add custom logger; add logging to /sessions and /users api (done #6)

[samjo-nyang]

• Add logging module! Special Thanks to SPARCS SSO Team
• Apply logging to session and user api

Changes:

1. added DBHandler in apps/logger.py
2. added collect-logs custom django script
3. added send-mail custom django script

Features:

1. automatically adds logs to both databases and files when logger.*** called
   • logs are saved as YYYYMMDD.pid.log format in LOG_BUFFER_DIR
2. automatically merge log files when collect-logs command is executed
   • logs are merged as YYYYMMDD.log format in LOG_DIR
   • old (> 30 days) logs are deleted from the DB
3. send mail for high-level logs
   • if DEBUG is false, high-level logs are sent to admin email
   • high-levels are warning, error and critical-level

Usages:

1. add followings to the top of the views (or backends) file

   import logging
   from apps.core.models import UserLog
   logger = logging.getLogger(UserLog.GROUP_XXX)

2. use like logger.info('login.try', {'r': request: 'uid': 'abcedf', 'extra': {'a': 1, 'b': 2}, 'hide': True})
   • r: pass the request object itself to detect the user or/and the ip
   • uid: use iff the user is not logged in (so the module cannot resolve user from request object)
     • it should be a username (of User object)
   • extra: give an extra information as dictionary
     • it will be converted into key1=value1, key2=value2, ... format
     • it will be appended after the log message
   • hide: optional flags that denotes this log is hidden to users (default is false)
3. use only info, warn, error and critical level
4. the log will be recorded as (UserLog.GROUP_XXX).login.try: a=1, b=2