Add TRACE logging level for verbose payload logging across event writers

Author: oto-macenauer-absa

src/event_gate_lambda.py

@@ -43,6 +43,12 @@
 except ImportError:  # fallback when executed outside package context
     import writer_eventbridge, writer_kafka, writer_postgres  # type: ignore[no-redef]
 
+# Register custom TRACE level before using LOG_LEVEL env var
+try:
+    from .logging_levels import TRACE_LEVEL  # noqa: F401
+except Exception:  # pragma: no cover - defensive
+    TRACE_LEVEL = 5  # type: ignore
+
 # Import configuration directory symbols with explicit ImportError fallback
 try:
     from .conf_path import CONF_DIR, INVALID_CONF_ENV  # type: ignore[no-redef]

src/logging_levels.py

@@ -0,0 +1,21 @@
+"""Custom logging levels.
+
+Adds a TRACE level below DEBUG for very verbose payload logging.
+"""
+
+from __future__ import annotations
+import logging
+
+TRACE_LEVEL = 5
+
+# Register level name only once (idempotent)
+if not hasattr(logging, "TRACE"):
+    logging.addLevelName(TRACE_LEVEL, "TRACE")
+
+    def trace(self: logging.Logger, message: str, *args, **kws):  # type: ignore[override]
+        if self.isEnabledFor(TRACE_LEVEL):
+            self._log(TRACE_LEVEL, message, args, **kws)  # pylint: disable=protected-access
+
+    logging.Logger.trace = trace  # type: ignore[attr-defined]
+
+__all__ = ["TRACE_LEVEL"]

src/writer_eventbridge.py

@@ -26,6 +26,10 @@
 import boto3
 from botocore.exceptions import BotoCoreError, ClientError
 
+# Ensure TRACE level is registered
+from . import logging_levels  # noqa: F401
+from .logging_levels import TRACE_LEVEL
+
 STATE: Dict[str, Any] = {"logger": logging.getLogger(__name__), "event_bus_arn": "", "client": None}
 
 
@@ -68,6 +72,15 @@ def write(topic_name: str, message: Dict[str, Any]) -> Tuple[bool, Optional[str]
         logger.debug("EventBridge client not initialized - skipping")
         return True, None
 
+    # TRACE-level payload logging
+    if logger.isEnabledFor(TRACE_LEVEL):
+        try:
+            logger.trace(  # type: ignore[attr-defined]
+                "EventBridge payload topic=%s payload=%s", topic_name, json.dumps(message, separators=(",", ":"))
+            )
+        except Exception:  # pragma: no cover - defensive serialization guard
+            logger.trace("EventBridge payload topic=%s <unserializable>", topic_name)  # type: ignore[attr-defined]
+
     try:
         logger.debug("Sending to eventBridge %s", topic_name)
         response = client.put_events(

src/writer_kafka.py

@@ -26,6 +26,9 @@
 
 from confluent_kafka import Producer
 
+# Add TRACE level import
+from .logging_levels import TRACE_LEVEL  # type: ignore
+
 try:  # KafkaException may not exist in stubbed test module
     from confluent_kafka import KafkaException  # type: ignore
 except (ImportError, ModuleNotFoundError):  # pragma: no cover - fallback for test stub
@@ -91,6 +94,15 @@ def write(topic_name: str, message: Dict[str, Any]) -> Tuple[bool, Optional[str]
         logger.debug("Kafka producer not initialized - skipping")
         return True, None
 
+    # TRACE-level payload logging prior to produce
+    if logger.isEnabledFor(TRACE_LEVEL):
+        try:
+            logger.trace(  # type: ignore[attr-defined]
+                "Kafka payload topic=%s payload=%s", topic_name, json.dumps(message, separators=(",", ":"))
+            )
+        except Exception:  # pragma: no cover - defensive
+            logger.trace("Kafka payload topic=%s <unserializable>", topic_name)  # type: ignore[attr-defined]
+
     errors: list[Any] = []
     try:
         logger.debug("Sending to kafka %s", topic_name)

src/writer_postgres.py

@@ -31,6 +31,9 @@
 except ImportError:  # pragma: no cover - environment without psycopg2
     psycopg2 = None  # type: ignore
 
