fix: map Python CRITICAL log level to OTel FATAL severity text in contrib handler

The OTel specification defines the severity text for the highest severity
range as "FATAL", but the contrib logging handler was passing through
Python's native "CRITICAL" level name unchanged. This mirrors the fix
made in open-telemetry/opentelemetry-python#5011 for the SDK handler.

Related: open-telemetry/opentelemetry-python#4984

Author: Krishnachaitanyakc

instrumentation/opentelemetry-instrumentation-logging/src/opentelemetry/instrumentation/logging/handler.py

@@ -188,10 +188,16 @@ def _translate(self, record: logging.LogRecord) -> LogRecord:
             else:
                 body = record.getMessage()
 
-        # related to https://github.com/open-telemetry/opentelemetry-python/issues/3548
-        # Severity Text = WARN as defined in https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/data-model.md#displaying-severity.
-        level_name = (
-            "WARN" if record.levelname == "WARNING" else record.levelname
+        # Map Python log level names to OTel severity text as defined in
+        # https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/logs/data-model.md#displaying-severity
+        # Python "WARNING" -> OTel "WARN" (see open-telemetry/opentelemetry-python#3548)
+        # Python "CRITICAL" -> OTel "FATAL" (see open-telemetry/opentelemetry-python#4984)
+        _python_to_otel_severity_text = {
+            "WARNING": "WARN",
+            "CRITICAL": "FATAL",
+        }
+        level_name = _python_to_otel_severity_text.get(
+            record.levelname, record.levelname
         )
 
         return LogRecord(

instrumentation/opentelemetry-instrumentation-logging/tests/test_handler.py

@@ -357,7 +357,7 @@ def test_log_record_trace_correlation(self):
                     record.log_record.body,
                     "Critical message within span",
                 )
-                self.assertEqual(record.log_record.severity_text, "CRITICAL")
+                self.assertEqual(record.log_record.severity_text, "FATAL")
                 self.assertEqual(
                     record.log_record.severity_number,
                     SeverityNumber.FATAL,
@@ -390,7 +390,7 @@ def test_log_record_trace_correlation_deprecated(self):
             self.assertEqual(
                 record.log_record.body, "Critical message within span"
             )
-            self.assertEqual(record.log_record.severity_text, "CRITICAL")
+            self.assertEqual(record.log_record.severity_text, "FATAL")
             self.assertEqual(
                 record.log_record.severity_number, SeverityNumber.FATAL
             )