Module aws_lambda_powertools.logging.logger

Functions

def log_uncaught_exception_hook(exc_type,
exc_value,
exc_traceback,
logger: Logger) ‑> None
Expand source code
def log_uncaught_exception_hook(exc_type, exc_value, exc_traceback, logger: Logger) -> None:
    """Callback function for sys.excepthook to use Logger to log uncaught exceptions"""
    logger.exception(exc_value, exc_info=(exc_type, exc_value, exc_traceback))  # pragma: no cover

Callback function for sys.excepthook to use Logger to log uncaught exceptions

def set_package_logger(level: str | int = 10,
stream: IO[str] | None = None,
formatter: logging.Formatter | None = None) ‑> None
Expand source code
def set_package_logger(
    level: str | int = logging.DEBUG,
    stream: IO[str] | None = None,
    formatter: logging.Formatter | None = None,
) -> None:
    
"""Set an additional stream handler, formatter, and log level for aws_lambda_powertools package logger. **Package log by default is suppressed (NullHandler), this should only used for debugging. This is separate from application Logger class utility** Example ------- **Enables debug logging for Powertools for AWS Lambda (Python) package** >>> aws_lambda_powertools.logging.logger import set_package_logger >>> set_package_logger() Parameters ---------- level: str, int log level, DEBUG by default stream: sys.stdout log stream, stdout by default formatter: logging.Formatter log formatter, "%(asctime)s %(name)s [%(levelname)s] %(message)s" by default """
if formatter is None: formatter = logging.Formatter("%(asctime)s %(name)s [%(levelname)s] %(message)s") if stream is None: stream = sys.stdout logger = logging.getLogger("aws_lambda_powertools") logger.setLevel(level) handler = logging.StreamHandler(stream) handler.setFormatter(formatter) logger.addHandler(handler)

Set an additional stream handler, formatter, and log level for aws_lambda_powertools package logger.

Package log by default is suppressed (NullHandler), this should only used for debugging. This is separate from application Logger class utility

Example

Enables debug logging for Powertools for AWS Lambda (Python) package

>>> aws_lambda_powertools.logging.logger import set_package_logger
>>> set_package_logger()

Parameters

level : str, int
log level, DEBUG by default
stream : sys.stdout
log stream, stdout by default
formatter : logging.Formatter
log formatter, "%(asctime)s %(name)s [%(levelname)s] %(message)s" by default

Classes

class Logger (service: str | None = None,
level: str | int | None = None,
child: bool = False,
sampling_rate: float | None = None,
stream: IO[str] | None = None,
logger_formatter: PowertoolsFormatter | None = None,
logger_handler: logging.Handler | None = None,
log_uncaught_exceptions: bool = False,
json_serializer: Callable[[dict], str] | None = None,
json_deserializer: Callable[[dict | str | bool | int | float], str] | None = None,
json_default: Callable[[Any], Any] | None = None,
datefmt: str | None = None,
use_datetime_directive: bool = False,
log_record_order: list[str] | None = None,
utc: bool = False,
use_rfc3339: bool = False,
serialize_stacktrace: bool = True,
**kwargs)
Expand source code
class Logger:
    
