fix(py): Log to stderr not stdout

src/sentry/runner/initializer.py

@@ -3,6 +3,7 @@
 import importlib.metadata
 import logging
 import os
+import sys
 from typing import IO, Any
 
 import click
@@ -259,8 +260,15 @@ def configure_structlog() -> None:
 
         kwargs["processors"].append(JSONRenderer())
 
+    is_s4s = os.environ.get("CUSTOMER_ID") == "sentry4sentry"
+    if is_s4s:
+        kwargs["logger_factory"] = structlog.PrintLoggerFactory(sys.stderr)
+
     structlog.configure(**kwargs)
 
+    if is_s4s:
+        logging.info("Writing logs to stderr. Expected only in s4s")
+
     lvl = os.environ.get("SENTRY_LOG_LEVEL")
 
     if lvl and lvl not in logging._nameToLevel: