In my company we’re using Docker as our standard way of installation for Rocketchat and its MongoDB for our clients.
Recently we have been having problems about the max file descriptors in the MongoDB container; often the application running inside the container surpasses the max file descriptors and the containers crashes.
What I would like to know is:
the maximum file descriptor (hard limit) applies also to the containers or do they have a separate limit?
the total number of open files (lsof | wc -l) launched on the host machine includes the files opened by the containers?
if they are separate, how can we monitor the actual open files for each container (since lsof is not present inside Rocketchat and MongoDB containers)? Is there a way to obtain this metric directly from the host VM for each container, in order to be able to monitor it for example with Zabbix?
Thanks very much