"""Creates and setups a logger to format statements in JSON. Includes service name and any additional key=value into logs It also accepts both service name or level explicitly via env vars Environment variables --------------------- POWERTOOLS_SERVICE_NAME : str service name POWERTOOLS_LOG_LEVEL: str logging level (e.g. INFO, DEBUG) POWERTOOLS_LOGGER_SAMPLE_RATE: float sampling rate ranging from 0 to 1, 1 being 100% sampling Parameters ---------- service : str, optional service name to be appended in logs, by default "service_undefined" level : str, int optional The level to set. Can be a string representing the level name: 'DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL' or an integer representing the level value: 10 for 'DEBUG', 20 for 'INFO', 30 for 'WARNING', 40 for 'ERROR', 50 for 'CRITICAL'. by default "INFO" child: bool, optional create a child Logger named <service>.<caller_file_name>, False by default sample_rate: float, optional sample rate for debug calls within execution context defaults to 0.0 stream: sys.stdout, optional valid output for a logging stream, by default sys.stdout logger_formatter: PowertoolsFormatter, optional custom logging formatter that implements PowertoolsFormatter logger_handler: logging.Handler, optional custom logging handler e.g. logging.FileHandler("file.log") log_uncaught_exceptions: bool, by default False logs uncaught exception using sys.excepthook See: https://docs.python.org/3/library/sys.html#sys.excepthook Parameters propagated to LambdaPowertoolsFormatter -------------------------------------------------- datefmt: str, optional String directives (strftime) to format log timestamp using `time`, by default it uses 2021-05-03 11:47:12,494+0200. use_datetime_directive: bool, optional Interpret `datefmt` as a format string for `datetime.datetime.strftime`, rather than `time.strftime`. See https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior . This also supports a custom %F directive for milliseconds. use_rfc3339: bool, optional Whether to use a popular date format that complies with both RFC3339 and ISO8601. e.g., 2022-10-27T16:27:43.738+02:00. json_serializer : Callable, optional function to serialize `obj` to a JSON formatted `str`, by default json.dumps json_deserializer : Callable, optional function to deserialize `str`, `bytes`, bytearray` containing a JSON document to a Python `obj`, by default json.loads json_default : Callable, optional function to coerce unserializable values, by default `str()` Only used when no custom formatter is set utc : bool, optional set logging timestamp to UTC, by default False to continue to use local time as per stdlib log_record_order : list, optional set order of log keys when logging, by default ["level", "location", "message", "timestamp"] Example ------- **Setups structured logging in JSON for Lambda functions with explicit service name** >>> from aws_lambda_powertools import Logger >>> logger = Logger(service="payment") >>> >>> def handler(event, context): logger.info("Hello") **Setups structured logging in JSON for Lambda functions using env vars** $ export POWERTOOLS_SERVICE_NAME="payment" $ export POWERTOOLS_LOGGER_SAMPLE_RATE=0.01 # 1% debug sampling >>> from aws_lambda_powertools import Logger >>> logger = Logger() >>> >>> def handler(event, context): logger.info("Hello") **Append payment_id to previously setup logger** >>> from aws_lambda_powertools import Logger >>> logger = Logger(service="payment") >>> >>> def handler(event, context): logger.append_keys(payment_id=event["payment_id"]) logger.info("Hello") **Create child Logger using logging inheritance via child param** >>> # app.py >>> import another_file >>> from aws_lambda_powertools import Logger >>> logger = Logger(service="payment") >>> >>> # another_file.py >>> from aws_lambda_powertools import Logger >>> logger = Logger(service="payment", child=True) **Logging in UTC timezone** >>> # app.py >>> import logging >>> from aws_lambda_powertools import Logger >>> >>> logger = Logger(service="payment", utc=True) **Brings message as the first key in log statements** >>> # app.py >>> import logging >>> from aws_lambda_powertools import Logger >>> >>> logger = Logger(service="payment", log_record_order=["message"]) **Logging to a file instead of standard output for testing** >>> # app.py >>> import logging >>> from aws_lambda_powertools import Logger >>> >>> logger = Logger(service="payment", logger_handler=logging.FileHandler("log.json")) Raises ------ InvalidLoggerSamplingRateError When sampling rate provided is not a float """
# noqa: E501 def __init__( self, service: str | None = None, level: str | int | None = None, child: bool = False, sampling_rate: float | None = None, stream: IO[str] | None = None, logger_formatter: PowertoolsFormatter | None = None, logger_handler: logging.Handler | None = None, log_uncaught_exceptions: bool = False, json_serializer: Callable[[dict], str] | None = None, json_deserializer: Callable[[dict | str | bool | int | float], str] | None = None, json_default: Callable[[Any], Any] | None = None, datefmt: str | None = None, use_datetime_directive: bool = False, log_record_order: list[str] | None = None, utc: bool = False, use_rfc3339: bool = False, serialize_stacktrace: bool = True, **kwargs, ) -> None: self.service = resolve_env_var_choice( choice=service, env=os.getenv(constants.SERVICE_NAME_ENV, "service_undefined"), ) self.sampling_rate = resolve_env_var_choice( choice=sampling_rate, env=os.getenv(constants.LOGGER_LOG_SAMPLING_RATE), ) self.child = child self.logger_formatter = logger_formatter self._stream = stream or sys.stdout self.logger_handler = logger_handler or logging.StreamHandler(self._stream) self.log_uncaught_exceptions = log_uncaught_exceptions self._is_deduplication_disabled = resolve_truthy_env_var_choice( env=os.getenv(constants.LOGGER_LOG_DEDUPLICATION_ENV, "false"), ) self._default_log_keys = {"service": self.service, "sampling_rate": self.sampling_rate} self._logger = self._get_logger() # NOTE: This is primarily to improve UX, so IDEs can autocomplete LambdaPowertoolsFormatter options # previously, we masked all of them as kwargs thus limiting feature discovery formatter_options = { "json_serializer": json_serializer, "json_deserializer": json_deserializer, "json_default": json_default, "datefmt": datefmt, "use_datetime_directive": use_datetime_directive, "log_record_order": log_record_order, "utc": utc, "use_rfc3339": use_rfc3339, "serialize_stacktrace": serialize_stacktrace, } self._init_logger(formatter_options=formatter_options, log_level=level, **kwargs) if self.log_uncaught_exceptions: logger.debug("Replacing exception hook") sys.excepthook = functools.partial(log_uncaught_exception_hook, logger=self) # Prevent __getattr__ from shielding unknown attribute errors in type checkers # https://github.com/aws-powertools/powertools-lambda-python/issues/1660 if not TYPE_CHECKING: # pragma: no cover def __getattr__(self, name): # Proxy attributes not found to actual logger to support backward compatibility # https://github.com/aws-powertools/powertools-lambda-python/issues/97 return getattr(self._logger, name) def _get_logger(self) -> logging.Logger: """Returns a Logger named {self.service}, or {self.service.filename} for child loggers""" logger_name = self.service if self.child: logger_name = f"{self.service}.