[gestion/trigger] Début du remplaçant de generate.

* Trigger permet de régénérer tous les services d'un hôte, ou
 des services spécifiques.
 * trigger.py -h permet de voir les services disponibles.
 * Trigger surcharge cmb pour créer un écouteur d'événements qui
 peut régénérer des services à la volée.
 * Trigger mériterait d'être un peu documenté.

gestion/trigger/trigger.py

@@ -0,0 +1,112 @@
+#!/bin/bash /usr/scripts/python.sh
+# -*- coding: utf-8 -*-
+#
+# Trigger library, designed to be called on any host, it will
+# retreive its appropriate modules based on the hostname. Based
+# on the Crans Message Broker stuff, it adds specific methods designed
+# to be used as a replacement for generate
+#
+# Author    : Pierre-Elliott Bécue <becue@crans.org>
+# License   : GPLv3
+# Date      : 29/04/2014
+
+import argparse
+import cranslib.clogger as clogger
+import cmb
+import cPickle
+import socket
+import gestion.config.trigger as trigger_config
+import gestion.affichage as affichage
+import sys
+
+hostname = socket.gethostname().split(".")[0]
+
+import importlib
+triggerhost = importlib.import_module("gestion.trigger.hosts.%s" % (hostname,))
+logger = clogger.CLogger("trigger", "info")
+
+class EvenementListener(cmb.AsynchronousConsumer):
+    """
+    Gestionnaire d'événement
+    """
+
+    def on_message(self, channel, basic_deliver, properties, body):
+        """Invoked by pika when a message is delivered from RabbitMQ. The
+        channel is passed for your convenience. The basic_deliver object that
+        is passed in carries the exchange, routing key, delivery tag and
+        a redelivered flag for the message. The properties passed in is an
+        instance of BasicProperties with the message properties and the body
+        is the message that was sent.
+
+        :param pika.channel.Channel channel: The channel object
+        :param pika.Spec.Basic.Deliver: basic_deliver method
+        :param pika.Spec.BasicProperties: properties
+        :param str|unicode body: The message body
+
+        """
+        about = basic_deliver.routing_key.split(".")[1]
+        origin = properties.app_id
+        message_id = properties.message_id
+        logger.info('Received message # %s from %s: %s',
+                    basic_deliver.delivery_tag, properties.app_id, body)
+        body = cPickle.loads(body)
+        try:
+            triggerhost.trigger(about)(body)
+        except AttributeError:
+            logger.warning('No suitable trigger found for message # %s from %s: %s on host %s. Discarding it.',
+                           basic_deliver.delivery_tag, properties.app_id, body, hostname)
+        self.acknowledge_message(basic_deliver.delivery_tag)
+
+    def run(self):
+        """Run the example consumer by connecting to RabbitMQ and then
+        starting the IOLoop to block and allow the SelectConnection to operate.
+
+        """
+        logger.info("""Crans Message Broker
++--------------------------------------------+
+|              Welcome on CMB                |
++--------------------------------------------+""")
+        self._connection = self.connect()
+        for service in trigger_config.services[hostname]:
+            self.add_queue("trigger-%s-%s" % (hostname, service), "trigger.%s" % (service,))
+        self._connection.ioloop.start()
+
+def daemonize():
+    listener = EvenementListener(trigger_config.master, "trigger", "topic")
+    try:
+        listener.run()
+    except KeyboardInterrupt:
+        logger.warning("Caught SIGINT, will now go for shutdown.")
+        listener.stop()
+
+if __name__ == '__main__':
+    # We use a parser to capture all possible arguments designed for one host
+    parser = argparse.ArgumentParser(description="Initier une régénération de services.", add_help=False)
+    parser.add_argument('-a', '--all', help="Régénération complète des services sur l'hôte %s." % (hostname,), action="store_true")
+    parser.add_argument('-d', '--daemon', help="Écouter sur civet en arrière plan.", action="store_true")
+    parser.add_argument('-h', '--help', help="Affiche ce message et quitte.", action="store_true")
+    # For each service supposingly managed by host, generate one parser option
+    for service in trigger_config.services[hostname]:
+        parser.add_argument('--%s' % (service,), help="Force la régénération du service %s." % (service,), action="store_true")
+    args = parser.parse_args()
+
+    if args.help:
+        parser.print_help()
+        sys.exit(0)
+    elif args.all:
+        # Regenerates all services availables, don't crash on nonexistant ones
+        for service in trigger_config.services[hostname]:
+            try:
+                print affichage.style("        (Ré)Génération du service %s" % (service,), "cyan")
+                triggerhost.trigger(service)(True)
+            except AttributeError:
+                print "No suitable trigger handle found for service %s on host %s" % (service, hostname)
+    elif args.daemon:
+        # Daemonize the trigger app, in order to listen and execute commands from civet.
+        daemonize()
+    else:
+        # If not all and not daemon, try all services one by one.
+        for service in trigger_config.services[hostname]:
+            if getattr(args, service, False) == True:
+                print affichage.style("        (Ré)Génération du service %s" % (service,), "cyan")
+                triggerhost.trigger(service)(True)