JSONDecodeError when provisioning with maas storage specified

[plars]

A reported getting a JSONDecodeError in the output when trying to provision a maas system. It sounds like the user had also either specified a storage configuration, or else the system just had been configured with a default storage configuration and failed to get the block device data associated with it.

This needs investigation.
The JSONDecodeError happened because it didn't get json back from the call and it was expected. It is not maas that was supposed to generate the json, it was a method in the custom storage module for the maas device connector which runs a command to retrieve disk information about the maas node and either raises an exception if the command failed, or constructs json from the output and returns it. The command succeeded, but there was no output with which to construct the json, resulting in this corner case which was unexpected.

I would like to better understand what happened here to understand if this is a normal situation that can be recovered from, or whether it's an error condition and we should raise an exception. Reproducing this in the server lab might help if possible.

Log output from the failed provision step:

*****************************************************

* Starting testflinger provision phase on jasperoid *

*****************************************************

Traceback (most recent call last):
  File "/usr/local/bin/snappy-device-agent", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/cmd.py", line 83, in main
    sys.exit(func(args))
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/devices/__init__.py", line 321, in wrapper
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/devices/maas2/__init__.py", line 41, in provision
    device = Maas2(args.config, args.job_data)
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/devices/maas2/maas2.py", line 51, in __init__
    self.maas_storage = MaasStorage(self.maas_user, self.node_id)
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/devices/maas2/maas_storage.py", line 40, in __init__
    self.node_info = self._node_read()
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/devices/maas2/maas_storage.py", line 56, in _node_read
    return self.call_cmd(cmd, output_json=True)
  File "/usr/local/lib/python3.8/dist-packages/testflinger_device_connectors/devices/maas2/maas_storage.py", line 84, in call_cmd
    return json.loads(output)
  File "/usr/lib/python3.8/json/__init__.py", line 357, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.8/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.8/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

[syncronize-issues-to-jira]

Thank you for reporting us your feedback!

The internal ticket has been created: https://warthogs.atlassian.net/browse/CERTTF-323.

This message was autogenerated