Fix comments

Author: wangzlei

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/aws_opentelemetry_configurator.py

@@ -122,7 +122,14 @@ class OtlpLogHeaderSetting(NamedTuple):
     log_group: Optional[str]
     log_stream: Optional[str]
     namespace: Optional[str]
-    is_valid: bool
+
+    def is_valid(self) -> bool:
+        """Check if the log header setting is valid by ensuring both log_group and log_stream are present."""
+        return self.log_group is not None and self.log_stream is not None
+
+
+# Singleton cache for OtlpLogHeaderSetting
+_otlp_log_header_setting_cache: Optional[OtlpLogHeaderSetting] = None
 
 
 class AwsOpenTelemetryConfigurator(_OTelSDKConfigurator):
@@ -440,7 +447,7 @@ def _customize_logs_exporter(log_exporter: LogExporter) -> LogExporter:
 
         if isinstance(log_exporter, OTLPLogExporter):
 
-            if _validate_and_fetch_logs_header().is_valid:
+            if _fetch_logs_header().is_valid():
                 endpoint, region = _extract_endpoint_and_region_from_otlp_endpoint(logs_endpoint)
                 # Setting default compression mode to Gzip as this is the behavior in upstream's
                 # collector otlp http exporter:
@@ -627,9 +634,12 @@ def _extract_endpoint_and_region_from_otlp_endpoint(endpoint: str):
     return endpoint, region
 
 
-def _validate_and_fetch_logs_header() -> OtlpLogHeaderSetting:
-    """Checks if x-aws-log-group and x-aws-log-stream are present in the headers in order to send logs to
-    AWS OTLP Logs endpoint."""
+def _fetch_logs_header() -> OtlpLogHeaderSetting:
+    """Returns the OTLP log header setting as a singleton instance."""
+    global _otlp_log_header_setting_cache  # pylint: disable=global-statement
+
+    if _otlp_log_header_setting_cache is not None:
+        return _otlp_log_header_setting_cache
 
     logs_headers = os.environ.get(OTEL_EXPORTER_OTLP_LOGS_HEADERS)
 
@@ -639,7 +649,8 @@ def _validate_and_fetch_logs_header() -> OtlpLogHeaderSetting:
                 "Improper configuration: Please configure the environment variable OTEL_EXPORTER_OTLP_LOGS_HEADERS "
                 "to include x-aws-log-group and x-aws-log-stream"
             )
-        return OtlpLogHeaderSetting(None, None, None, False)
+        _otlp_log_header_setting_cache = OtlpLogHeaderSetting(None, None, None)
+        return _otlp_log_header_setting_cache
 
     log_group = None
     log_stream = None
@@ -657,9 +668,14 @@ def _validate_and_fetch_logs_header() -> OtlpLogHeaderSetting:
             elif key == AWS_EMF_METRICS_NAMESPACE and value:
                 namespace = value
 
-    is_valid = log_group is not None and log_stream is not None
+    _otlp_log_header_setting_cache = OtlpLogHeaderSetting(log_group, log_stream, namespace)
+    return _otlp_log_header_setting_cache
 
-    return OtlpLogHeaderSetting(log_group, log_stream, namespace, is_valid)
+
+def _clear_logs_header_cache():
+    """Clear the singleton cache for OtlpLogHeaderSetting. Used primarily for testing."""
+    global _otlp_log_header_setting_cache  # pylint: disable=global-statement
+    _otlp_log_header_setting_cache = None
 
 
 def _get_metric_export_interval():
@@ -772,26 +788,26 @@ def _check_emf_exporter_enabled() -> bool:
 
     return True
 
+
 def _create_emf_exporter():
     """
     Create the appropriate EMF exporter based on the environment and configuration.
 
+    Returns:
+        ConsoleEmfExporter for Lambda without log headers log group and stream
+        AwsCloudWatchEmfExporter for other cases (when conditions are met)
+        None if CloudWatch exporter cannot be created
     """
-    log_header_setting = _validate_and_fetch_logs_header()
-    
-    if _is_lambda_environment() and not log_header_setting.is_valid:
+    try:
+        log_header_setting = _fetch_logs_header()
+
         # Lambda without valid logs http headers - use Console EMF exporter
-        from amazon.opentelemetry.distro.exporter.aws.metrics.console_emf_exporter import (
-            ConsoleEmfExporter,
-        )
-        return ConsoleEmfExporter(namespace=log_header_setting.namespace)
-    else:
-        # Non-Lambda environment - use CloudWatch EMF exporter
-        return _create_cloudwatch_emf_exporter()
+        if _is_lambda_environment() and not log_header_setting.is_valid():
+            # pylint: disable=import-outside-toplevel
+            from amazon.opentelemetry.distro.exporter.aws.metrics.console_emf_exporter import ConsoleEmfExporter
+            return ConsoleEmfExporter(namespace=log_header_setting.namespace)
 
-def _create_cloudwatch_emf_exporter():
-    """Create and configure the CloudWatch EMF exporter."""
-    try:
+        # For non-Lambda environment or Lambda with valid headers - use CloudWatch EMF exporter
         session = get_aws_session()
         # Check if botocore is available before importing the EMF exporter
         if not session:
@@ -803,9 +819,7 @@ def _create_cloudwatch_emf_exporter():
             AwsCloudWatchEmfExporter,
         )
 
-        log_header_setting = _validate_and_fetch_logs_header()
-
-        if not log_header_setting.is_valid:
+        if not log_header_setting.is_valid():
             return None
 
         return AwsCloudWatchEmfExporter(

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/exporter/aws/metrics/aws_cloudwatch_emf_exporter.py

@@ -57,7 +57,7 @@ def __init__(
             log_group_name=log_group_name, log_stream_name=log_stream_name, aws_region=aws_region, **kwargs
         )
 
-    def _send_log_event(self, log_event: Dict[str, Any]):
+    def _export(self, log_event: Dict[str, Any]):
         """
         Send a log event to CloudWatch Logs using the log client.
 