+# Ensure TRACE level is registered
+from .logging_levels import TRACE_LEVEL  # type: ignore
+
 # Define a unified psycopg2 error base for safe exception handling even if psycopg2 missing
 if psycopg2 is not None:  # type: ignore
     try:  # pragma: no cover - attribute presence depends on installed psycopg2 variant
@@ -271,6 +274,15 @@ def write(topic_name: str, message: Dict[str, Any]) -> Tuple[bool, Optional[str]
             _logger.debug("psycopg2 not available - skipping actual Postgres write")
             return True, None
 
+        # TRACE-level payload logging (only when we intend to write)
+        if _logger.isEnabledFor(TRACE_LEVEL):
+            try:
+                _logger.trace(  # type: ignore[attr-defined]
+                    "Postgres payload topic=%s payload=%s", topic_name, json.dumps(message, separators=(",", ":"))
+                )
+            except Exception:  # pragma: no cover - defensive
+                _logger.trace("Postgres payload topic=%s <unserializable>", topic_name)  # type: ignore[attr-defined]
+
         with psycopg2.connect(  # type: ignore[attr-defined]
             database=POSTGRES["database"],
             host=POSTGRES["host"],

tests/test_trace_logging.py

@@ -0,0 +1,86 @@
+import logging
+from unittest.mock import MagicMock
+
+from src.logging_levels import TRACE_LEVEL
+import src.writer_eventbridge as we
+import src.writer_kafka as wk
+import src.writer_postgres as wp
+
+
+def test_trace_eventbridge(caplog):
+    logger = logging.getLogger("trace.eventbridge")
+    logger.setLevel(TRACE_LEVEL)
+    we.STATE["logger"] = logger
+    we.STATE["event_bus_arn"] = "arn:aws:events:region:acct:event-bus/test"
+    mock_client = MagicMock()
+    mock_client.put_events.return_value = {"FailedEntryCount": 0, "Entries": []}
+    we.STATE["client"] = mock_client
+    caplog.set_level(TRACE_LEVEL)
+    ok, err = we.write("topic.eb", {"k": 1})
+    assert ok and err is None
+    assert any("EventBridge payload" in rec.message for rec in caplog.records)
+
+
+def test_trace_kafka(caplog):
+    class FakeProducer:
+        def produce(self, *a, **kw):
+            cb = kw.get("callback")
+            if cb:
+                cb(None, object())
+
+        def flush(self, *a, **kw):  # noqa: D401
+            return 0
+
+    logger = logging.getLogger("trace.kafka")
+    logger.setLevel(TRACE_LEVEL)
+    wk.STATE["logger"] = logger
+    wk.STATE["producer"] = FakeProducer()
+    caplog.set_level(TRACE_LEVEL)
+    ok, err = wk.write("topic.kf", {"k": 2})
+    assert ok and err is None
+    assert any("Kafka payload" in rec.message for rec in caplog.records)
+
+
+def test_trace_postgres(caplog, monkeypatch):
+    # Prepare dummy psycopg2 connection machinery
+    store = []
+
+    class DummyCursor:
+        def execute(self, sql, params):
+            store.append((sql, params))
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, exc_type, exc, tb):
+            return False
+
+    class DummyConnection:
+        def cursor(self):
+            return DummyCursor()
+
+        def commit(self):
+            pass
+
+        def __enter__(self):
+            return self
+
+        def __exit__(self, exc_type, exc, tb):
+            return False
+
+    class DummyPsycopg2:
+        def connect(self, **kwargs):  # noqa: D401
+            return DummyConnection()
+
+    monkeypatch.setattr(wp, "psycopg2", DummyPsycopg2())
+
+    logger = logging.getLogger("trace.postgres")
+    logger.setLevel(TRACE_LEVEL)
+    wp._logger = logger  # type: ignore
+    wp.POSTGRES = {"database": "db", "host": "h", "user": "u", "password": "p", "port": 5432}
+
+    caplog.set_level(TRACE_LEVEL)
+    message = {"event_id": "e", "tenant_id": "t", "source_app": "a", "environment": "dev", "timestamp": 1}
+    ok, err = wp.write("public.cps.za.test", message)
+    assert ok and err is None
+    assert any("Postgres payload" in rec.message for rec in caplog.records)