{_get_caller_filename()}" return logging.getLogger(logger_name) def _init_logger( self, formatter_options: dict | None = None, log_level: str | int | None = None, **kwargs, ) -> None: """Configures new logger""" # Skip configuration if it's a child logger or a pre-configured logger # to prevent the following: # a) multiple handlers being attached # b) different sampling mechanisms # c) multiple messages from being logged as handlers can be duplicated is_logger_preconfigured = getattr(self._logger, LOGGER_ATTRIBUTE_PRECONFIGURED, False) if self.child: self.setLevel(log_level) return if is_logger_preconfigured: return self.setLevel(log_level) self._configure_sampling() self.addHandler(self.logger_handler) self.structure_logs(formatter_options=formatter_options, **kwargs) # Pytest Live Log feature duplicates log records for colored output # but we explicitly add a filter for log deduplication. # This flag disables this protection when you explicit want logs to be duplicated (#262) if not self._is_deduplication_disabled: logger.debug("Adding filter in root logger to suppress child logger records to bubble up") for handler in logging.root.handlers: # It'll add a filter to suppress any child logger from self.service # Example: `Logger(service="order")`, where service is Order # It'll reject all loggers starting with `order` e.g. order.checkout, order.shared handler.addFilter(SuppressFilter(self.service)) # as per bug in #249, we should not be pre-configuring an existing logger # therefore we set a custom attribute in the Logger that will be returned # std logging will return the same Logger with our attribute if name is reused logger.debug(f"Marking logger {self.service} as preconfigured") self._logger.init = True # type: ignore[attr-defined] def _configure_sampling(self) -> None: """Dynamically set log level based on sampling rate Raises ------ InvalidLoggerSamplingRateError When sampling rate provided is not a float """ try: if self.sampling_rate and random.random() <= float(self.sampling_rate): logger.debug("Setting log level to Debug due to sampling rate") self._logger.setLevel(logging.DEBUG) except ValueError: raise InvalidLoggerSamplingRateError( ( f"Expected a float value ranging 0 to 1, but received {self.sampling_rate} instead." "Please review POWERTOOLS_LOGGER_SAMPLE_RATE environment variable." ), ) @overload def inject_lambda_context( self, lambda_handler: AnyCallableT, log_event: bool | None = None, correlation_id_path: str | None = None, clear_state: bool | None = False, ) -> AnyCallableT: ... @overload def inject_lambda_context( self, lambda_handler: None = None, log_event: bool | None = None, correlation_id_path: str | None = None, clear_state: bool | None = False, ) -> Callable[[AnyCallableT], AnyCallableT]: ... def inject_lambda_context( self, lambda_handler: AnyCallableT | None = None, log_event: bool | None = None, correlation_id_path: str | None = None, clear_state: bool | None = False, ) -> Any:
"""Decorator to capture Lambda contextual info and inject into logger Parameters ---------- clear_state : bool, optional Instructs logger to remove any custom keys previously added lambda_handler : Callable Method to inject the lambda context log_event : bool, optional Instructs logger to log Lambda Event, by default False correlation_id_path: str, optional Optional JMESPath for the correlation_id Environment variables --------------------- POWERTOOLS_LOGGER_LOG_EVENT : str instruct logger to log Lambda Event (e.g. `"true", "True", "TRUE"`) Example ------- **Captures Lambda contextual runtime info (e.g memory, arn, req_id)** from aws_lambda_powertools import Logger logger = Logger(service="payment") @logger.inject_lambda_context def handler(event, context): logger.info("Hello") **Captures Lambda contextual runtime info and logs incoming request** from aws_lambda_powertools import Logger logger = Logger(service="payment") @logger.inject_lambda_context(log_event=True) def handler(event, context): logger.info("Hello") Returns ------- decorate : Callable Decorated lambda handler """
# If handler is None we've been called with parameters # Return a partial function with args filled if lambda_handler is None: logger.debug("Decorator called with parameters") return functools.partial( self.inject_lambda_context, log_event=log_event, correlation_id_path=correlation_id_path, clear_state=clear_state, ) log_event = resolve_truthy_env_var_choice( env=os.getenv(constants.LOGGER_LOG_EVENT_ENV, "false"), choice=log_event, ) @functools.wraps(lambda_handler) def decorate(event, context, *args, **kwargs): lambda_context = build_lambda_context_model(context) cold_start = _is_cold_start() if clear_state: self.structure_logs(cold_start=cold_start, **lambda_context.__dict__) else: self.append_keys(cold_start=cold_start, **lambda_context.__dict__) if correlation_id_path: self.set_correlation_id( jmespath_utils.query(envelope=correlation_id_path, data=event), ) if log_event: logger.debug("Event received") self.info(extract_event_from_common_models(event)) return lambda_handler(event, context, *args, **kwargs) return decorate def info( self, msg: object, *args: object, exc_info: logging._ExcInfoType = None, stack_info: bool = False, stacklevel: int = 2, extra: Mapping[str, object] | None = None, **kwargs: object, ) -> None: extra = extra or {} extra = {**extra, **kwargs} return self._logger.info( msg, *args, exc_info=exc_info, stack_info=stack_info, stacklevel=stacklevel, extra=extra, ) def error( self, msg: object, *args: object, exc_info: logging._ExcInfoType = None, stack_info: bool = False, stacklevel: int = 2, extra: Mapping[str, object] | None = None, **kwargs: object, ) -> None: extra = extra or {} extra = {**extra, **kwargs} return self._logger.error( msg, *args, exc_info=exc_info, stack_info=stack_info, stacklevel=stacklevel, extra=extra, ) def exception( self, msg: object, *args: object, exc_info: logging._ExcInfoType = True, stack_info: bool = False, stacklevel: int = 2, extra: Mapping[str, object] | None = None, **kwargs: object, ) -> None: extra = extra or {} extra = {**extra, **kwargs} return self._logger.exception( msg, *args, exc_info=exc_info, stack_info=stack_info, stacklevel=stacklevel, extra=extra, ) def critical( self, msg: object, *args: object, exc_info: logging._ExcInfoType = None, stack_info: bool = False, stacklevel: int = 2, extra: Mapping[str, object] | None = None, **kwargs: object, ) -> None: extra = extra or {} extra = {**extra, **kwargs} return self._logger.critical( msg, *args, exc_info=exc_info, stack_info=stack_info, stacklevel=stacklevel, extra=extra, ) def warning( self, msg: object, *args: object, exc_info: logging._ExcInfoType = None, stack_info: bool = False, stacklevel: int = 2, extra: Mapping[str, object] | None = None, **kwargs: object, ) -> None: extra = extra or {} extra = {**extra, **kwargs} return self._logger.warning( msg, *args, exc_info=exc_info, stack_info=stack_info, stacklevel=stacklevel, extra=extra, ) def debug( self, msg: object, *args: object, exc_info: logging._ExcInfoType = None, stack_info: bool = False, stacklevel: int = 2, extra: Mapping[str, object] | None = None, **kwargs: object, ) -> None: extra = extra or {} extra = {**extra, **kwargs} return self._logger.debug( msg, *args, exc_info=exc_info, stack_info=stack_info, stacklevel=stacklevel, extra=extra, ) def append_keys(self, **additional_keys: object) -> None: self.registered_formatter.append_keys(**additional_keys) def get_current_keys(self) -> dict[str, Any]: return self.registered_formatter.get_current_keys() def remove_keys(self, keys: Iterable[str]) -> None: self.registered_formatter.remove_keys(keys) @contextmanager def append_context_keys(self, **additional_keys: Any) -> Generator[None, None, None]:
""" Context manager to temporarily add logging keys. Parameters: ----------- **keys: Any Key-value pairs to include in the log context during the lifespan of the context manager. Example: -------- >>> logger = Logger(service="example_service") >>> with logger.append_context_keys(user_id="123", operation="process"): >>> logger.info("Log with context") >>> logger.info("Log without context") """
