Terminating the exporter causes Python traceback to be shown when running in Docker

[andy-maier]

When running the exporter in a Docker container on macos, stopping it with Ctrl-C creates a traceback, as shown:

Exporter is up and running on port 9291
^CExporter interrupted after server start.
Cleaning up metrics context on HMC
Cleaning up notification subscription on HMC
  File "/usr/local/bin/zhmc_prometheus_exporter", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.9/site-packages/zhmc_prometheus_exporter/zhmc_prometheus_exporter.py", line 1731, in main
    cleanup(session, context, resources)
  File "/usr/local/lib/python3.9/site-packages/zhmc_prometheus_exporter/zhmc_prometheus_exporter.py", line 715, in cleanup
    res.disable_auto_update()
  File "/usr/local/lib/python3.9/site-packages/zhmcclient/_resource.py", line 556, in disable_auto_update
    session.unsubscribe_auto_update()
  File "/usr/local/lib/python3.9/site-packages/decorator.py", line 232, in fun
    return caller(func, *(extras + args), **kw)
  File "/usr/local/lib/python3.9/site-packages/zhmcclient/_logging.py", line 227, in log_api_call
    result = func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/zhmcclient/_session.py", line 1343, in unsubscribe_auto_update
    self._resource_updater.close()
  File "/usr/local/lib/python3.9/site-packages/decorator.py", line 232, in fun
    return caller(func, *(extras + args), **kw)
  File "/usr/local/lib/python3.9/site-packages/zhmcclient/_logging.py", line 227, in log_api_call
    result = func(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/zhmcclient/_resource_updater.py", line 108, in close
    self._conn.disconnect()
  File "/usr/local/lib/python3.9/site-packages/stomp/connect.py", line 172, in disconnect
    Protocol11.disconnect(self, receipt, headers, **keyword_headers)
  File "/usr/local/lib/python3.9/site-packages/stomp/protocol.py", line 351, in disconnect
    traceback.print_stack()
Closing session with HMC

Environment for the above case:

• zhmc-prometheus-exporter: 1.4.0
• stomp.py: 6.0.0
• Python environment: Python 3.9.16 in debian in Docker container on macos

This does not happen when the exporter is run on macos directly (in a virtualenv).

Exporter is up and running on port 9291
^CExporter interrupted after server start.
Cleaning up metrics context on HMC
Cleaning up notification subscription on HMC
Closing session with HMC

Environment for the above case:

• zhmc-prometheus-exporter: 1.4.0
• stomp.py: 6.0.0
• Python environment: Python 3.9.16 in virtualenv on macos