Logging server demo

import logging

from os import path
from sys import stdout

from multiprocessing import Process

from zmq import Context
from zmq.backend.cython.constants import SUB, SUBSCRIBE, PUSH, PULL

PATH_ABS = path.dirname(path.realpath(__file__))
PATH_LOGS = path.join(PATH_ABS, 'logs')

NBR_WORKERS = 5

FRONTEND_PORT = '17770'
FRONTEND_SERVER = '127.0.0.1'

BACKEND_PORT = '17771'
BACKEND_SERVER = '127.0.0.2'


class Logger:
    def __init__(self):
        super().__init__()
        self.ctx = \
            self.backend = \
            self.frontend = None
        self.processes = []

        formatter = logging.Formatter(
            '%(levelname)s:%(asctime)s:%(message)s',
            datefmt='%Y/%m/%d %I-%M-%S %p'
        )

        lg = self.logger = logging.getLogger()
        lg.setLevel(logging.DEBUG)

        fh = logging.FileHandler(path.join(PATH_LOGS, 'logfile.log'))
        fh.setFormatter(formatter)
        lg.addHandler(fh)

        sdt = logging.StreamHandler(stdout)
        sdt.setFormatter(formatter)
        lg.addHandler(sdt)

        lg.info('Logging service started')

    def start(self, nbr_workers):
        ctx = Context()

        self.frontend = ctx.socket(SUB)
        self.frontend.setsockopt_string(SUBSCRIBE, '')
        self.frontend.bind(f'tcp://{FRONTEND_SERVER}:{FRONTEND_PORT}')

        # Workers connect to the backend
        self.backend = ctx.socket(PUSH)
        self.backend.bind(f'tcp://{BACKEND_SERVER}:{BACKEND_PORT}')

        for idx in range(nbr_workers):
            self.spawn(self.worker, idx)

        while True:
            request = self.frontend.recv_multipart()
            self.backend.send_multipart(request)

    # Start daemon worker tasks
    def spawn(self, task, *args):
        process = Process(target=task, args=args)
        self.processes.append(process)
        process.daemon = True
        process.start()

    def worker(self, index):
        socket = Context().socket(PULL)
        socket.connect(f'tcp://{BACKEND_SERVER}:{BACKEND_PORT}')

        identity = f'LogSlave-{index}'
        socket.identity = identity.encode('utf-8')
        self.logger.log(logging.INFO, f'{identity} started')

        while True:
            errorlevel, message = socket.recv_multipart()
            message = message.decode('utf-8').rstrip('\n')
            errorlevel = errorlevel.decode('utf-8')
            self.logger.log(getattr(logging, errorlevel), message)


logger = Logger()
logger.start(NBR_WORKERS)