snmp-3com-agent-daemon

#!/usr/bin/python3 -tt

# Twisted hosts our website and helps with async tasks.
# The application threads are structured in the following way:
#
#  reactor
#   `-- agent (1 thread)
#   `-- workers (2 threads)
#
from twisted.internet import reactor
# from twisted.web.wsgi import WSGIResource
# from twisted.web.server import Site
# from twisted.python.threadpool import ThreadPool
from twisted.python import log

# Data are accessed through SQLSoup, using SQLAlchemy.
from sqlalchemy.orm import scoped_session, sessionmaker
from sqlalchemy import create_engine

# Command line arguments follow the GNU conventions.
from getopt import gnu_getopt
from sys import argv, stderr

# Configuration is stored in a simple ini file.
from configparser import ConfigParser

# Import all the application handles.
from adminator import SNMP3comAgent
from sqlmodel import Session

if __name__ == '__main__':
    def do_start(config):
        # Start Twisted logging to console.
        log.startLogging(stderr)

        # Read database configuration options.
        db_url = config.get('database', 'url')

        # Default to much saner database query defaults and always
        # commit and/or flush statements explicitly.
        # unused
        # factory = sessionmaker(autocommit=False, autoflush=False)

        # Prepare database connection with table reflection.
        engine = create_engine(db_url, echo=True)

        # factory to create scoped_session of type Session (from sqlmodel, not sqlalchemy)
        # to avoid multi-threading problems in new versions of things
        def sqlmodel_factory():
            return Session(engine, autoflush=False)

        db = scoped_session(sqlmodel_factory)
        #db.schema = 'topology'

        # Extract agent options, sans the pool_size we handle here.
        agent_opts = dict(config.items('snmp-3com'))
        # agent_opts = dict()
        agent_pool = int(agent_opts.pop('pool_size', 2))

        # Set the correct thread pool size for the agent.
        reactor.suggestThreadPoolSize(agent_pool)

        # Prepare the agent that runs in an exclusive thread.
        agent = SNMP3comAgent(db, **agent_opts)

        # Run the startup code as the first thing.
        reactor.callLater(0, agent.start)

        # Run the Twisted reactor until the user terminates us.
        reactor.run()

    def do_help(*args, **kwargs):
        print('Usage: ifstatus-agent-daemon [--config=/etc/adminator.ini]')
        print('')
        print('The agent synchronizes interface status to database.')
        print('')
        print('OPTIONS:')
        print('  --help, -h          Display this help.')
        print('  --version, -V       Display version info.')
        print('')
        print('  --config, -c file   Load alternative configuration file.')
        print('')
        print('Report bugs at <http://github.com/techlib/adminator>.')

    def do_version(*args, **kwargs):
        print('snmp3com-agent-daemon (NTK) 0.1')

    # Parse command line arguments.
    opts, args = gnu_getopt(argv, 'hVc:', ['help', 'version', 'config='])

    action = do_start
    config_path = '/etc/adminator.ini'

    for k, v in opts:
        if k in ('--help', '-h'):
            action = do_help
        elif k in ('--version', '-V'):
            action = do_version
        elif k in ('--config', '-c'):
            config_path = v

    # Load the configuration from file.
    if action not in (do_help, do_version):
        config = ConfigParser()
        config.read(config_path)

    # Load the configuration from file.
    config = ConfigParser()
    config.read(config_path)

    # Perform the selected action.
    action(config=config)

# vim:set sw=4 ts=4 et:
# -*- coding: utf-8 -*-