1- import copy
21import functools
2+ import inspect
33import logging
44import os
55import random
@@ -34,7 +34,7 @@ def _is_cold_start() -> bool:
3434 return cold_start
3535
3636
37- class Logger ( logging . Logger ) :
37+ class Logger :
3838 """Creates and setups a logger to format statements in JSON.
3939
4040 Includes service name and any additional key=value into logs
@@ -55,6 +55,8 @@ class Logger(logging.Logger):
5555 service name to be appended in logs, by default "service_undefined"
5656 level : str, optional
5757 logging.level, by default "INFO"
58+ child: bool, optional
59+ create a child Logger named <service>.<caller_file_name>, False by default
5860 sample_rate: float, optional
5961 sample rate for debug calls within execution context defaults to 0.0
6062 stream: sys.stdout, optional
@@ -80,7 +82,7 @@ class Logger(logging.Logger):
8082 >>> def handler(event, context):
8183 logger.info("Hello")
8284
83- **Append payment_id to previously setup structured log logger**
85+ **Append payment_id to previously setup logger**
8486
8587 >>> from aws_lambda_powertools import Logger
8688 >>> logger = Logger(service="payment")
@@ -89,18 +91,16 @@ class Logger(logging.Logger):
8991 logger.structure_logs(append=True, payment_id=event["payment_id"])
9092 logger.info("Hello")
9193
92- Parameters
93- ----------
94- logging : logging.Logger
95- Inherits Logger
96- service: str
97- name of the service to create the logger for, "service_undefined" by default
98- level: str, int
99- log level, INFO by default
100- sampling_rate: float
101- debug log sampling rate, 0.0 by default
102- stream: sys.stdout
103- log stream, stdout by default
94+ **Create child Logger using logging inheritance via child param**
95+
96+ >>> # app.py
97+ >>> import another_file
98+ >>> from aws_lambda_powertools import Logger
99+ >>> logger = Logger(service="payment")
100+ >>>
101+ >>> # another_file.py
102+ >>> from aws_lambda_powertools import Logger
103+ >>> logger = Logger(service="payment", child=True)
104104
105105 Raises
106106 ------
@@ -112,19 +112,72 @@ def __init__(
112112 self ,
113113 service : str = None ,
114114 level : Union [str , int ] = None ,
115+ child : bool = False ,
115116 sampling_rate : float = None ,
116117 stream : sys .stdout = None ,
117118 ** kwargs ,
118119 ):
119120 self .service = service or os .getenv ("POWERTOOLS_SERVICE_NAME" ) or "service_undefined"
120121 self .sampling_rate = sampling_rate or os .getenv ("POWERTOOLS_LOGGER_SAMPLE_RATE" ) or 0.0
121- self .log_level = level or os .getenv ("LOG_LEVEL" ) or logging .INFO
122- self .handler = logging .StreamHandler (stream ) if stream is not None else logging .StreamHandler (sys .stdout )
122+ self .log_level = self ._get_log_level (level )
123+ self .child = child
124+ self ._handler = logging .StreamHandler (stream ) if stream is not None else logging .StreamHandler (sys .stdout )
123125 self ._default_log_keys = {"service" : self .service , "sampling_rate" : self .sampling_rate }
124- self .log_keys = copy .copy (self ._default_log_keys )
125-
126- super ().__init__ (name = self .service , level = self .log_level )
127-
126+ self ._logger = self ._get_logger ()
127+
128+ self ._init_logger (** kwargs )
129+
130+ def __getattr__ (self , name ):
131+ # Proxy attributes not found to actual logger to support backward compatibility
132+ # https://github.com/awslabs/aws-lambda-powertools-python/issues/97
133+ return getattr (self ._logger , name )
134+
135+ def _get_log_level (self , level : str ):
136+ """ Returns preferred log level set by the customer in upper case """
137+ log_level : str = level or os .getenv ("LOG_LEVEL" )
138+ log_level = log_level .upper () if log_level is not None else logging .INFO
139+
140+ return log_level
141+
142+ def _get_logger (self ):
143+ """ Returns a Logger named {self.service}, or {self.service.filename} for child loggers"""
144+ logger_name = self .service
145+ if self .child :
146+ logger_name = f"{ self .service } { self ._get_caller_filename ()}
147+
148+ return logging .getLogger (logger_name )
149+
150+ def _get_caller_filename (self ):
151+ """ Return caller filename by finding the caller frame """
152+ # Current frame => _get_logger()
153+ # Previous frame => logger.py
154+ # Before previous frame => Caller
155+ frame = inspect .currentframe ()
156+ caller_frame = frame .f_back .f_back .f_back
157+ filename = caller_frame .f_globals ["__name__" ]
158+
159+ return filename
160+
161+ def _init_logger (self , ** kwargs ):
162+ """Configures new logger"""
163+
164+ # Skip configuration if it's a child logger to prevent
165+ # multiple handlers being attached as well as different sampling mechanisms
166+ # and multiple messages from being logged as handlers can be duplicated
167+ if not self .child :
168+ self ._configure_sampling ()
169+ self ._logger .setLevel (self .log_level )
170+ self ._logger .addHandler (self ._handler )
171+ self .structure_logs (** kwargs )
172+
173+ def _configure_sampling (self ):
174+ """Dynamically set log level based on sampling rate
175+
176+ Raises
177+ ------
178+ InvalidLoggerSamplingRateError
179+ When sampling rate provided is not a float
180+ """
128181 try :
129182 if self .sampling_rate and random .random () <= float (self .sampling_rate ):
130183 logger .debug ("Setting log level to Debug due to sampling rate" )
@@ -134,12 +187,8 @@ def __init__(
134187 f"Expected a float value ranging 0 to 1, but received { self .sampling_rate } # noqa E501
135188 )
136189
137- self .setLevel (self .log_level )
138- self .structure_logs (** kwargs )
139- self .addHandler (self .handler )
140-
141190 def inject_lambda_context (self , lambda_handler : Callable [[Dict , Any ], Any ] = None , log_event : bool = False ):
142- """Decorator to capture Lambda contextual info and inject into struct logging
191+ """Decorator to capture Lambda contextual info and inject into logger
143192
144193 Parameters
145194 ----------
@@ -216,21 +265,24 @@ def structure_logs(self, append: bool = False, **kwargs):
216265 append : bool, optional
217266 [description], by default False
218267 """
219- self .handler .setFormatter (JsonFormatter (** self ._default_log_keys , ** kwargs ))
220-
221- if append :
222- new_keys = {** self .log_keys , ** kwargs }
223- self .handler .setFormatter (JsonFormatter (** new_keys ))
224268
225- self .log_keys .update (** kwargs )
269+ # Child loggers don't have handlers attached, use its parent handlers
270+ handlers = self ._logger .parent .handlers if self .child else self ._logger .handlers
271+ for handler in handlers :
272+ if append :
273+ # Update existing formatter in an existing logger handler
274+ handler .formatter .update_formatter (** kwargs )
275+ else :
276+ # Set a new formatter for a logger handler
277+ handler .setFormatter (JsonFormatter (** self ._default_log_keys , ** kwargs ))
226278
227279
228280def set_package_logger (
229281 level : Union [str , int ] = logging .DEBUG , stream : sys .stdout = None , formatter : logging .Formatter = None
230282):
231283 """Set an additional stream handler, formatter, and log level for aws_lambda_powertools package logger.
232284
233- **Package log by default is supressed (NullHandler), this should only used for debugging.
285+ **Package log by default is suppressed (NullHandler), this should only used for debugging.
234286 This is separate from application Logger class utility**
235287
236288 Example
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