Add OpenTelemetry LoggingHandler conditionally (#38549)

Author: lzchen

sdk/monitor/azure-monitor-opentelemetry/CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Features Added
 
+- Only add OpenTelemetry LoggingHandler if current logger does not have it
+    ([#38549](https://github.com/Azure/azure-sdk-for-python/pull/38549))
 - Distro to automatically configure event logger provider
     ([#38543](https://github.com/Azure/azure-sdk-for-python/pull/38543))
 

sdk/monitor/azure-monitor-opentelemetry/azure/monitor/opentelemetry/_configure.py

@@ -170,9 +170,13 @@ def _setup_logging(configurations: Dict[str, ConfigurationValue]):
     )
     logger_provider.add_log_record_processor(log_record_processor)
     set_logger_provider(logger_provider)
-    handler = LoggingHandler(logger_provider=logger_provider)
     logger_name: str = configurations[LOGGER_NAME_ARG]  # type: ignore
-    getLogger(logger_name).addHandler(handler)
+    logger = getLogger(logger_name)
+    # Only add OpenTelemetry LoggingHandler if logger does not already have the handler
+    # This is to prevent most duplicate logging telemetry
+    if not any(isinstance(handler, LoggingHandler) for handler in logger.handlers):
+        handler = LoggingHandler(logger_provider=logger_provider)
+        logger.addHandler(handler)
 
     # Setup EventLoggerProvider
     event_provider = EventLoggerProvider(logger_provider)

sdk/monitor/azure-monitor-opentelemetry/samples/logging/basic.py

@@ -29,12 +29,12 @@
 logger.warning("warning log")
 logger.error("error log")
 
-logger.info("info log")
-logger.warning("warning log")
-logger.error("error log")
+logger_child.info("Child: info log")
+logger_child.warning("Child: warning log")
+logger_child.error("Child: error log")
 
-logger_not_tracked.info("info log2")
-logger_not_tracked.warning("warning log2")
-logger_not_tracked.error("error log2")
+logger_not_tracked.info("Not tracked: info log")
+logger_not_tracked.warning("Not tracked: warning log")
+logger_not_tracked.error("Not tracked: error log")
 
 input()

sdk/monitor/azure-monitor-opentelemetry/tests/test_configure.py

@@ -14,6 +14,7 @@
 import unittest
 from unittest.mock import Mock, call, patch
 
+from opentelemetry.sdk._logs import LoggingHandler
 from opentelemetry.sdk.resources import Resource
 
 from azure.core.tracing.ext.opentelemetry_span import OpenTelemetrySpan
@@ -351,6 +352,7 @@ def test_setup_logging(
         logging_handler_init_mock = Mock()
         logging_handler_mock.return_value = logging_handler_init_mock
         logger_mock = Mock()
+        logger_mock.handlers = []
         get_logger_mock.return_value = logger_mock
 
         configurations = {
@@ -373,6 +375,59 @@ def test_setup_logging(
         elp_mock.assert_called_once_with(lp_init_mock)
         set_elp_mock.assert_called_once_with(elp_init_mock)
 
+    @patch(
+        "azure.monitor.opentelemetry._configure.getLogger",
+    )
+    @patch(
+        "azure.monitor.opentelemetry._configure.BatchLogRecordProcessor",
+    )
+    @patch(
+        "azure.monitor.opentelemetry._configure.AzureMonitorLogExporter",
+    )
+    @patch(
+        "azure.monitor.opentelemetry._configure.set_logger_provider",
+    )
+    @patch(
+        "azure.monitor.opentelemetry._configure.LoggerProvider",
+        autospec=True,
+    )
+    def test_setup_logging_duplicate_logger(
+        self,
+        lp_mock,
+        set_logger_provider_mock,
+        log_exporter_mock,
+        blrp_mock,
+        get_logger_mock,
+    ):
+        lp_init_mock = Mock()
+        lp_mock.return_value = lp_init_mock
+        log_exp_init_mock = Mock()
+        log_exporter_mock.return_value = log_exp_init_mock
+        blrp_init_mock = Mock()
+        blrp_mock.return_value = blrp_init_mock
+        logging_handler_init_mock = Mock(spec=LoggingHandler)
+        logger_mock = Mock()
+        logger_mock.handlers = [logging_handler_init_mock]
+        get_logger_mock.return_value = logger_mock
+
+        configurations = {
+            "connection_string": "test_cs",
+            "logger_name": "test",
+            "resource": TEST_RESOURCE,
+        }
+        _setup_logging(configurations)
+
+        lp_mock.assert_called_once_with(resource=TEST_RESOURCE)
+        set_logger_provider_mock.assert_called_once_with(lp_init_mock)
+        log_exporter_mock.assert_called_once_with(**configurations)
+        blrp_mock.assert_called_once_with(
+            log_exp_init_mock,
+        )
+        lp_init_mock.add_log_record_processor.assert_called_once_with(blrp_init_mock)
+        # logging_handler_mock.assert_not_called()
+        get_logger_mock.assert_called_once_with("test")
+        logger_mock.addHandler.assert_not_called()
+
     @patch(
         "azure.monitor.opentelemetry._configure.PeriodicExportingMetricReader",
     )