Serf Handler

handler.py

#!/usr/bin/env python
# coding: utf-8
"""
Serf class is serf event handler class.
Switch the execution method under the handlers module in the event

* tree
event-handler-root
|- handler.py
|- handlers
   |- member_join.py
   |- member_failed.py
   |- member_update.py
   |- member_leap.py
   |- user_deploy.py
   |- query_xxx.py
   |- ...
"""
from importlib import import_module
import os
import sys

class SerfHandler(object):

    def __init__(self):
        self._event = os.environ.get('SERF_EVENT', '')
        self._self_name = os.environ.get('SERF_SELF_NAME', '')
        self._user_event = os.environ.get('SERF_USER_EVENT', '')
        self._query_name = os.environ.get('SERF_QUERY_NAME', '')
        self._args = sys.stdin.readlines()

    def init_handler(self):
        if self._event == 'user':
            # user event
            self._handler_name = '{}_{}'.format(
                self._event, self._user_event)
        elif self._event == 'query':
            # query event
            self._handler_name = '{}_{}'.format(
                self._event, self._query_name)
        else:
            # memeber-join, member-failed, etc...
            self._handler_name = self._event.replace('-', '_')

      try:
          self._handler = import_module(
              'handlers.{}'.format(self._handler_name))
      except ImportError:
          self._handler = None

    def exec(self):
        if self._handler:
            main = getattr(self._handler, 'main')
            if main:
                return main(self._self_name, *self._args)
        return 0


if __name__ == '__main__':
    os.exit(Serf().exec())