Merge pull request #14 from kbakk/custom_log_format

Custom log format

example/custom_log_format.py

@@ -0,0 +1,74 @@
+# This example shows how the logger can be set up to use a custom JSON format.
+import logging
+import json
+import traceback
+from datetime import datetime
+import copy
+import json_logging
+import sys
+
+json_logging.ENABLE_JSON_LOGGING = True
+
+
+def extra(**kw):
+    '''Add the required nested props layer'''
+    return {'extra': {'props': kw}}
+
+
+class CustomJSONLog(logging.Formatter):
+    """
+    Customized logger
+    """
+    python_log_prefix = 'python.'
+    def get_exc_fields(self, record):
+        if record.exc_info:
+            exc_info = self.format_exception(record.exc_info)
+        else:
+            exc_info = record.exc_text
+        return {f'{self.python_log_prefix}exc_info': exc_info}
+
+    @classmethod
+    def format_exception(cls, exc_info):
+        return ''.join(traceback.format_exception(*exc_info)) if exc_info else ''
+
+    def format(self, record):
+        json_log_object = {"@timestamp": datetime.utcnow().isoformat(),
+                           "level": record.levelname,
+                           "message": record.getMessage(),
+                           "caller": record.filename + '::' + record.funcName
+                           }
+        json_log_object['data'] = {
+            f'{self.python_log_prefix}logger_name': record.name,
+            f'{self.python_log_prefix}module': record.module,
+            f'{self.python_log_prefix}funcName': record.funcName,
+            f'{self.python_log_prefix}filename': record.filename,
+            f'{self.python_log_prefix}lineno': record.lineno,
+            f'{self.python_log_prefix}thread': f'{record.threadName}[{record.thread}]',
+            f'{self.python_log_prefix}pid': record.process
+        }
+        if hasattr(record, 'props'):
+            json_log_object['data'].update(record.props)
+
+        if record.exc_info or record.exc_text:
+            json_log_object['data'].update(self.get_exc_fields(record))
+
+        return json.dumps(json_log_object)
+
+
+def logger_init():
+    json_logging.init(custom_formatter=CustomJSONLog)
+
+# You would normally import logger_init and setup the logger in your main module - e.g.
+# main.py
+
+logger_init()
+
+logger = logging.getLogger(__name__)
+logger.setLevel(logging.DEBUG)
+logger.addHandler(logging.StreamHandler(sys.stderr))
+
+logger.info('Starting')
+try:
+    1/0
+except: # noqa pylint: disable=bare-except
+    logger.exception('You can\t divide by zero')

json_logging/__init__.py

@@ -95,12 +95,15 @@ def config_root_logger():
                 "logging.basicConfig() or logging.getLogger('root')")
 
 
-def init(framework_name=None):
+def init(framework_name=None, custom_formatter=None):
     """
     Initialize JSON logging support, if no **framework_name** passed, logging will be initialized in non-web context.
     This is supposed to be called only one time.
 
+    If **custom_formatter** is passed, it will (in non-web context) use this formatter over the default.
+
     :param framework_name: type of framework logging should support.
+    :param custom_formatter: formatter to override default JSONLogFormatter.
     """
 
     global _current_framework
@@ -123,6 +126,10 @@ def init(framework_name=None):
             _current_framework['app_configurator']().config()
 
         formatter = JSONLogWebFormatter
+    elif custom_formatter:
+        if not issubclass(custom_formatter, logging.Formatter):
+            raise ValueError('custom_formatter is not subclass of logging.Formatter', custom_formatter)
+        formatter = custom_formatter
     else:
         formatter = JSONLogFormatter