Formatter ABC to help clarify usage.

README.md

@@ -25,7 +25,7 @@ A logging handler that sends log messages to **(Grafana) Loki** in JSON format.
 * timeout (int, optional): Timeout interval in seconds to wait before flushing the buffer. Defaults to 10 seconds.
 * compressed (bool, optional): Whether to compress the log messages before sending them to Loki. Defaults to True.
 * loguru (bool, optional): Whether to use `LoguruFormatter`. Defaults to False.
-* default_formatter (logging.Formatter, optional): Formatter for the log records. If not provided,`LoggerFormatter` or `LoguruFormatter` will be used.
+* default_formatter (loki_logger_handler.formatters.LogFormatter, optional): Formatter for the log records. If not provided, `LoggerFormatter` or `LoguruFormatter` will be used.
 * enable_self_errors (bool, optional): Set to True to show Hanlder errors on console. Defaults to False
 ### Loki 3.0 
 * enable_structured_loki_metadata (bool, optional):  Whether to include structured loki_metadata in the logs. Defaults to False. Only supported for Loki 3.0 and above

loki_logger_handler/formatters/__init__.py

@@ -0,0 +1,18 @@
+import logging
+from abc import ABC, abstractmethod
+
+
+class LogFormatter(ABC):
+    @abstractmethod
+    def format(self, record):
+        # type: (logging.LogRecord) ->  dict | dict
+        """
+        Format a log record into a structured dictionary.
+
+        Args:
+            record (logging.LogRecord): The log record to format.
+
+        Returns:
+            (tuple): A tuple of dictionary representation of the log record and the extracted loki metadata
+        """
+        raise NotImplementedError

loki_logger_handler/formatters/logger_formatter.py

@@ -1,9 +1,11 @@
 import traceback
-import time
 
-class LoggerFormatter:
+from loki_logger_handler.formatters import LogFormatter
+
+
+class LoggerFormatter(LogFormatter):
     """
-    A custom formatter for log records that formats the log record into a structured dictionary.
+    A custom formatter for log records generated by the standard library logger, formatting the record into a structured dictionary.
     """
     LOG_RECORD_FIELDS = {
         "msg",
@@ -28,9 +30,6 @@ class LoggerFormatter:
         "exc_text",
     }
 
-    def __init__(self):
-        pass
-
     def format(self, record):
         """
         Format a log record into a structured dictionary.
@@ -39,7 +38,7 @@ def format(self, record):
             record (logging.LogRecord): The log record to format.
 
         Returns:
-            dict: A dictionary representation of the log record.
+            (tuple): A tuple of dictionary representation of the log record and the extracted loki metadata.
         """
 
         formatted = {

loki_logger_handler/formatters/loguru_formatter.py

@@ -1,14 +1,13 @@
 import traceback
 import sys
 
+from loki_logger_handler.formatters import LogFormatter
 
-class LoguruFormatter:
+
+class LoguruFormatter(LogFormatter):
     """
     A custom formatter for log records generated by Loguru, formatting the record into a structured dictionary.
     """
-    def __init__(self):
-        pass
-
     def format(self, record):
         """
         Format a Loguru log record into a structured dictionary.
@@ -17,7 +16,7 @@ def format(self, record):
             record (dict): The Loguru log record to format.
 
         Returns:
-            dict: A dictionary representation of the log record.
+            (tuple): A tuple of dictionary representation of the log record and the extracted loki metadata
         """
         # Convert timestamp to a standard format across Python versions
         timestamp = record.get("time")
@@ -65,7 +64,8 @@ def format(self, record):
 
         return formatted, loki_metadata
 
-    def add_exception_details(self, record, formatted):
+    @staticmethod
+    def add_exception_details(record, formatted):
         """
         Adds exception details to the formatted log record.
 

loki_logger_handler/loki_logger_handler.py

@@ -49,7 +49,7 @@ def __init__(
             message_in_json_format (bool): Whether to format log values as JSON.
             timeout (int, optional): Timeout interval for flushing logs. Defaults to 10 seconds.
             compressed (bool, optional): Whether to compress the logs using gzip. Defaults to True.
-            default_formatter (logging.Formatter, optional): Formatter for the log records. If not provided, LoggerFormatter or LoguruFormatter will be used.
+            default_formatter (loki_logger_handler.formatters.LogFormatter, optional): Formatter for the log records. If not provided, LoggerFormatter or LoguruFormatter will be used.
             enable_self_errors (bool, optional): Set to True to show Hanlder errors on console. Default False
             enable_structured_loki_metadata (bool, optional):  Whether to include structured loki_metadata in the logs. Defaults to False. Only supported for Loki 3.0 and above
             loki_metadata (dict, optional): Default loki_metadata values. Defaults to None. Only supported for Loki 3.0 and above