Files within Docker bind mount directory not updating

Question

I am using docker bind mount to map the host /dev/serial/ folder generated by Ubuntu (which contains identifying symlinks to serial devices such as /dev/ttyUSB0). The full docker container run command I am using is

docker run -d --restart always --privileged=true -v /dev/serial:/dev/serial DOCKER_IMAGE_NAME

This works fine at first run, however if the serial device is disconnected and reconnected, the symlinks are recreated. This change does not propagate into the docker container and instead the docker container finds an empty /dev/serial folder. I tested manually creating a file on the host and within the docker container in this directory as well, and strangely the change on one was not updated in the other in both cases.

The volume is shown as

{
    "Type": "bind",
    "Source": "/dev/serial",
    "Destination": "/dev/serial",
    "Mode": "",
    "RW": true,
    "Propagation": "rprivate"
}

EDIT: Ubuntu creates the symlinks within two directories, by-path and by-id underneath the /dev/serial folder.

Answer 1

Bind mounts are based on inodes and when the file is deleted and recreated then the bind-mount is broken. These changes aren't propagated to the bind-mount until a container restart so it picks the new inode.

A solution for this case (files are deleted and recreated) is to mount the parent directory instead, so in your case you can mount using -v /dev:/dev. Of course this will expose /dev to the container so handle it with care.