Understanding how to connect to the public Fedora broker from outside using library

[changlinli]

Using fedora-messaging --conf=conf.toml consume --callback=fedora_messaging.example:printer I can successfully connect and see messages printing out.

Unfortunately when I run what I think is the equivalent code from the docs, I get nothing printed out to stdout at all (not even any connection information).

from fedora_messaging import api

# First, define a function to be used as our callback. This will be called
# whenever a message is received from the server.
def printer_callback(message):
    """
    Print the message to standard output.

    Args:
        message (fedora_messaging.message.Message): The message we received
            from the queue.
    """
    print(str(message))

# Next, we need a queue to consume messages from. We can define
# the queue and binding configurations in these dictionaries:
queues = {
    '00000000-0000-0000-0000-000000000000': {
        'durable': False,  # Delete the queue on broker restart
        'auto_delete': True,  # Delete the queue when the client terminates
        'exclusive': False,  # Allow multiple simultaneous consumers
        'arguments': {},
    },
}
binding = {
    'exchange': 'amq.topic',  # The AMQP exchange to bind our queue to
    'queue': '00000000-0000-0000-0000-000000000000',  # The unique name of our queue on the AMQP broker
    'routing_keys': ['#'],  # The topics that should be delivered to the queue
}

# Start consuming messages using our callback. This call will block until
# a KeyboardInterrupt is raised, or the process receives a SIGINT or SIGTERM
# signal.
api.consume(printer_callback, bindings=binding, queues=queues)

This is even if I set the FEDORA_MESSAGING_CONF environment variable to conf.toml. Is there some other configuration or logging that I'm missing?

[praiskup]

See #171 and #186. The example from docs doesn't work. Well I spent quite some time on trying to make this work (without success) ... and seems like I'm not alone.

I'd suggest at least to turn on the debugging output by default in the example, and while on it - consider adding a warning that it currently doesn't work.

[jeremycline]

It would be good to add the log configuration setup to the snippet, yes.

[changlinli]

@jeremycline After #192 I now get a clearer idea of what's wrong (this also saves me the effort of opening another ticket for trying to connect via Java's RabbitMQ library) so thanks a bunch!

I'm now seeing

[INFO fedora_messaging._session] Authenticating with server using x509 (certfile: fedora-cert.pem, keyfile: fedora-key.pem)
[INFO fedora_messaging._session] Connecting to rabbitmq.fedoraproject.org:5671
[INFO fedora_messaging._session] Successfully opened connection to rabbitmq.fedoraproject.org
[WARNING pika.channel] Received remote Channel.Close (403): "ACCESS_REFUSED - access to exchange 'amq.topic' in vhost '/public_pubsub' refused for user 'fedora'" on <Channel number=1 OPEN conn=<SelectConnection OPEN transport=<pika.adapters.utils.io_services_utils._AsyncSSLTransport object at 0x7f2872d1c588> params=<URLParameters host=rabbitmq.fedoraproject.org port=5671 virtual_host=/public_pubsub ssl=True>>>
[INFO fedora_messaging._session] Channel <Channel number=1 CLOSED conn=<SelectConnection OPEN transport=<pika.adapters.utils.io_services_utils._AsyncSSLTransport object at 0x7f2872d1c588> params=<URLParameters host=rabbitmq.fedoraproject.org port=5671 virtual_host=/public_pubsub ssl=True>>> closed (403): ACCESS_REFUSED - access to exchange 'amq.topic' in vhost '/public_pubsub' refused for user 'fedora'

and nothing else prints after that.

[jeremycline]

@changlinli can you attach your configuration file. the code snippet you're running, and the commit you've got checked out? I did a test against the Fedora /public_pubsub vhost after the fix and it worked fine so I'll need to see your specific setup to reproduce it.

Thanks!

[changlinli]

@jeremycline It looks like updating to the latest version of fedora-messaging did the trick! Thank you very much!

[changlinli]

There's still a minor issue with the current docs that I've put in a small PR for here: #193