Add logging to stderr

f2b-responder.py

@@ -9,6 +9,7 @@ from signal import SIGTERM, signal
 from socket import AF_INET6, IPPROTO_IPV6, IPV6_V6ONLY, socket
 from sqlite3 import connect
 from string import ascii_lowercase
+from sys import stderr
 from tempfile import gettempdir
 from threading import Thread
 from types import FrameType
@@ -23,6 +24,11 @@ graph_printf %3.0lf
 """
 
 
+def _log_message(message: str) -> None:
+    'Do a simple log on `stderr`.'
+    stderr.write(f'=== {message}\n')
+
+
 class _JailInfo(NamedTuple):
     id: int
     name: str
@@ -130,7 +136,7 @@ server = DualStackThreadingHttpServer(
 
 def shutdown(signalnum: int, frame: FrameType | None):
     'Shut down upon SIGTERM.'
-    print('Shutting down.')
+    _log_message('Shutting down.')
     server.shutdown()
 
 
@@ -138,10 +144,10 @@ if __name__ == '__main__':
     signal(signalnum=SIGTERM, handler=shutdown)
     run_thread = Thread(
         target=server.serve_forever, kwargs=dict(poll_interval=1))
-    print('Serving.')
+    _log_message('Serving.')
     run_thread.start()
     try:
         run_thread.join()
     except KeyboardInterrupt:
         pass
-    print('Server is shut down.')
+    _log_message('Server is shut down.')