How to see python logging output from child docker container (container started by another container)?

Question

I have an application that uses docker compose to start 3 containers. The logs for those 3 containers are outputted to stdout as expected. One of these containers is responsible for starting other containers, as they are needed. It uses docker-py to do that.

Those secondary containers are ephemeral, they run until the task is done and terminate. However I can't see their logging output.

• When I started, the docker-compose containers also weren't outputting logging to stdout, I had to use the following configs both in Dockerfile and the code:

self.logger = logging.getLogger(__name__)
level = logging.INFO
stream_handler = logging.StreamHandler(sys.stdout)
self.logger.setLevel(level)
formatter = logging.Formatter("%(asctime)s - %(name)s [%(levelname)s]: %(message)s")
stream_handler.setFormatter(formatter)
self.logger.addHandler(stream_handler)

Dockerfile

ENV PYTHONUNBUFFERED=1 

Now, I've tried to add the same settings in the code and Dockerfile for my secondary containers, this time though, it made no difference. It's possible that I may need to pass further instructions to docker-py when running the containers.

network = self.docker_client.networks.get("service-daemon_default")
_ = self.docker_client.containers.run(
    image="default_image",
    detach=True,
    environment={
        "VENDOR_NAME": vendor,
        **self.settings.get("environment"),  # These are just REDIS configs, such as host, port , etc
    },
    name=vendor.lower(),
    network=network.name,
    auto_remove=self.settings.get("auto_destroy_containers", True),
)