root / snf-cyclades-app / synnefo / logic / dispatcher.py @ df36a125
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#!/usr/bin/env python
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# Copyright 2011 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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#
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in the
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# documentation and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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# SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and documentation are
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# those of the authors and should not be interpreted as representing official
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# policies, either expressed or implied, of GRNET S.A.
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""" Message queue setup, dispatch and admin
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This program sets up connections to the queues configured in settings.py
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and implements the message wait and dispatch loops. Actual messages are
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handled in the dispatched functions.
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"""
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from django.core.management import setup_environ |
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# Fix path to import synnefo settings
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import sys |
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import os |
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path = os.path.normpath(os.path.join(os.getcwd(), '..'))
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sys.path.append(path) |
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from synnefo import settings |
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setup_environ(settings) |
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from django.db import close_connection |
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import time |
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import daemon |
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import daemon.runner |
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from lockfile import LockTimeout |
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# Take care of differences between python-daemon versions.
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try:
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from daemon import pidfile as pidlockfile |
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except:
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from daemon import pidlockfile |
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import setproctitle |
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from synnefo.lib.amqp import AMQPClient |
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from synnefo.logic import callbacks |
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from synnefo.logic import queues |
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import logging |
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log = logging.getLogger("dispatcher")
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log_amqp = logging.getLogger("amqp")
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log_logic = logging.getLogger("synnefo.logic")
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LOGGERS = [log, log_amqp, log_logic] |
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class Dispatcher: |
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debug = False
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def __init__(self, debug=False): |
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self.debug = debug
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self._init()
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def wait(self): |
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log.info("Waiting for messages..")
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timeout = 600
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while True: |
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try:
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# Close the Django DB connection before processing
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# every incoming message. This plays nicely with
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# DB connection pooling, if enabled and allows
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# the dispatcher to recover from broken connections
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# gracefully.
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close_connection() |
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msg = self.client.basic_wait(timeout=timeout)
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if not msg: |
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log.warning("Idle connection for %d seconds. Will connect"
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" to a different host. Verify that"
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" snf-ganeti-eventd is running!!", timeout)
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self.client.reconnect()
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except SystemExit: |
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break
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except Exception as e: |
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log.exception("Caught unexpected exception: %s", e)
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self.client.basic_cancel()
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self.client.close()
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def _init(self): |
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log.info("Initializing")
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self.client = AMQPClient(logger=log_amqp)
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# Connect to AMQP host
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self.client.connect()
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# Declare queues and exchanges
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exchange = settings.EXCHANGE_GANETI |
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exchange_dl = queues.convert_exchange_to_dead(exchange) |
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self.client.exchange_declare(exchange=exchange,
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type="topic")
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self.client.exchange_declare(exchange=exchange_dl,
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type="topic")
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for queue in queues.QUEUES: |
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# Queues are mirrored to all RabbitMQ brokers
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self.client.queue_declare(queue=queue, mirrored=True, |
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dead_letter_exchange=exchange_dl) |
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# Declare the corresponding dead-letter queue
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queue_dl = queues.convert_queue_to_dead(queue) |
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self.client.queue_declare(queue=queue_dl, mirrored=True) |
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# Bind queues to handler methods
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for binding in queues.BINDINGS: |
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try:
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callback = getattr(callbacks, binding[3]) |
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except AttributeError: |
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log.error("Cannot find callback %s", binding[3]) |
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raise SystemExit(1) |
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queue = binding[0]
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exchange = binding[1]
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routing_key = binding[2]
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self.client.queue_bind(queue=queue, exchange=exchange,
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routing_key=routing_key) |
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self.client.basic_consume(queue=binding[0], |
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callback=callback, |
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prefetch_count=5)
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queue_dl = queues.convert_queue_to_dead(queue) |
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exchange_dl = queues.convert_exchange_to_dead(exchange) |
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# Bind the corresponding dead-letter queue
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self.client.queue_bind(queue=queue_dl,
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exchange=exchange_dl, |
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routing_key=routing_key) |
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log.debug("Binding %s(%s) to queue %s with handler %s",
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exchange, routing_key, queue, binding[3])
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def parse_arguments(args): |
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from optparse import OptionParser |
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default_pid_file = \ |
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os.path.join(".", "var", "run", "synnefo", "dispatcher.pid")[1:] |
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parser = OptionParser() |
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parser.add_option("-d", "--debug", action="store_true", default=False, |
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dest="debug", help="Enable debug mode") |
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parser.add_option("-w", "--workers", default=2, dest="workers", |
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help="Number of workers to spawn", type="int") |
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parser.add_option("-p", "--pid-file", dest="pid_file", |
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default=default_pid_file, |
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help="Save PID to file (default: %s)" % default_pid_file)
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parser.add_option("--purge-queues", action="store_true", |
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default=False, dest="purge_queues", |
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help="Remove all declared queues (DANGEROUS!)")
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parser.add_option("--purge-exchanges", action="store_true", |
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default=False, dest="purge_exchanges", |
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help="Remove all exchanges. Implies deleting all queues \
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first (DANGEROUS!)")
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parser.add_option("--drain-queue", dest="drain_queue", |
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help="Strips a queue from all outstanding messages")
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return parser.parse_args(args)
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def purge_queues(): |
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"""
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Delete declared queues from RabbitMQ. Use with care!
