Hi there, thanks for your response!
Those Error logs are only from the filebeat containers, which I do not care much for, unfortunately not much error logs there.
It has been quite a challenge to from raw output find the logs I am interested in, as A LOT is logged to /var/lib/docker/containers/*/ 
Autodiscover I haven't tried out yet, I will check that out (will be after christmas, lots to finish before then).
I do have a question: Do you know if the presence of kubernetes metadata has any effect on the functioning of add_docker_meta?