baseimage-tutorial-framework/tfw/components/process_management/process_handler.py

import logging
from xmlrpc.client import Fault as SupervisorFault

from tfw.internals.networking import Scope

from .supervisor import ProcessManager, ProcessLogManager

LOG = logging.getLogger(__name__)


class ProcessHandler(ProcessManager, ProcessLogManager):
    keys = ['process']

    def __init__(self, *, supervisor_uri, log_tail=0):
        ProcessManager.__init__(self, supervisor_uri)
        ProcessLogManager.__init__(self, supervisor_uri)
        self.log_tail = log_tail

        self.commands = {
            'process.start': self.start_process,
            'process.stop': self.stop_process,
            'process.restart': self.restart_process
        }

    def handle_event(self, message, connector):
        try:
            try:
                self.commands[message['key']](message['name'])
            except SupervisorFault as fault:
                message['error'] = fault.faultString
            finally:
                message['stdout'] = self.read_stdout(
                    message['name'],
                    self.log_tail
                )
                message['stderr'] = self.read_stderr(
                    message['name'],
                    self.log_tail
                )
            connector.send_message(message, scope=Scope.WEBSOCKET)
        except KeyError:
            if not message['key'].startswith('process.log'):
                LOG.error('IGNORING MESSAGE: Invalid message received: %s', message)