Description

(Enhancement suggestion; addition to work done in #506 )

While doing some testing, I tried using a generated group id to easily get messages from the beginning:

consumer = Consumer({
    "bootstrap.servers": "my-server",
    "security.protocol": "SASL_SSL",
    "sasl.mechanisms": "PLAIN",
    "sasl.username": "my-username",
    "sasl.password": "my-password",
    "group.id": uuid4()
})

I forgot to str the UUID. Passing a non-string group id allowed the Consumer to be created and polled without error but never returned any messages. Calling str on the UUID fixed it like: str(uuid4()).

The code modified in PR #506 could be further modified to apply the PyObject_Str function to coerce the group.id to a string or a type check to confirm it is a string (raise error if not) before passing the value onto the underlying C library.

In my case, a PyObject* referring to a uuid.UUID was passed to librdkafka and undefined behavior happened.

How to reproduce

Try polling from a topic using a non-string group.id like the code above. poll should timeout every time, returning None.

Checklist

Please provide the following information:

• confluent-kafka-python and librdkafka version (confluent_kafka.version() and confluent_kafka.libversion()):
  • confluent_kafka.version() = ('1.7.0', 17235968)
  • confluent_kafka.libversion() = ('1.7.0', 17236223)
• Apache Kafka broker version:
  • using Confluent Cloud
• Client configuration: {...}
  • example given above
• Operating system:
  • Windows 10
• Provide client logs (with 'debug': '..' as necessary)
• Provide broker log excerpts