with self.registered_formatter.append_context_keys(**additional_keys): yield # These specific thread-safe methods are necessary to manage shared context in concurrent environments. # They prevent race conditions and ensure data consistency across multiple threads. def thread_safe_append_keys(self, **additional_keys: object) -> None: # Append additional key-value pairs to the context safely in a thread-safe manner. self.registered_formatter.thread_safe_append_keys(**additional_keys) def thread_safe_get_current_keys(self) -> dict[str, Any]: # Retrieve the current context keys safely in a thread-safe manner. return self.registered_formatter.thread_safe_get_current_keys() def thread_safe_remove_keys(self, keys: Iterable[str]) -> None: # Remove specified keys from the context safely in a thread-safe manner. self.registered_formatter.thread_safe_remove_keys(keys) def thread_safe_clear_keys(self) -> None: # Clear all keys from the context safely in a thread-safe manner. self.registered_formatter.thread_safe_clear_keys() def structure_logs(self, append: bool = False, formatter_options: dict | None = None, **keys) -> None:
"""Sets logging formatting to JSON. Optionally, it can append keyword arguments to an existing logger, so it is available across future log statements. Last keyword argument and value wins if duplicated. Parameters ---------- append : bool, optional append keys provided to logger formatter, by default False formatter_options : dict, optional LambdaPowertoolsFormatter options to be propagated, by default {} """
formatter_options = formatter_options or {} # There are 3 operational modes for this method ## 1. Register a Powertools for AWS Lambda (Python) Formatter for the first time ## 2. Append new keys to the current logger formatter; deprecated in favour of append_keys ## 3. Add new keys and discard existing to the registered formatter # Mode 1 log_keys = {**self._default_log_keys, **keys} is_logger_preconfigured = getattr(self._logger, LOGGER_ATTRIBUTE_PRECONFIGURED, False) if not is_logger_preconfigured: formatter = self.logger_formatter or LambdaPowertoolsFormatter(**formatter_options, **log_keys) self.registered_handler.setFormatter(formatter) # when using a custom Powertools for AWS Lambda (Python) Formatter # standard and custom keys that are not Powertools for AWS Lambda (Python) Formatter parameters # should be appended and custom keys that might happen to be Powertools for AWS Lambda (Python) # Formatter parameters should be discarded this prevents adding them as custom keys, for example, # `json_default=<callable>` see https://github.com/aws-powertools/powertools-lambda-python/issues/1263 custom_keys = {k: v for k, v in log_keys.items() if k not in RESERVED_FORMATTER_CUSTOM_KEYS} return self.registered_formatter.append_keys(**custom_keys) # Mode 2 (legacy) if append: # Maintenance: Add deprecation warning for major version return self.append_keys(**keys) # Mode 3 self.registered_formatter.clear_state() self.registered_formatter.thread_safe_clear_keys() self.registered_formatter.append_keys(**log_keys) def set_correlation_id(self, value: str | None) -> None:
"""Sets the correlation_id in the logging json Parameters ---------- value : str, optional Value for the correlation id. None will remove the correlation_id """
self.append_keys(correlation_id=value) def get_correlation_id(self) -> str | None: """Gets the correlation_id in the logging json Returns ------- str, optional Value for the correlation id """ if isinstance(self.registered_formatter, LambdaPowertoolsFormatter): return self.registered_formatter.log_format.get("correlation_id") return None def setLevel(self, level: str | int | None) -> None: return self._logger.setLevel(self._determine_log_level(level)) def addHandler(self, handler: logging.Handler) -> None: return self._logger.addHandler(handler) def addFilter(self, filter: logging._FilterType) -> None: # noqa: A002 # filter built-in usage return self._logger.addFilter(filter) def removeFilter(self, filter: logging._FilterType) -> None: # noqa: A002 # filter built-in usage return self._logger.removeFilter(filter) @property def registered_handler(self) -> logging.Handler: """Convenience property to access the first logger handler""" # We ignore mypy here because self.child encodes whether or not self._logger.parent is # None, mypy can't see this from context but we can handlers = self._logger.parent.handlers if self.child else self._logger.handlers # type: ignore[union-attr] return handlers[0] @property def registered_formatter(self) -> BasePowertoolsFormatter: """Convenience property to access the first logger formatter""" return self.registered_handler.formatter # type: ignore[return-value] @property def log_level(self) -> int: return self._logger.level @property def name(self) -> str: return self._logger.name @property def handlers(self) -> list[logging.Handler]: """List of registered logging handlers Notes ----- Looking for the first configured handler? Use registered_handler property instead. """ return self._logger.handlers def _get_aws_lambda_log_level(self) -> str | None: """ Retrieve the log level for AWS Lambda from the Advanced Logging Controls feature. Returns: str | None: The corresponding logging level. """ return constants.LAMBDA_ADVANCED_LOGGING_LEVELS.get(os.getenv(constants.LAMBDA_LOG_LEVEL_ENV)) def _get_powertools_log_level(self, level: str | int | None) -> str | None:
"""Retrieve the log level for Powertools from the environment variable or level parameter. If log level is an integer, we convert to its respective string level `logging.getLevelName()`. If no log level is provided, we check env vars for the log level: POWERTOOLS_LOG_LEVEL_ENV and POWERTOOLS_LOG_LEVEL_LEGACY_ENV. Parameters: ----------- level : str | int | None The specified log level as a string, integer, or None. Environment variables --------------------- POWERTOOLS_LOG_LEVEL : str log level (e.g: INFO, DEBUG, WARNING, ERROR, CRITICAL) LOG_LEVEL (Legacy) : str log level (e.g: INFO, DEBUG, WARNING, ERROR, CRITICAL) Returns: -------- str | None: The corresponding logging level. Returns None if the log level is not explicitly specified. """
# noqa E501 # Extract log level from Powertools Logger env vars log_level_env = os.getenv(constants.POWERTOOLS_LOG_LEVEL_ENV) or os.getenv( constants.POWERTOOLS_LOG_LEVEL_LEGACY_ENV, ) # If level is an int (logging.INFO), return its respective string ("INFO") if isinstance(level, int): return logging.getLevelName(level) return level or log_level_env def _determine_log_level(self, level: str | int | None) -> str | int:
"""Determine the effective log level considering Lambda and Powertools preferences. It emits an UserWarning if Lambda ALC log level is lower than Logger log level. Parameters: ----------- level: str | int | None The specified log level as a string, integer, or None. Returns: ---------- str | int: The effective logging level. """
# This function consider the following order of precedence: # 1 - If a log level is set using AWS Lambda Advanced Logging Controls, it sets it. # 2 - If a log level is passed to the constructor, it sets it # 3 - If a log level is set via setLevel, it sets it. # 4 - If a log level is set via Powertools env variables, it sets it. # 5 - If none of the above is true, the default log level applies INFO. lambda_log_level = self._get_aws_lambda_log_level() powertools_log_level = self._get_powertools_log_level(level) if powertools_log_level and lambda_log_level: # If Powertools log level is set and higher than AWS Lambda Advanced Logging Controls, emit a warning if logging.getLevelName(lambda_log_level) > logging.getLevelName(powertools_log_level): warnings.warn( f"Current log level ({powertools_log_level}) does not match AWS Lambda Advanced Logging Controls " f"minimum log level ({lambda_log_level}). This can lead to data loss, consider adjusting them.", UserWarning, stacklevel=2, ) # AWS Lambda Advanced Logging Controls takes precedence over Powertools log level and we use this if lambda_log_level: return lambda_log_level # Check if Powertools log level is None, which means it's not set # We assume INFO as the default log level if powertools_log_level is None: return logging.INFO # Powertools log level is set, we use this return powertools_log_level.upper()

