1.57 seems to cause "Directory already mounted, use --allow-non-empty to mount anyway" error under docker

Suspected Bug
5

There is of course an XKCD for this :wink:

Every bug fixed introduces an potential backwards incompatibility :frowning:

There is an example we can explore in Install

# config on host at ~/.config/rclone/rclone.conf
# data on host at ~/data

# make sure the config is ok by listing the remotes
docker run --rm \
    --volume ~/.config/rclone:/config/rclone \
    --volume ~/data:/data:shared \
    --user $(id -u):$(id -g) \
    rclone/rclone \
    listremotes

# perform mount inside Docker container, expose result to host
mkdir -p ~/data/mount
docker run --rm \
    --volume ~/.config/rclone:/config/rclone \
    --volume ~/data:/data:shared \
    --user $(id -u):$(id -g) \
    --volume /etc/passwd:/etc/passwd:ro --volume /etc/group:/etc/group:ro \
    --device /dev/fuse --cap-add SYS_ADMIN --security-opt apparmor:unconfined \
    rclone/rclone \
    mount dropbox:Photos /data/mount &
ls ~/data/mount

This works fine with v1.57 however if we change it slightly to this then it fails with v1.57 but works with v1.56


# perform mount inside Docker container, expose result to host
mkdir -p ~/data
docker run --rm \
    --volume ~/.config/rclone:/config/rclone \
    --volume ~/data:/data:shared \
    --user $(id -u):$(id -g) \
    --volume /etc/passwd:/etc/passwd:ro --volume /etc/group:/etc/group:ro \
    --device /dev/fuse --cap-add SYS_ADMIN --security-opt apparmor:unconfined \
    rclone/rclone \
    mount dropbox:Photos /data &
ls ~/data

This is is exactly equivalent to the OPs case and seems quite likely people might run into it.

Perhaps we should tighten the /proc/mounts check to refuse only to mount on a fuse filing system, or even maybe just on an rclone fuse filing system?

Rclone mounts look like this

s3:rclone /mnt/tmp fuse.rclone rw,nosuid,nodev,relatime,user_id=1000,group_id=1000 0 0

so perhaps looking for a fuse.rclone might be enough?

I think the error message is perfectly clear - it says the problem and it says which flag to use, so I'm not too worried about that.