class CustomConsumer(ConsumerStep):
    queue = Queue('custom', Exchange('custom'), routing_key='custom')

def __init__(self, c, enable_custom_consumer=False, **kwargs):
    self.enable = self.enable_custom_consumer

def get_consumers(self, connection):
    return [Consumer(connection.channel(), queues=[self.queue], callbacks=[
        self.on_message])]

def on_message(self, body, message):
    print('GOT MESSAGE: %r' % (body,))
message.ack()
celery = Celery(broker='amqp://localhost//')
celery.steps['consumer'].add(CustomConsumer)
Using Celery with existing RabbitMQ messages