Docker 容器的 RabitMQ/Pika 消费者问题

Question

I'm trying to connect my very basic consumer container to the rabbitmq container. I managed to get it working before but now it just refuses to work. Here is the consumer code

            def on_message(channel, method_frame, header_frame, body):
                print(method_frame.delivery_tag)
                print(body)
                print()
                channel.basic_ack(delivery_tag=method_frame.delivery_tag)

            print("Trying to connect 1")
            credentials = pika.PlainCredentials(username="admin", password="pass")
            print("Trying to connect 2")
            connection = pika.BlockingConnection(pika.ConnectionParameters(host='rabbitmq', credentials=credentials))
            channel = connection.channel()

            channel.queue_declare(queue='hello')
            channel.basic_qos(prefetch_count=0)

            print("abc")
            channel.basic_consume('hello', on_message)
            try:
                channel.start_consuming()
            except KeyboardInterrupt:
                channel.stop_consuming()
            connection.close()

Below is my docker-compose file:

services:

  rabbitmq:
    container_name: rabbitmq
    image: "rabbitmq:3.6-management-alpine"
    hostname: "rabbitmq-host"
    ports:
      - "5672:5672"
      - "15672:15672"
    environment:
      RABBITMQ_DEFAULT_USER: "admin"
      RABBITMQ_DEFAULT_PASS: "pass"
    networks:
      - rabbitnetwork


  clairvoyance:
    container_name: clairvoyance
    image: clairvoyance
    restart: always
    build:
      context: .
      dockerfile: docker/clairvoyance/dockerfile
    depends_on:
      - rabbitmq
    ports:
      - '8081:8081'
    networks:
      - rabbitnetwork

networks:
  rabbitnetwork:
    driver: bridge

When I run the containers, it shows in the console that rabbitmq is indeed accepting a connection:

rabbitmq        | =INFO REPORT==== 1-Jun-2022::21:04:37 ===
rabbitmq        | started TCP Listener on [::]:5672
rabbitmq        |
rabbitmq        | =INFO REPORT==== 1-Jun-2022::21:04:37 ===
rabbitmq        | accepting AMQP connection <0.401.0> (192.168.80.3:33138 -> 192.168.80.2:5672)
rabbitmq        | =INFO REPORT==== 1-Jun-2022::21:04:37 ===
rabbitmq        | connection <0.401.0> (192.168.80.3:33138 -> 192.168.80.2:5672): user 'admin' authenticated and granted access to vhost '/'

But after that, nothing happens. I never saw "abc" printed out in the console.

I tried using the RabbitMQ GUI, saw that there's an idle queue named "hello" but publishing any message to the queue does nothing.

I tried connecting a simple publisher and published a message using basic_publish, it worked. The only problem is the consumer.

Any help is greatly appreciated, thank you!

Update: Adding connection.close() right after basic_consume() will display the print("abc) message then exit(?)

Answer 1

Turns out I need ENV PYTHONUNBUFFERED=1 in my receiver's docker file for it to print out any print() statement. Weird that I don't need to do that with my publisher. To avoid this problem, one can use logging instead of print