Request: Change background-color of logger messages by Logging Level

[alexlenail]

I love jupyter notebook. Frequently I use packages I write from jupyter. Some of those packages have loggers which logger.info('information'). In jupyter, those messages show up below the code window in an angry magenta. That seems appropriate for logger.error or logger.critical but logger.info could have a more pleasant, calming color, so that my code doesn't look terribly broken when just trying to keep you in the loop about what it's up to. :)

Logging levels reference.

[takluyver]

I think the default log handler writes messages to the stderr stream. We display stderr output with a red background to distinguish it from stdout - though this is a questionable decision, since output on stderr does not necessarily mean there's a problem.

There are a couple of ways you could distinguish different log levels:

• Use a logging formatter to embed ANSI colour codes into the text (Tornado has such a formatter, for example), and configure the StreamHandler to write to stdout instead of stderr (avoiding the red background).
• Write a custom logging handler which sends Jupyter display_data messages to display logging information as HTML, which gives much more control of how it appears. This would be a bit more work, but it would be an interesting contribution to the ecosystem; it could be released as a standalone package for people to use.

[alexlenail]

Sounds good. Thanks @takluyver !

[lzkelley]

@takluyver the mentality behind a red stderr message seems reasonable, but then why isn't the background errors themselves red?