Kafka consumer script hangs when executed as a docker entrypoint

Question

I am trying to connect a python kafka consumer to a kafka broker using the following script:

import kafka

from configuration import config


if __name__ == "__main__":

    print('Start')

    consumer = kafka.KafkaConsumer(
        bootstrap_servers=config.KAFKA_BOOTSTRAP_SERVERS,
        auto_offset_reset =config.CONSUMER_AUTO_OFFSET_RESET,
        enable_auto_commit=True,
        group_id=None,
    )
    consumer.subscribe((config.CONSUMER_INPUT_TOPIC,))

    print('Listening')
    for msg in consumer:
        print('Message received')

I am executing that script as an entrypoint to a custom docker image.

This script works fine when executed from my local shell with python script.py or even when I execute it manually through docker using docker-compose exec my_service python script.py but it does not run at all when executed through the entrypoint. In the latter case not even the Start is printed! One more detail is that when for msg in consumer: block is removed the script gets executed and the prints show up.

I have tested it in two pc's and received the same results.

I have tried with the following python base images:

python:3.8.5
python:3.8.13
python:3.8.13-slim-buster

The output of docker inspect <custom_image_name> | grep -A5 Cmd is:

            "Cmd": [
                "/bin/sh",
                "-c",
                "#(nop) ",
                "ENTRYPOINT [\"sh\" \"/entrypoint.sh\"]"
            ],
--
            "Cmd": null,
            "Image": "sha256:<sha256>",
            "Volumes": null,
            "WorkingDir": "",
            "Entrypoint": [
                "sh",

My Dockerfile:

FROM python:3.8.13-slim-buster

COPY ./resources/requirements.txt /requirements.txt

RUN pip install pip --upgrade \
    && pip install -r /requirements.txt

COPY ./resources/entrypoint.sh /entrypoint.sh

ENTRYPOINT ["sh", "/entrypoint.sh" ]

and the entrypoint.sh

#!/usr/bin/env bash

python run.py