from __future__ import annotations
import functools
import inspect
import logging
import os
import random
import sys
from typing import (
IO,
TYPE_CHECKING,
Any,
Callable,
Dict,
Iterable,
List,
Mapping,
Optional,
TypeVar,
Union,
overload,
)
import jmespath
from aws_lambda_powertools.logging import compat
from ..shared import constants
from ..shared.functions import (
extract_event_from_common_models,
resolve_env_var_choice,
resolve_truthy_env_var_choice,
)
from ..shared.types import AnyCallableT
from .exceptions import InvalidLoggerSamplingRateError
from .filters import SuppressFilter
from .formatter import (
RESERVED_FORMATTER_CUSTOM_KEYS,
BasePowertoolsFormatter,
LambdaPowertoolsFormatter,
)
from .lambda_context import build_lambda_context_model
logger = logging.getLogger(__name__)
is_cold_start = True
PowertoolsFormatter = TypeVar("PowertoolsFormatter", bound=BasePowertoolsFormatter)
def _is_cold_start() -> bool:
"""Verifies whether is cold start
Returns
-------
bool
cold start bool value
"""
cold_start = False
global is_cold_start
if is_cold_start:
cold_start = is_cold_start
is_cold_start = False
return cold_start
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
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: Optional[str] = None,
level: Union[str, int, None] = None,
child: bool = False,
sampling_rate: Optional[float] = None,
stream: Optional[IO[str]] = None,
logger_formatter: Optional[PowertoolsFormatter] = None,
logger_handler: Optional[logging.Handler] = None,
log_uncaught_exceptions: bool = False,
json_serializer: Optional[Callable[[Dict], str]] = None,
json_deserializer: Optional[Callable[[Union[Dict, str, bool, int, float]], str]] = None,
json_default: Optional[Callable[[Any], Any]] = None,
datefmt: Optional[str] = None,
use_datetime_directive: bool = False,
log_record_order: Optional[List[str]] = None,
utc: bool = False,
use_rfc3339: bool = False,
**kwargs,
):
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,
}
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:
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):
"""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: Optional[Dict] = None, log_level: Union[str, int, None] = None, **kwargs):
"""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, "init", False)
if self.child or is_logger_preconfigured:
return
self.setLevel(self._determine_log_level(log_level))
self._configure_sampling()
self.addHandler(self.logger_handler)
self.structure_logs(formatter_options=formatter_options, **kwargs)
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
self._logger.findCaller = compat.findCaller
# 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
def _configure_sampling(self):
"""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."
f"Please review POWERTOOLS_LOGGER_SAMPLE_RATE environment variable.",
)
@overload
def inject_lambda_context(
self,
lambda_handler: AnyCallableT,
log_event: Optional[bool] = None,
correlation_id_path: Optional[str] = None,
clear_state: Optional[bool] = False,
) -> AnyCallableT:
...
@overload
def inject_lambda_context(
self,
lambda_handler: None = None,
log_event: Optional[bool] = None,
correlation_id_path: Optional[str] = None,
clear_state: Optional[bool] = False,
) -> Callable[[AnyCallableT], AnyCallableT]:
...