Creates and setups a logger to format statements in JSON.

Includes service name and any additional key=value into logs It also accepts both service name or level explicitly via env vars

Environment Variables

POWERTOOLS_SERVICE_NAME : str service name POWERTOOLS_LOG_LEVEL: str logging level (e.g. INFO, DEBUG) POWERTOOLS_LOGGER_SAMPLE_RATE: float sampling rate ranging from 0 to 1, 1 being 100% sampling

Parameters

service : str, optional
service name to be appended in logs, by default "service_undefined"
level : str, int optional
The level to set. Can be a string representing the level name: 'DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL' or an integer representing the level value: 10 for 'DEBUG', 20 for 'INFO', 30 for 'WARNING', 40 for 'ERROR', 50 for 'CRITICAL'. by default "INFO"
child : bool, optional
create a child Logger named ., False by default
sample_rate : float, optional
sample rate for debug calls within execution context defaults to 0.0
stream : sys.stdout, optional
valid output for a logging stream, by default sys.stdout
logger_formatter : PowertoolsFormatter, optional
custom logging formatter that implements PowertoolsFormatter
logger_handler : logging.Handler, optional
custom logging handler e.g. logging.FileHandler("file.log")
log_uncaught_exceptions : bool, by default False

logs uncaught exception using sys.excepthook

See: https://docs.python.org/3/library/sys.html#sys.excepthook

Parameters Propagated To Lambdapowertoolsformatter

datefmt: str, optional String directives (strftime) to format log timestamp using time, by default it uses 2021-05-03 11:47:12,494+0200. use_datetime_directive: bool, optional Interpret datefmt as a format string for datetime.datetime.strftime, rather than time.strftime.

See <https://docs.python.org/3/library/datetime.html#strftime-strptime-behavior> . This
also supports a custom %F directive for milliseconds.

use_rfc3339: bool, optional Whether to use a popular date format that complies with both RFC3339 and ISO8601. e.g., 2022-10-27T16:27:43.738+02:00. json_serializer : Callable, optional function to serialize obj to a JSON formatted str, by default json.dumps json_deserializer : Callable, optional function to deserialize str, bytes, bytearray containing a JSON document to a Python obj`, by default json.loads json_default : Callable, optional function to coerce unserializable values, by default str()

Only used when no custom formatter is set

utc : bool, optional set logging timestamp to UTC, by default False to continue to use local time as per stdlib log_record_order : list, optional set order of log keys when logging, by default ["level", "location", "message", "timestamp"]

Example

Setups structured logging in JSON for Lambda functions with explicit service name

>>> from aws_lambda_powertools import Logger
>>> logger = Logger(service="payment")
>>>
>>> def handler(event, context):
        logger.info("Hello")