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/exporter/aws/metrics/base_emf_exporter.py

@@ -66,7 +66,7 @@ class BaseEmfExporter(MetricExporter, ABC):
     Base class for OpenTelemetry metrics exporters that convert to CloudWatch EMF format.
 
     This class contains all the common logic for converting OTel metrics into CloudWatch EMF logs.
-    Subclasses need to implement the _send_log_event method to define where the EMF logs are sent.
+    Subclasses need to implement the _export method to define where the EMF logs are sent.
 
     https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/CloudWatch_Embedded_Metric_Format_Specification.html
 
@@ -504,7 +504,7 @@ def _create_emf_log(
         return emf_log
 
     @abstractmethod
-    def _send_log_event(self, log_event: Dict[str, Any]):
+    def _export(self, log_event: Dict[str, Any]):
         """
         Send a log event to the destination (CloudWatch Logs, console, etc.).
 
@@ -513,7 +513,6 @@ def _send_log_event(self, log_event: Dict[str, Any]):
         Args:
             log_event: The log event to send
         """
-        pass
 
     # pylint: disable=too-many-nested-blocks,unused-argument,too-many-branches
     def export(
@@ -580,7 +579,7 @@ def export(
                             len(metric_records),
                             timestamp_ms,
                         )
-                        self._send_log_event(
+                        self._export(
                             {
                                 "message": json.dumps(
                                     self._create_emf_log(metric_records, resource_metrics.resource, timestamp_ms)

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/exporter/aws/metrics/console_emf_exporter.py

@@ -4,7 +4,6 @@
 # pylint: disable=no-self-use
 
 import logging
-import sys
 from typing import Any, Dict, Optional
 
 from opentelemetry.sdk.metrics.export import AggregationTemporality
@@ -47,17 +46,17 @@ def __init__(
             namespace = "default"
         super().__init__(namespace, preferred_temporality, preferred_aggregation)
 
-    def _send_log_event(self, log_event: Dict[str, Any]) -> None:
+    def _export(self, log_event: Dict[str, Any]) -> None:
         """
-        Send a log event to stdout for console output.
+        Send a log event message to stdout for console output.
 
         This method writes the EMF log message to stdout, making it easy to
         capture and redirect the output for processing or debugging purposes.
 
         Args:
             log_event: The log event dictionary containing 'message' and 'timestamp'
                       keys, where 'message' is the JSON-serialized EMF log
-        
+
         Raises:
             No exceptions are raised - errors are logged and handled gracefully
         """
@@ -68,10 +67,8 @@ def _send_log_event(self, log_event: Dict[str, Any]) -> None:
                 print(message, flush=True)
             else:
                 logger.warning("Empty message in log event: %s", log_event)
-        except (KeyError, TypeError) as e:
-            logger.error("Invalid log event format: %s. Error: %s", log_event, e)
-        except Exception as e:
-            logger.error("Failed to write EMF log to console: %s", e)
+        except Exception as error:  # pylint: disable=broad-exception-caught
+            logger.error("Failed to write EMF log to console. Log event: %s. Error: %s", log_event, error)
 
     def force_flush(self, timeout_millis: int = 10000) -> bool:
         """

aws-opentelemetry-distro/tests/amazon/opentelemetry/distro/exporter/aws/metrics/test_console_emf_exporter.py

@@ -16,30 +16,34 @@ def test_namespace_initialization(self):
         # Test default namespace
         exporter = ConsoleEmfExporter()
         self.assertEqual(exporter.namespace, "default")
-        
+
         # Test custom namespace
         exporter = ConsoleEmfExporter(namespace="CustomNamespace")
         self.assertEqual(exporter.namespace, "CustomNamespace")
-        
+
         # Test None namespace (should default to 'default')
         exporter = ConsoleEmfExporter(namespace=None)
         self.assertEqual(exporter.namespace, "default")
 
     def test_send_log_event(self):
         """Test that log events are properly sent to console output."""
         exporter = ConsoleEmfExporter()
-        
+
         # Create a simple log event with EMF-formatted message
-        test_message = '{"_aws":{"Timestamp":1640995200000,"CloudWatchMetrics":[{"Namespace":"TestNamespace","Dimensions":[["Service"]],"Metrics":[{"Name":"TestMetric","Unit":"Count"}]}]},"Service":"test-service","TestMetric":42}'
+        test_message = (
+            '{"_aws":{"Timestamp":1640995200000,"CloudWatchMetrics":[{"Namespace":"TestNamespace",'
+            '"Dimensions":[["Service"]],"Metrics":[{"Name":"TestMetric","Unit":"Count"}]}]},'
+            '"Service":"test-service","TestMetric":42}'
+        )
         log_event = {
             "message": test_message,
             "timestamp": 1640995200000
         }
-        
+
         # Capture stdout to verify the output
         with patch('sys.stdout', new_callable=StringIO) as mock_stdout:
-            exporter._send_log_event(log_event)
-            
+            exporter._export(log_event)
+
         # Verify the message was printed to stdout
         captured_output = mock_stdout.getvalue().strip()
         self.assertEqual(captured_output, test_message)