testcontainers / testcontainers/testcontainers-python

Bug: Segmentation fault when using with confluent kafka consumer

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Dominant language
Python
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Description

Describe the bug

Creating an asyncio test case that uses the kafka container on completion of the test (the test itself is successful) the pytest environment segfaults.

To Reproduce

Provide a self-contained code snippet that illustrates the bug or unexpected behavior. Ideally, send a Pull Request to illustrate with a test that illustrates the problem.

import asyncio
import time
import sys
from confluent_kafka import Consumer
import pytest
from testcontainers.core.waiting_utils import wait_for_logs
from testcontainers.kafka import KafkaContainer

@pytest.fixture(scope="module")
def kafka_container():
    """Provide a temporary Redis container."""
    with KafkaContainer("mirror.gcr.io/confluentinc/cp-kafka:7.6.0") as container:
        wait_for_logs(container, "Awaiting socket connections on 0.0.0.0:9093")
        for topic in ["mytopic"]:
            container.exec(
                f"kafka-topics "
                f"--bootstrap-server localhost:9092 "
                f"--create "
                f"--topic {topic} "
                f"--partitions 3 "
                f"--replication-factor 1",
            )
        yield container

async def kafka_consumer(consumer, timeout=1.0):

    while True:
        msg  = await asyncio.to_thread(consumer.poll,  timeout=timeout)

        if msg is None:
            continue
        if msg.error():
            print("Consumer error: {}".format(msg.error()))
            continue

        print('Received message: {}'.format(msg.value().decode('utf-8')))

async def main(consumer):

    task = asyncio.create_task(kafka_consumer(consumer))

    await asyncio.sleep(10)
    print("Cancelling the task...")
    task.cancel()

    try:
        await task
    except asyncio.CancelledError:
        print("Task was cancelled")

@pytest.mark.asyncio(loop_scope="function")
async def test_sample(kafka_container):
    consumer = Consumer({
        'bootstrap.servers': kafka_container.get_bootstrap_server(),
        'group.id': 'mygroup',
        'auto.offset.reset': 'earliest',
        "debug":"all"})
    consumer.subscribe(['mytopic'])


    await main(consumer)
    consumer.close() 

Runtime environment

Provide a summary of your runtime environment. Which operating system, python version, and docker version are you using? What is the version of testcontainers-python you are using? You can run the following commands to get the relevant information.

[project]
name = "kafka-test"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.13"
dependencies = [
    "confluent-kafka>=2.9.0",
]

[dependency-groups]
dev = [
    "pytest>=8.3.5",
    "pytest-asyncio>=0.26.0",
    "testcontainers>=4.10.0",
]

More info

https://github.com/confluentinc/confluent-kafka-python/issues/1953#issuecomment-2784234429

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the provided test_sample reproduction using KafkaContainer, confluent_kafka.Consumer, asyncio.to_thread, and pytest-asyncio. Review the linked confluent-kafka issue for related context and capture the Python, Docker, testcontainers-python, and dependency versions. Done means the test completes and the pytest environment no longer segfaults.

Written by the indexing model from the issue text.

Assessment

Tech stack
docker, kafka, python
Domain
backend, testing
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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