Setups structured logging in JSON for Lambda functions using env vars

$ export POWERTOOLS_SERVICE_NAME="payment"
$ export POWERTOOLS_LOGGER_SAMPLE_RATE=0.01 # 1% debug sampling
>>> from aws_lambda_powertools import Logger
>>> logger = Logger()
>>>
>>> def handler(event, context):
        logger.info("Hello")

Append payment_id to previously setup logger

>>> from aws_lambda_powertools import Logger
>>> logger = Logger(service="payment")
>>>
>>> def handler(event, context):
        logger.append_keys(payment_id=event["payment_id"])
        logger.info("Hello")

Create child Logger using logging inheritance via child param

>>> # app.py
>>> import another_file
>>> from aws_lambda_powertools import Logger
>>> logger = Logger(service="payment")
>>>
>>> # another_file.py
>>> from aws_lambda_powertools import Logger
>>> logger = Logger(service="payment", child=True)

Logging in UTC timezone

>>> # app.py
>>> import logging
>>> from aws_lambda_powertools import Logger
>>>
>>> logger = Logger(service="payment", utc=True)

Brings message as the first key in log statements

>>> # app.py
>>> import logging
>>> from aws_lambda_powertools import Logger
>>>
>>> logger = Logger(service="payment", log_record_order=["message"])

Logging to a file instead of standard output for testing

>>> # app.py
>>> import logging
>>> from aws_lambda_powertools import Logger
>>>
>>> logger = Logger(service="payment", logger_handler=logging.FileHandler("log.json"))

Raises

InvalidLoggerSamplingRateError
When sampling rate provided is not a float

Instance variables

prop handlers : list[logging.Handler]
Expand source code
@property
def handlers(self) -> list[logging.Handler]:
    """List of registered logging handlers

    Notes
    -----

    Looking for the first configured handler? Use registered_handler property instead.
    """
    return self._logger.handlers

List of registered logging handlers

Notes

Looking for the first configured handler? Use registered_handler property instead.

prop log_level : int
Expand source code
@property
def log_level(self) -> int:
    return self._logger.level
prop name : str
Expand source code
@property
def name(self) -> str:
    return self._logger.name
prop registered_formatter : BasePowertoolsFormatter
Expand source code
@property
def registered_formatter(self) -> BasePowertoolsFormatter:
    """Convenience property to access the first logger formatter"""
    return self.registered_handler.formatter  # type: ignore[return-value]

Convenience property to access the first logger formatter

prop registered_handler : logging.Handler
Expand source code
@property
def registered_handler(self) -> logging.Handler:
    """Convenience property to access the first logger handler"""
    # We ignore mypy here because self.child encodes whether or not self._logger.parent is
    # None, mypy can't see this from context but we can
    handlers = self._logger.parent.handlers if self.child else self._logger.handlers  # type: ignore[union-attr]
    return handlers[0]

Convenience property to access the first logger handler

Methods

def addFilter(self, filter: logging._FilterType) ‑> None
Expand source code
def addFilter(self, filter: logging._FilterType) -> None:  # noqa: A002 # filter built-in usage
    return self._logger.addFilter(filter)
def addHandler(self, handler: logging.Handler) ‑> None
Expand source code
def addHandler(self, handler: logging.Handler) -> None:
    return self._logger.addHandler(handler)
def append_context_keys(self, **additional_keys: Any) ‑> Generator[None, None, None]
Expand source code
@contextmanager
def append_context_keys(self, **additional_keys: Any) -> Generator[None, None, None]:
    
""" Context manager to temporarily add logging keys. Parameters: ----------- **keys: Any Key-value pairs to include in the log context during the lifespan of the context manager. Example: -------- >>> logger = Logger(service="example_service") >>> with logger.append_context_keys(user_id="123", operation="process"): >>> logger.info("Log with context") >>> logger.info("Log without context") """
with self.registered_formatter.append_context_keys(**additional_keys): yield

Context manager to temporarily add logging keys.

Parameters:

**keys: Any Key-value pairs to include in the log context during the lifespan of the context manager.

Example:

>>> logger = Logger(service="example_service")
>>> with logger.append_context_keys(user_id="123", operation="process"):
>>>     logger.info("Log with context")
>>> logger.info("Log without context")
def append_keys(self, **additional_keys: object) ‑> None
Expand source code
def append_keys(self, **additional_keys: object) -> None:
    self.registered_formatter.append_keys(**additional_keys)
def critical(self,
msg: object,
*args: object,
exc_info: logging._ExcInfoType = None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Mapping[str, object] | None = None,
**kwargs: object) ‑> None
Expand source code
def critical(
    self,
    msg: object,
    *args: object,
    exc_info: logging._ExcInfoType = None,
    stack_info: bool = False,
    stacklevel: int = 2,
    extra: Mapping[str, object] | None = None,
    **kwargs: object,
) -> None:
    extra = extra or {}
    extra = {**extra, **kwargs}

    return self._logger.critical(
        msg,
        *args,
        exc_info=exc_info,
        stack_info=stack_info,
        stacklevel=stacklevel,
        extra=extra,
    )
def debug(self,
msg: object,
*args: object,
exc_info: logging._ExcInfoType = None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Mapping[str, object] | None = None,
**kwargs: object) ‑> None
Expand source code
def debug(
    self,
    msg: object,
    *args: object,
    exc_info: logging._ExcInfoType = None,
    stack_info: bool = False,
    stacklevel: int = 2,
    extra: Mapping[str, object] | None = None,
    **kwargs: object,
) -> None:
    extra = extra or {}
    extra = {**extra, **kwargs}

