Log format related options should not be application-specific

[Zhongyue Luo]

The options below are tightly coupled with Nova.

    cfg.StrOpt('logging_context_format_string',
               default='%(asctime)s %(levelname)s %(name)s [%(request_id)s '
                       '%(user_id)s %(project_id)s] %(instance)s'
                       '%(message)s',
               help='format string to use for log messages with context'),
    cfg.StrOpt('logging_default_format_string',
               default='%(asctime)s %(process)d %(levelname)s %(name)s [-]'
                       ' %(instance)s%(message)s',
               help='format string to use for log messages without context'),
    cfg.StrOpt('logging_exception_prefix',
               default='%(asctime)s %(process)d TRACE %(name)s %(instance)s',
               help='prefix each line of exception output with this format'),
    cfg.StrOpt('instance_format',
               default='[instance: %(uuid)s] ',
               help='If an instance is passed with the log message, format '
                    'it like this'),
    cfg.StrOpt('instance_uuid_format',
               default='[instance: %(uuid)s] ',
               help='If an instance UUID is passed with the log message, '
                    'format it like this')

The default log format in openstack-common should be minimal and each project should override these configs.

Introducing a unknown key value results with a python exception.
For example if I change the 'logging_context_format_string' to '.....%(volume)s......' in cinder, the process will complain that it couldn't find the key 'volume' in the given dict parameter.
I had to edit the process method in log.py to resolve this problem.

New entities should also be easy to define in the conf file in each project with out changing the common code.

[Mark McLoughlin (markmc)]

Yep, this makes sense - instance_format etc. certainly smells nova specific

Not sure exactly what the best answer is though

[Doug Hellmann (doug-hellmann)]

See also https://blueprints.launchpad.net/oslo.log/+spec/app-agnostic-logging-parameters