_entire_batch or fail_group_id:
            return self.failure_handler(
                record=self._to_batch_type(record, event_type=self.event_type, model=self.model),
                exception=self.group_circuit_breaker_exc if self._skip_group_on_error else self.circuit_breaker_exc,
            )

        return super()._process_record(record)

    def failure_handler(self, record, exception: ExceptionInfo) -> FailureResponse:
        # If we are failing a message and the `skip_group_on_error` is on, we store the failed group ID
        # This way, future messages with the same group ID will be failed automatically.
        if self._skip_group_on_error and self._current_group_id:
            self._failed_group_ids.add(self._current_group_id)

        return super().failure_handler(record, exception)

    def _clean(self):
        self._failed_group_ids.clear()
        self._current_group_id = None

        super()._clean()

    async def _async_process_record(self, record: dict):
        raise NotImplementedError()

Ancestors

• BatchProcessor
• BasePartialBatchProcessor
• BasePartialProcessor
• abc.ABC

Class variables

var circuit_breaker_exc

var group_circuit_breaker_exc

Inherited members

• BatchProcessor:
  • async_process
  • failure_handler
  • process
  • response
  • success_handler