    return self._logger.debug(
        msg,
        *args,
        exc_info=exc_info,
        stack_info=stack_info,
        stacklevel=stacklevel,
        extra=extra,
    )
def error(self,
msg: object,
*args: object,
exc_info: logging._ExcInfoType = None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Mapping[str, object] | None = None,
**kwargs: object) ‑> None
Expand source code
def error(
    self,
    msg: object,
    *args: object,
    exc_info: logging._ExcInfoType = None,
    stack_info: bool = False,
    stacklevel: int = 2,
    extra: Mapping[str, object] | None = None,
    **kwargs: object,
) -> None:
    extra = extra or {}
    extra = {**extra, **kwargs}

    return self._logger.error(
        msg,
        *args,
        exc_info=exc_info,
        stack_info=stack_info,
        stacklevel=stacklevel,
        extra=extra,
    )
def exception(self,
msg: object,
*args: object,
exc_info: logging._ExcInfoType = True,
stack_info: bool = False,
stacklevel: int = 2,
extra: Mapping[str, object] | None = None,
**kwargs: object) ‑> None
Expand source code
def exception(
    self,
    msg: object,
    *args: object,
    exc_info: logging._ExcInfoType = True,
    stack_info: bool = False,
    stacklevel: int = 2,
    extra: Mapping[str, object] | None = None,
    **kwargs: object,
) -> None:
    extra = extra or {}
    extra = {**extra, **kwargs}

    return self._logger.exception(
        msg,
        *args,
        exc_info=exc_info,
        stack_info=stack_info,
        stacklevel=stacklevel,
        extra=extra,
    )
def get_correlation_id(self) ‑> str | None
Expand source code
def get_correlation_id(self) -> str | None:
    """Gets the correlation_id in the logging json

    Returns
    -------
    str, optional
        Value for the correlation id
    """
    if isinstance(self.registered_formatter, LambdaPowertoolsFormatter):
        return self.registered_formatter.log_format.get("correlation_id")
    return None

Gets the correlation_id in the logging json

Returns

str, optional
Value for the correlation id
def get_current_keys(self) ‑> dict[str, typing.Any]
Expand source code
def get_current_keys(self) -> dict[str, Any]:
    return self.registered_formatter.get_current_keys()
def info(self,
msg: object,
*args: object,
exc_info: logging._ExcInfoType = None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Mapping[str, object] | None = None,
**kwargs: object) ‑> None
Expand source code
def info(
    self,
    msg: object,
    *args: object,
    exc_info: logging._ExcInfoType = None,
    stack_info: bool = False,
    stacklevel: int = 2,
    extra: Mapping[str, object] | None = None,
    **kwargs: object,
) -> None:
    extra = extra or {}
    extra = {**extra, **kwargs}

    return self._logger.info(
        msg,
        *args,
        exc_info=exc_info,
        stack_info=stack_info,
        stacklevel=stacklevel,
        extra=extra,
    )
def inject_lambda_context(self,
lambda_handler: AnyCallableT | None = None,
log_event: bool | None = None,
correlation_id_path: str | None = None,
clear_state: bool | None = False) ‑> Any
Expand source code
def inject_lambda_context(
    self,
    lambda_handler: AnyCallableT | None = None,
    log_event: bool | None = None,
    correlation_id_path: str | None = None,
    clear_state: bool | None = False,
) -> Any:
    
"""Decorator to capture Lambda contextual info and inject into logger Parameters ---------- clear_state : bool, optional Instructs logger to remove any custom keys previously added lambda_handler : Callable Method to inject the lambda context log_event : bool, optional Instructs logger to log Lambda Event, by default False correlation_id_path: str, optional Optional JMESPath for the correlation_id Environment variables --------------------- POWERTOOLS_LOGGER_LOG_EVENT : str instruct logger to log Lambda Event (e.g. `"true", "True", "TRUE"`) Example ------- **Captures Lambda contextual runtime info (e.g memory, arn, req_id)** from aws_lambda_powertools import Logger logger = Logger(service="payment") @logger.inject_lambda_context def handler(event, context): logger.info("Hello") **Captures Lambda contextual runtime info and logs incoming request** from aws_lambda_powertools import Logger logger = Logger(service="payment") @logger.inject_lambda_context(log_event=True) def handler(event, context): logger.info("Hello") Returns ------- decorate : Callable Decorated lambda handler """
# If handler is None we've been called with parameters # Return a partial function with args filled if lambda_handler is None: logger.debug("Decorator called with parameters") return functools.partial( self.inject_lambda_context, log_event=log_event, correlation_id_path=correlation_id_path, clear_state=clear_state, ) log_event = resolve_truthy_env_var_choice( env=os.getenv(constants.LOGGER_LOG_EVENT_ENV, "false"), choice=log_event, ) @functools.wraps(lambda_handler) def decorate(event, context, *args, **kwargs): lambda_context = build_lambda_context_model(context) cold_start = _is_cold_start() if clear_state: self.structure_logs(cold_start=cold_start, **lambda_context.__dict__) else: self.append_keys(cold_start=cold_start, **lambda_context.__dict__) if correlation_id_path: self.set_correlation_id( jmespath_utils.query(envelope=correlation_id_path, data=event), ) if log_event: logger.debug("Event received") self.info(extract_event_from_common_models(event)) return lambda_handler(event, context, *args, **kwargs) return decorate

Decorator to capture Lambda contextual info and inject into logger

Parameters

clear_state : bool, optional
Instructs logger to remove any custom keys previously added
lambda_handler : Callable
Method to inject the lambda context
log_event : bool, optional
Instructs logger to log Lambda Event, by default False
correlation_id_path : str, optional
Optional JMESPath for the correlation_id

Environment Variables

POWERTOOLS_LOGGER_LOG_EVENT : str instruct logger to log Lambda Event (e.g. "true", "True", "TRUE")

