fix: map Python CRITICAL log level to OTel FATAL severity text (#4365)

* 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

* Add CHANGELOG entry for CRITICAL -> FATAL severity text mapping

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

---------

Co-authored-by: Leighton Chen <lechen@microsoft.com>
Co-authored-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>

Author: 3 people

CHANGELOG.md

@@ -32,6 +32,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#4305](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4305))
 - Don't import module in unwrap if not already imported
   ([#4321](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4321))
+- `opentelemetry-instrumentation-logging`: Map Python `CRITICAL` log level to OTel `FATAL` severity text and `WARNING` to `WARN`
+  ([#4365](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4365))
 - `opentelemetry-instrumentation-logging`: Add recursion guard in LoggingHandler.emit to prevent deadlock
   ([#4302](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4302))
 - `opentelemetry-instrumentation-grpc`: Fix bidirectional streaming RPCs raising `AttributeError: 'generator' object has no attribute 'add_done_callback'`

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

@@ -188,10 +188,14 @@ 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_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
             )