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"""
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client = AMQPClient(max_retries=120)
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client.connect() |
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print "Queues to be deleted: ", queues.QUEUES |
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if not get_user_confirmation(): |
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return
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for queue in queues.QUEUES: |
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result = client.queue_delete(queue=queue) |
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print "Deleting queue %s. Result: %s" % (queue, result) |
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client.close() |
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def purge_exchanges(): |
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"""Delete declared exchanges from RabbitMQ, after removing all queues"""
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purge_queues() |
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client = AMQPClient() |
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client.connect() |
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exchanges = queues.EXCHANGES |
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print "Exchanges to be deleted: ", exchanges |
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if not get_user_confirmation(): |
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return
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for exch in exchanges: |
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result = client.exchange_delete(exchange=exch) |
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print "Deleting exchange %s. Result: %s" % (exch, result) |
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client.close() |
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def drain_queue(queue): |
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"""Strip a (declared) queue from all outstanding messages"""
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if not queue: |
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return
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if not queue in queues.QUEUES: |
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print "Queue %s not configured" % queue |
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return
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print "Queue to be drained: %s" % queue |
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if not get_user_confirmation(): |
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return
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client = AMQPClient() |
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client.connect() |
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tag = client.basic_consume(queue=queue, callback=callbacks.dummy_proc) |
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print "Queue draining about to start, hit Ctrl+c when done" |
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time.sleep(2)
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print "Queue draining starting" |
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num_processed = 0
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while True: |
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client.basic_wait() |
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num_processed += 1
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sys.stderr.write("Ignored %d messages\r" % num_processed)
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client.basic_cancel(tag) |
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client.close() |
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def get_user_confirmation(): |
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ans = raw_input("Are you sure (N/y):") |
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if not ans: |
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return False |
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if ans not in ['Y', 'y']: |
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return False |
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return True |
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def debug_mode(): |
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disp = Dispatcher(debug=True)
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disp.wait() |
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def daemon_mode(opts): |
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disp = Dispatcher(debug=False)
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disp.wait() |
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def setup_logging(opts): |
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import logging |
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formatter = logging.Formatter("%(asctime)s %(name)s %(module)s"
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" [%(levelname)s] %(message)s")
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if opts.debug:
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log_handler = logging.StreamHandler() |
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log_handler.setFormatter(formatter) |
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else:
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import logging.handlers |
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log_file = "/var/log/synnefo/dispatcher.log"
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log_handler = logging.handlers.WatchedFileHandler(log_file) |
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log_handler.setFormatter(formatter) |
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for l in LOGGERS: |
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l.addHandler(log_handler) |
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l.setLevel(logging.DEBUG) |
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def main(): |
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(opts, args) = parse_arguments(sys.argv[1:])
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# Rename this process so 'ps' output looks like this is a native
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# executable. Can not seperate command-line arguments from actual name of
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# the executable by NUL bytes, so only show the name of the executable
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# instead. setproctitle.setproctitle("\x00".join(sys.argv))
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setproctitle.setproctitle(sys.argv[0])
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setup_logging(opts) |
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# Special case for the clean up queues action
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if opts.purge_queues:
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purge_queues() |
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return
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# Special case for the clean up exch action
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if opts.purge_exchanges:
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purge_exchanges() |
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return
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if opts.drain_queue:
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drain_queue(opts.drain_queue) |
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return
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# Debug mode, process messages without daemonizing
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if opts.debug:
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debug_mode() |
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return
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# Create pidfile,
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pidf = pidlockfile.TimeoutPIDLockFile(opts.pid_file, 10)
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if daemon.runner.is_pidfile_stale(pidf):
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log.warning("Removing stale PID lock file %s", pidf.path)
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pidf.break_lock() |
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files_preserve = [] |
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for handler in log.handlers: |
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stream = getattr(handler, 'stream') |
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if stream and hasattr(stream, 'fileno'): |
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files_preserve.append(handler.stream) |
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stderr_stream = None
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for handler in log.handlers: |
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stream = getattr(handler, 'stream') |
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if stream and hasattr(handler, 'baseFilename'): |
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stderr_stream = stream |
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break
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daemon_context = daemon.DaemonContext( |
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pidfile=pidf, |
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umask=0022,
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stdout=stderr_stream, |
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stderr=stderr_stream, |
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files_preserve=files_preserve) |
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try:
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daemon_context.open() |
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except (pidlockfile.AlreadyLocked, LockTimeout):
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log.critical("Failed to lock pidfile %s, another instance running?",
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pidf.path) |
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sys.exit(1)
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log.info("Became a daemon")
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if 'gevent' in sys.modules: |
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# A fork() has occured while daemonizing. If running in
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# gevent context we *must* reinit gevent
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log.debug("gevent imported. Reinitializing gevent")
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import gevent |
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gevent.reinit() |
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# Catch every exception, make sure it gets logged properly
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try:
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daemon_mode(opts) |
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except Exception: |
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log.exception("Unknown error")
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raise
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if __name__ == "__main__": |
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sys.exit(main()) |
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# vim: set sta sts=4 shiftwidth=4 sw=4 et ai :
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