Example

Captures Lambda contextual runtime info (e.g memory, arn, req_id)

from aws_lambda_powertools import Logger

logger = Logger(service="payment")

@logger.inject_lambda_context
def handler(event, context):
    logger.info("Hello")

Captures Lambda contextual runtime info and logs incoming request

from aws_lambda_powertools import Logger

logger = Logger(service="payment")

@logger.inject_lambda_context(log_event=True)
def handler(event, context):
    logger.info("Hello")

Returns

decorate : Callable
Decorated lambda handler
def removeFilter(self, filter: logging._FilterType) ‑> None
Expand source code
def removeFilter(self, filter: logging._FilterType) -> None:  # noqa: A002 # filter built-in usage
    return self._logger.removeFilter(filter)
def remove_keys(self, keys: Iterable[str]) ‑> None
Expand source code
def remove_keys(self, keys: Iterable[str]) -> None:
    self.registered_formatter.remove_keys(keys)
def setLevel(self, level: str | int | None) ‑> None
Expand source code
def setLevel(self, level: str | int | None) -> None:
    return self._logger.setLevel(self._determine_log_level(level))
def set_correlation_id(self, value: str | None) ‑> None
Expand source code
def set_correlation_id(self, value: str | None) -> None:
    """Sets the correlation_id in the logging json

    Parameters
    ----------
    value : str, optional
        Value for the correlation id. None will remove the correlation_id
    """
    self.append_keys(correlation_id=value)

Sets the correlation_id in the logging json

Parameters

value : str, optional
Value for the correlation id. None will remove the correlation_id
def structure_logs(self, append: bool = False, formatter_options: dict | None = None, **keys) ‑> None
Expand source code
def structure_logs(self, append: bool = False, formatter_options: dict | None = None, **keys) -> None:
    
"""Sets logging formatting to JSON. Optionally, it can append keyword arguments to an existing logger, so it is available across future log statements. Last keyword argument and value wins if duplicated. Parameters ---------- append : bool, optional append keys provided to logger formatter, by default False formatter_options : dict, optional LambdaPowertoolsFormatter options to be propagated, by default {} """
formatter_options = formatter_options or {} # There are 3 operational modes for this method ## 1. Register a Powertools for AWS Lambda (Python) Formatter for the first time ## 2. Append new keys to the current logger formatter; deprecated in favour of append_keys ## 3. Add new keys and discard existing to the registered formatter # Mode 1 log_keys = {**self._default_log_keys, **keys} is_logger_preconfigured = getattr(self._logger, LOGGER_ATTRIBUTE_PRECONFIGURED, False) if not is_logger_preconfigured: formatter = self.logger_formatter or LambdaPowertoolsFormatter(**formatter_options, **log_keys) self.registered_handler.setFormatter(formatter) # when using a custom Powertools for AWS Lambda (Python) Formatter # standard and custom keys that are not Powertools for AWS Lambda (Python) Formatter parameters # should be appended and custom keys that might happen to be Powertools for AWS Lambda (Python) # Formatter parameters should be discarded this prevents adding them as custom keys, for example, # `json_default=<callable>` see https://github.com/aws-powertools/powertools-lambda-python/issues/1263 custom_keys = {k: v for k, v in log_keys.items() if k not in RESERVED_FORMATTER_CUSTOM_KEYS} return self.registered_formatter.append_keys(**custom_keys) # Mode 2 (legacy) if append: # Maintenance: Add deprecation warning for major version return self.append_keys(**keys) # Mode 3 self.registered_formatter.clear_state() self.registered_formatter.thread_safe_clear_keys() self.registered_formatter.append_keys(**log_keys)

Sets logging formatting to JSON.

Optionally, it can append keyword arguments to an existing logger, so it is available across future log statements.

Last keyword argument and value wins if duplicated.

Parameters

append : bool, optional
append keys provided to logger formatter, by default False
formatter_options : dict, optional
LambdaPowertoolsFormatter options to be propagated, by default {}
def thread_safe_append_keys(self, **additional_keys: object) ‑> None
Expand source code
def thread_safe_append_keys(self, **additional_keys: object) -> None:
    # Append additional key-value pairs to the context safely in a thread-safe manner.
    self.registered_formatter.thread_safe_append_keys(**additional_keys)
def thread_safe_clear_keys(self) ‑> None
Expand source code
def thread_safe_clear_keys(self) -> None:
    # Clear all keys from the context safely in a thread-safe manner.
    self.registered_formatter.thread_safe_clear_keys()
def thread_safe_get_current_keys(self) ‑> dict[str, typing.Any]
Expand source code
def thread_safe_get_current_keys(self) -> dict[str, Any]:
    # Retrieve the current context keys safely in a thread-safe manner.
    return self.registered_formatter.thread_safe_get_current_keys()
def thread_safe_remove_keys(self, keys: Iterable[str]) ‑> None
Expand source code
def thread_safe_remove_keys(self, keys: Iterable[str]) -> None:
    # Remove specified keys from the context safely in a thread-safe manner.
    self.registered_formatter.thread_safe_remove_keys(keys)
def warning(self,
msg: object,
*args: object,
exc_info: logging._ExcInfoType = None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Mapping[str, object] | None = None,
**kwargs: object) ‑> None
Expand source code
def warning(
    self,
    msg: object,
    *args: object,
    exc_info: logging._ExcInfoType = None,
    stack_info: bool = False,
    stacklevel: int = 2,
    extra: Mapping[str, object] | None = None,
    **kwargs: object,
) -> None:
    extra = extra or {}
    extra = {**extra, **kwargs}

    return self._logger.warning(
        msg,
        *args,
        exc_info=exc_info,
        stack_info=stack_info,
        stacklevel=stacklevel,
        extra=extra,
    )