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import json |
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import pickle |
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import eventlet |
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import pika |
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from pika.credentials import PlainCredentials |
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from st2reactor.sensor.base import Sensor |
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DESERIALIZATION_FUNCTIONS = { |
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'json': json.loads, |
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'pickle': pickle.loads |
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} |
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class RabbitMQQueueSensor(Sensor): |
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"""Sensor which monitors a RabbitMQ queue for new messages |
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This is a RabbitMQ Queue sensor i.e. it works on the simplest RabbitMQ |
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messaging model as described in https://www.rabbitmq.com/tutorials/tutorial-one-python.html. |
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It is capable of simultaneously consuming from multiple queues. Each message is |
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dispatched to stackstorm as a `rabbitmq.new_message` TriggerInstance. |
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""" |
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def __init__(self, sensor_service, config=None): |
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super(RabbitMQQueueSensor, self).__init__(sensor_service=sensor_service, config=config) |
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self._logger = self._sensor_service.get_logger(name=self.__class__.__name__) |
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self.host = self._config['sensor_config']['host'] |
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self.username = self._config['sensor_config']['username'] |
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self.password = self._config['sensor_config']['password'] |
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queue_sensor_config = self._config['sensor_config']['rabbitmq_queue_sensor'] |
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self.queues = queue_sensor_config['queues'] |
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if not isinstance(self.queues, list): |
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self.queues = [self.queues] |
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self.deserialization_method = queue_sensor_config['deserialization_method'] |
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supported_methods = DESERIALIZATION_FUNCTIONS.keys() |
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if self.deserialization_method and self.deserialization_method not in supported_methods: |
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raise ValueError('Invalid deserialization method specified: %s' % |
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(self.deserialization_method)) |
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self.conn = None |
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self.channel = None |
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def run(self): |
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self._logger.info('Starting to consume messages from RabbitMQ for %s', self.queues) |
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# run in an eventlet in-order to yield correctly |
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gt = eventlet.spawn(self.channel.start_consuming) |
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# wait else the sensor will quit |
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gt.wait() |
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def cleanup(self): |
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if self.conn: |
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self.conn.close() |
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def setup(self): |
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if self.username and self.password: |
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credentials = PlainCredentials(username=self.username, password=self.password) |
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connection_params = pika.ConnectionParameters(host=self.host, credentials=credentials) |
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else: |
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connection_params = pika.ConnectionParameters(host=self.host) |
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self.conn = pika.BlockingConnection(connection_params) |
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self.channel = self.conn.channel() |
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self.channel.basic_qos(prefetch_count=1) |
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# Setup Qs for listening |
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for queue in self.queues: |
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self.channel.queue_declare(queue=queue, durable=True) |
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def callback(ch, method, properties, body): |
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self._dispatch_trigger(ch, method, properties, body, queue) |
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self.channel.basic_consume(callback, queue=queue) |
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def _dispatch_trigger(self, ch, method, properties, body, queue): |
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body = self._deserialize_body(body=body) |
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self._logger.debug('Received message for queue %s with body %s', queue, body) |
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payload = {"queue": queue, "body": body} |
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try: |
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self._sensor_service.dispatch(trigger="rabbitmq.new_message", payload=payload) |
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finally: |
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self.channel.basic_ack(delivery_tag=method.delivery_tag) |
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def update_trigger(self, trigger): |
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pass |
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def add_trigger(self, trigger): |
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pass |
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def remove_trigger(self, trigger): |
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pass |
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def _deserialize_body(self, body): |
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if not self.deserialization_method: |
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return body |
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deserialization_func = DESERIALIZATION_FUNCTIONS[self.deserialization_method] |
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try: |
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body = deserialization_func(body) |
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except Exception: |
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pass |
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return body |
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StackStorm /
st2contrib
