Address wrong socket type error

[andy-maier]

Every now and then, presumably when Prometheus contacts the exporter using https or when a browser directed to the export port uses https, the exporter thread that serves the export port, shows an OSError complaining about the wrong socket type. The exporter is still functional after showing the error.

[andy-maier]

Example when calling with -vv:

Collecting metrics
Fetching metrics from HMC
Building family objects
Returning family objects
Done collecting metrics
Traceback (most recent call last):
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/wsgiref/handlers.py", line 138, in run
    self.finish_response()
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/wsgiref/handlers.py", line 184, in finish_response
    self.write(data)
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/wsgiref/handlers.py", line 288, in write
    self.send_headers()
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/wsgiref/handlers.py", line 346, in send_headers
    self.send_preamble()
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/wsgiref/handlers.py", line 272, in send_preamble
    self._write(('Server: %s\r\n' % self.server_software).encode('iso-8859-1'))
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/wsgiref/handlers.py", line 467, in _write
    result = self.stdout.write(data)
  File "/usr/local/opt/[email protected]/Frameworks/Python.framework/Versions/3.8/lib/python3.8/socketserver.py", line 799, in write
    self._sock.sendall(b)
OSError: [Errno 41] Protocol wrong type for socket
Collecting metrics
Fetching metrics from HMC
Building family objects
Returning family objects
Done collecting metrics

Environment:

• zhmc_prometheis_exporter from master as of 2021-03-17
• prometheus-client 0.9.0
• Python 3.8.7 on macOS