python log formatter that shows all kwargs in extra

Question

I hope to add the following log points to my application and display the full contents of extra on console, e.g.,

logger.info('Status', extra={'foo':data})
logger.info('Status', extra={'bar':data})
logger.info('Status', extra={'foo':data, 'bar':data}) 

and I hope to see:

2016-10-10 15:28:31,408, INFO, Status, foo=data
2016-10-10 15:38:31,408, INFO, Status, bar=data
2016-10-10 15:48:31,408, INFO, Status, foo=data, bar=data

Is this even possible? According to official logging documentation, the Formatter must be set up with a format string that expects foo and bar but in my case all I want is to dump out the entire kwargs of extra without prior knowledge of foo and bar.

Answer 1

Entries of the object passed as extra will become member variables of the LogRecord.

logger.info('Status', extra={'my_params':{'foo':3, 'bar':4}})

Then you can format it as:

handler.setFormatter(logging.Formatter('%(message)s %(my_params)s'))

Which will result in the following log:

#> Status {'foo':3, 'bar':4}}

This assumes you have control over the 'extra' parameter at the time of logging.