Update logging + implement log rotation

Observed behavior

When kolibri starts, the following message is received:

INFO     Going to daemon mode, logging to /home/benjamin/.kolibri/server.log

However server.log is not the main log anymore.

Currently, we have:

• kolibri.log for general INFO level from Python
• debug.log for general DEBUG level (if switched on?)
• server.log for crash outputs when deamonized

Related issue: Icecube logging is noisy #2212

Changes to this have to be consolidated with docs.

Expected behavior

I would suggest the following naming for an easier user experience and for UIs that want to integrate a log view (highly recommended)

• log/daemon.log for sporadic crash output produced by the daemon and uncaught by other loggers
• log/kolibri.log for the latest log output
• log/kolibri-YYYY-MM-DD.log for log rotation (dates provided kindly by built-in log rotation, see KA Lite)
• log/debug.log for the latest debug output, not rotated to avoid accumulating huge logs

Icecube issue: Possibly solved by only logging Icecube progress etc. as debug output and accepting that it’s noisy.

User-facing consequences

Makes it easier to dig out logs and finalizes how we want to do logging so we don’t have to change it further down the road.

Readiness for UI implementation.

Means we can also amend the issue template regarding where to find the logs.

Updates

• ~Changed file extensions from .log to .txt – will make it easier for users on Windows to open the files~. Moved: Follow-up from https://github.com/learningequality/kolibri/issues/2512
• ~Suggestion to put rotated log files in log/archive/ to reduce user confusion~ Not easy to implement, needs modification of built-in Python logging class.

[benjaoming]

I concede that I found the patch release confusing and haven’t understood quite what the scope of 0.12.4 was, but let’s get this improvement out there to the users 🚢

[indirectlylit]

the PR was targeted for 0.12.x

0.12.y, not 0.12.x