Every attempt to subscribe results in a timeout

[ConorHartin]

I'm new to this library and wanted to test out the basics, cribbing from the sample code. Here are lines I've entered into my interpreter.

from awsiot import mqtt5_client_builder

    certkey_prefix = "mqttClient"
    client = mqtt5_client_builder.mtls_from_path(
        cert_filepath=f"{certkey_prefix}.cert.pem",
        pri_key_filepath=f"{certkey_prefix}.private.key",
        ca_filepath=ca_filepath,
        endpoint=endpoint,
        on_publish_received=lambda x: print(x),
    )
    topic = "feedback"
    from awscrt.mqtt5 import Subscription, SubscribePacket, QoS

    subscribe_future = client.subscribe(
        subscribe_packet=SubscribePacket(
            subscriptions=[Subscription(topic_filter=topic, qos=QoS.AT_LEAST_ONCE)]
        )
    )
    TIMEOUT = 100
    suback = subscribe_future.result(TIMEOUT)

That last line getting the result of the future always results in:

Traceback (most recent call last):
File "C:\Program Files\JetBrains\PyCharm 2023.1\plugins\python\helpers\pydev\pydevconsole.py", line 364, in runcode
coro = func()
File "", line 1, in
File "blahblahblah\Python\Python310\lib\concurrent\futures_base.py", line 460, in result
raise TimeoutError()
concurrent.futures._base.TimeoutError

It's plausible I've screwed up somewhere configuring the builder, but the error doesn't give me any indication as to what's wrong. I haven't shared the endpoint, because it's not intended to be public, but it ends in "iot.us-{region}.amazonaws.com" and is already working for a different IoT application written in Javascript.

[MikeDombo]

Hi there, looks like you didn't call start on the client. The client is not actually connected: https://github.com/aws/aws-iot-device-sdk-python-v2/blob/main/samples/shadow_mqtt5.py#L346

[ConorHartin]

Good catch. Although after I called "client.start()" and then "suback = subscribe_future.result(TIMEOUT)", and got the same result.

[MikeDombo]

Did connect succeed? You actually need to be connected before subscribing.

[MikeDombo]

Setup the callbacks for when connecting succeeds so you know what's going on: https://github.com/aws/aws-iot-device-sdk-python-v2/blob/main/samples/shadow_mqtt5.py#L338-L339.

[ConorHartin]

Alright, client.start() hadn't given my any indications of failure before, but when I added methods to log they were being called, I saw it called on_lifecycle_connection_failure 8 times. I'll have to update the logging to see what specifically is causing that.

[jmklix]

If you haven't already tried, I would recommend checking out out mqtt5_pubsub sample. You can run the sample with just this command:

python3 mqtt5_pubsub.py --endpoint <endpoint> --cert <file> --key <file>