fix(formatter): custom fields

src/bunyan_formatter/logger.py

@@ -2,21 +2,46 @@ import json
 import logging
 import socket
 import time
+import traceback
 from logging import Formatter, LogRecord
 from pathlib import Path
-from typing import ClassVar, Optional
+from typing import Any, Optional
+
+DEFAULT_FIELDS = {
+    "name",
+    "msg",
+    "args",
+    "levelname",
+    "levelno",
+    "pathname",
+    "filename",
+    "module",
+    "exc_info",
+    "exc_text",
+    "stack_info",
+    "lineno",
+    "funcName",
+    "created",
+    "msecs",
+    "relativeCreated",
+    "thread",
+    "threadName",
+    "processName",
+    "process",
+    "taskName",
+}
+
+LEVEL_MAP = {
+    logging.NOTSET: 10,
+    logging.DEBUG: 20,
+    logging.INFO: 30,
+    logging.WARNING: 40,
+    logging.ERROR: 50,
+    logging.CRITICAL: 60,
+}
 
 
 class BunyanFormatter(Formatter):
-    LEVEL_MAP: ClassVar[dict[int, int]] = {
-        logging.NOTSET: 10,
-        logging.DEBUG: 20,
-        logging.INFO: 30,
-        logging.WARNING: 40,
-        logging.ERROR: 50,
-        logging.CRITICAL: 60,
-    }
-
     def __init__(self, project_name: str, project_root: Path) -> None:
         super().__init__()
         self.project_name = project_name
@@ -24,8 +49,6 @@ class BunyanFormatter(Formatter):
         self.hostname = socket.gethostname()
 
     def format(self, record: LogRecord) -> str:
-        hostname = socket.gethostname()
-
         file_path = Path(record.pathname)
         try:
             relative_path = file_path.relative_to(self.project_root)
@@ -36,9 +59,9 @@ class BunyanFormatter(Formatter):
             "v": 0,
             "name": self.project_name,
             "msg": record.getMessage(),
-            "level": self.LEVEL_MAP.get(record.levelno, record.levelno),
+            "level": LEVEL_MAP.get(record.levelno, record.levelno),
             "levelname": record.levelname,
-            "hostname": hostname,
+            "hostname": self.hostname,
             "pid": record.process,
             "time": self.formatTime(record),
             "target": record.name,
@@ -46,6 +69,15 @@ class BunyanFormatter(Formatter):
             "file": str(relative_path),
         }
 
+        # Handle extra fields
+        extra_fields = {k: v for k, v in record.__dict__.items() if k not in DEFAULT_FIELDS}
+        if extra_fields:
+            log_entry["extra"] = extra_fields
+
+        # Handle exception information
+        if record.exc_info and all(record.exc_info):
+            log_entry["err"] = self._format_exception(record)
+
         return json.dumps(log_entry)
 
     def formatTime(self, record: LogRecord, datefmt: Optional[str] = None) -> str:  # noqa: N802
@@ -56,3 +88,30 @@ class BunyanFormatter(Formatter):
             t = time.strftime("%Y-%m-%dT%H:%M:%S", ct)
             s = f"{t}.{int(record.msecs):03d}Z"
         return s
+
+    def _format_exception(self, record: LogRecord) -> dict[str, Any]:
+        exc_info = record.exc_info
+
+        if exc_info is None or len(exc_info) != 3:
+            return {}
+
+        exc_type, exc_value, exc_traceback = exc_info
+
+        if exc_type is None or exc_value is None or exc_traceback is None:
+            return {}
+
+        stack = traceback.extract_tb(exc_traceback)
+
+        return {
+            "message": str(exc_value),
+            "name": getattr(exc_type, "__name__", "UnknownException"),
+            "stack": [
+                {
+                    "file": frame.filename,
+                    "line": frame.lineno,
+                    "function": frame.name,
+                    "text": frame.line.strip() if frame.line is not None else "",
+                }
+                for frame in stack
+            ],
+        }