def inject_lambda_context(
self,
lambda_handler: Optional[AnyCallableT] = None,
log_event: Optional[bool] = None,
correlation_id_path: Optional[str] = None,
clear_state: Optional[bool] = 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.search(correlation_id_path, 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,
exc_info=None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Optional[Mapping[str, object]] = None,
**kwargs,
):
extra = extra or {}
extra = {**extra, **kwargs}
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
if sys.version_info < (3, 8): # pragma: no cover
return self._logger.info(msg, *args, exc_info=exc_info, stack_info=stack_info, extra=extra)
return self._logger.info(
msg,
*args,
exc_info=exc_info,
stack_info=stack_info,
stacklevel=stacklevel,
extra=extra,
)
def error(
self,
msg: object,
*args,
exc_info=None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Optional[Mapping[str, object]] = None,
**kwargs,
):
extra = extra or {}
extra = {**extra, **kwargs}
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
if sys.version_info < (3, 8): # pragma: no cover
return self._logger.error(msg, *args, exc_info=exc_info, stack_info=stack_info, extra=extra)
return self._logger.error(
msg,
*args,
exc_info=exc_info,
stack_info=stack_info,
stacklevel=stacklevel,
extra=extra,
)
def exception(
self,
msg: object,
*args,
exc_info=True,
stack_info: bool = False,
stacklevel: int = 2,
extra: Optional[Mapping[str, object]] = None,
**kwargs,
):
extra = extra or {}
extra = {**extra, **kwargs}
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
if sys.version_info < (3, 8): # pragma: no cover
return self._logger.exception(msg, *args, exc_info=exc_info, stack_info=stack_info, extra=extra)
return self._logger.exception(
msg,
*args,
exc_info=exc_info,
stack_info=stack_info,
stacklevel=stacklevel,
extra=extra,
)
def critical(
self,
msg: object,
*args,
exc_info=None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Optional[Mapping[str, object]] = None,
**kwargs,
):
extra = extra or {}
extra = {**extra, **kwargs}
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
if sys.version_info < (3, 8): # pragma: no cover
return self._logger.critical(msg, *args, exc_info=exc_info, stack_info=stack_info, extra=extra)
return self._logger.critical(
msg,
*args,
exc_info=exc_info,
stack_info=stack_info,
stacklevel=stacklevel,
extra=extra,
)
def warning(
self,
msg: object,
*args,
exc_info=None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Optional[Mapping[str, object]] = None,
**kwargs,
):
extra = extra or {}
extra = {**extra, **kwargs}
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
if sys.version_info < (3, 8): # pragma: no cover
return self._logger.warning(msg, *args, exc_info=exc_info, stack_info=stack_info, extra=extra)
return self._logger.warning(
msg,
*args,
exc_info=exc_info,
stack_info=stack_info,
stacklevel=stacklevel,
extra=extra,
)
def debug(
self,
msg: object,
*args,
exc_info=None,
stack_info: bool = False,
stacklevel: int = 2,
extra: Optional[Mapping[str, object]] = None,
**kwargs,
):
extra = extra or {}
extra = {**extra, **kwargs}
# Maintenance: We can drop this upon Py3.7 EOL. It's a backport for "location" key to work
if sys.version_info < (3, 8): # pragma: no cover
return self._logger.debug(msg, *args, exc_info=exc_info, stack_info=stack_info, extra=extra)
return self._logger.debug(
msg,
*args,
exc_info=exc_info,
stack_info=stack_info,
stacklevel=stacklevel,
extra=extra,
)
def append_keys(self, **additional_keys):
self.registered_formatter.append_keys(**additional_keys)
def remove_keys(self, keys: Iterable[str]):
self.registered_formatter.remove_keys(keys)
def structure_logs(self, append: bool = False, formatter_options: Optional[Dict] = None, **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 {}
"""
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, "init", 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.append_keys(**log_keys)
def set_correlation_id(self, value: Optional[str]):
"""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) -> Optional[str]:
"""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: Union[str, int]) -> None:
return self._logger.setLevel(level)
def addHandler(self, handler: logging.Handler) -> None:
return self._logger.addHandler(handler)
@property
def registered_handler(self) -> logging.Handler:
"""Convenience property to access the first logger handler"""
handlers = self._logger.parent.handlers if self.child else self._logger.handlers
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
@staticmethod
def _determine_log_level(level: Union[str, int, None]) -> Union[str, int]:
"""Returns preferred log level set by the customer in upper case"""
if isinstance(level, int):
return level
log_level: Optional[str] = level or os.getenv("LOG_LEVEL")
if log_level is None:
return logging.INFO
return log_level.upper()
def set_package_logger(
level: Union[str, int] = logging.DEBUG,
stream: Optional[IO[str]] = None,
formatter: Optional[logging.Formatter] = 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)
def log_uncaught_exception_hook(exc_type, exc_value, exc_traceback, logger: Logger):
"""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
def _get_caller_filename():
"""Return caller filename by finding the caller frame"""
# Current frame => _get_logger()
# Previous frame => logger.py
# Before previous frame => Caller
frame = inspect.currentframe()
caller_frame = frame.f_back.f_back.f_back
return caller_frame.f_globals["__name__"]