fix external logs

Author: leandrodamascena

aws_lambda_powertools/logging/buffer/handler.py

@@ -3,6 +3,8 @@
 import logging
 from typing import TYPE_CHECKING
 
+from aws_lambda_powertools.logging.buffer.functions import _check_minimum_buffer_log_level
+
 if TYPE_CHECKING:
     from aws_lambda_powertools.logging.buffer.cache import LoggerBufferCache
     from aws_lambda_powertools.logging.buffer.config import LoggerBufferConfig
@@ -15,7 +17,8 @@ class BufferingHandler(logging.Handler):
 
     The handler intercepts log records from external libraries and
     stores them in the source logger's buffer using the same tracer_id mechanism.
-    Logs are flushed when an error occurs or when explicitly requested.
+    Logs above the buffer verbosity threshold are emitted directly through the source logger.
+    Logs at or below the threshold are buffered and flushed together with application logs.
     """
 
     def __init__(
@@ -43,14 +46,23 @@ def __init__(
 
     def emit(self, record: logging.LogRecord) -> None:
         """
-        Buffer the log record by delegating to source logger's buffering logic.
-        Call source logger to add a structured record to the buffer.
+        Buffer or emit the log record based on the buffer verbosity threshold.
+
+        Logs above the configured buffer_at_verbosity are emitted directly
+        through the source logger. Logs at or below the threshold are buffered.
 
         Parameters
         ----------
         record : logging.LogRecord
             The log record from an external logger
         """
+        level_name = logging.getLevelName(record.levelno)
+
+        # If log level exceeds buffer threshold, emit directly through source logger
+        if _check_minimum_buffer_log_level(self.buffer_config.buffer_at_verbosity, level_name):
+            self.source_logger._logger.handle(record)
+            return
+
         self.source_logger._add_log_record_to_buffer(
             level=record.levelno,
             msg=record.getMessage(),

tests/functional/logger/required_dependencies/test_logger_utils.py

@@ -322,8 +322,9 @@ def test_copy_config_to_ext_loggers_but_preserve_log_levels(stdout, logger, log_
 
 def test_copy_config_with_buffering_uses_buffering_handler(stdout, logger, log_level):
     # GIVEN an external logger and Powertools logger with buffer_config
+    # Using buffer_at_verbosity="WARNING" so INFO logs are buffered (not emitted directly)
     ext_logger = logger()
-    buffer_config = LoggerBufferConfig(max_bytes=10240)
+    buffer_config = LoggerBufferConfig(max_bytes=10240, buffer_at_verbosity="WARNING")
     powertools_logger = Logger(
         service=service_name(),
         level=log_level.INFO.value,

tests/unit/logger/required_dependencies/test_logger_buffer_handler.py

@@ -32,9 +32,10 @@ def test_buffering_handler_init_stores_dependencies():
 
 def test_buffering_handler_emit_calls_add_log_record_to_buffer(monkeypatch):
     # GIVEN a real Logger with buffer and a BufferingHandler (tracer id set so records are buffered)
+    # Using buffer_at_verbosity="WARNING" so INFO logs are buffered (below threshold)
     monkeypatch.setenv(constants.XRAY_TRACE_ID_ENV, "1-67c39786-5908a82a246fb67f3089263f")
     stream = io.StringIO()
-    buffer_config = LoggerBufferConfig(max_bytes=10240)
+    buffer_config = LoggerBufferConfig(max_bytes=10240, buffer_at_verbosity="WARNING")
     source_logger = Logger(service="test2", buffer_config=buffer_config, stream=stream)
     handler = BufferingHandler(
         buffer_cache=source_logger._buffer_cache,
@@ -55,9 +56,44 @@ def test_buffering_handler_emit_calls_add_log_record_to_buffer(monkeypatch):
 
     # WHEN the handler emits the record and the buffer is flushed
     handler.emit(record)
-    source_logger.flush_buffer()
 
-    # THEN the buffered message appears in the logger output
+    # THEN the message is NOT in output yet (it's buffered)
+    assert "test arg" not in stream.getvalue()
+
+    # AND when buffer is flushed, the buffered message appears in the logger output
+    source_logger.flush_buffer()
     output = stream.getvalue()
     log_line = json.loads(output.strip())
     assert log_line["message"] == "test arg"
+
+
+def test_buffering_handler_emit_above_threshold_emits_directly(monkeypatch):
+    # GIVEN a real Logger with buffer_at_verbosity="DEBUG" (default)
+    # INFO logs should be emitted directly since INFO > DEBUG
+    monkeypatch.setenv(constants.XRAY_TRACE_ID_ENV, "1-67c39786-5908a82a246fb67f3089263f")
+    stream = io.StringIO()
+    buffer_config = LoggerBufferConfig(max_bytes=10240, buffer_at_verbosity="DEBUG")
+    source_logger = Logger(service="test3", buffer_config=buffer_config, stream=stream)
+    handler = BufferingHandler(
+        buffer_cache=source_logger._buffer_cache,
+        buffer_config=source_logger._buffer_config,
+        source_logger=source_logger,
+    )
+    record = logging.LogRecord(
+        name="external",
+        level=logging.INFO,
+        pathname="",
+        lineno=0,
+        msg="direct message",
+        args=(),
+        exc_info=None,
+        func=None,
+    )
+    record.stack_info = None
+
+    # WHEN the handler emits the record
+    handler.emit(record)
+
+    # THEN the message appears immediately (not buffered)
+    output = stream.getvalue()
+    assert "direct message" in output