MergerFS in Docker on macOS?

[BEisem]

I understand that MergerFS does not work on macOS (according to my research ... if this has changed, please let me know!)

So I've been trying to get it to run in Docker on macOS, hoping maybe that would be a workaround.

I got it to work, sort of. I can access the merged directory from within the docker container, if I exec into the container. But the merged directory is empty if I try to access it from the host OS. I can't figure out why this is happening.

Here is the docker run command I'm using:

docker run --rm \
    --init \
    --name=mergerfs \
    --security-opt=apparmor:unconfined \
    -v /Users/bink/mnt/dropbox:/dropbox \
    -v /Users/bink/mnt/feeder:/feeder \
    -v /Users/bink/data/movies:/movies:shared \
    --cap-add SYS_ADMIN \
    --device /dev/fuse \
    ghcr.io/hotio/mergerfs /dropbox:/feeder /movies -o rw,use_ino,allow_other,func.getattr=newest,category.action=all,category.create=ff,cache.files=partial,dropcacheonclose=true,nonempty

As I said, if I exec into the container and go to the /movies directory, it lists the contents of the merged directory. However outside the container, if I go to /Users/bink/data/movies, it is empty.

I realize this isn't directly a mergerfs problem, but I was hoping someone here might have some insight. Any ideas?

[KyleSanderson]

rslave

[BEisem]

I've tried to research this, but still can't get anything to work. I've tried changing the following: -v /Users/bink/data/movies:/movies:rslave \

I also tried --mount type=bind,source=/Users/bink/data/movies,target=/movies,bind-propagation=rslave \

But the results are the same. Can you give me some more insight? Google is failing me at the moment...

[KyleSanderson]

https://docs.docker.com/storage/bind-mounts/#configure-bind-propagation

you could also try shared.

[saltydk]

Tried just mounting /Users/bink/data to /data or something like that and then doing /data/movies?

[ahm99]

Hello,
Any luck solving the issue?

I'm facing the exact same thing
docker compose:

mergerfs:
image: hvalev/mergerfs:latest
container_name: mergerfs
cap_add:
- SYS_ADMIN
devices:
- /dev/fuse:/dev/fuse
environment:
- PUID=501
- PGID=20
volumes:
- /Volumes/NVMe/Docker/mergerfs:/config
- /Volumes/disk1/Data:/disks/disk1
- /Volumes/disk2/Data:/disks/disk2
- /Volumes/disk-3/Data:/disks/disk3
- /Volumes/disk-4/Data:/disks/disk4
- /Volumes/disk-1/Merged:/merged:shared
restart: always

I can see the merged folded in the container terminal with all of the disks contents, and I can see that merged folder is created in may macOS finder, but it's empty

[ahm99]

I tried sharing a volume between containers, actually this is what I want (qbit container to talk to radarr & sonarr containers)
but I see the same thing. the volume doesn't get the merged files and the other containers don't see them. even though if I create a file in a container I can see it in the other and in the volume

in mergerfs container:

/ # ls merged/
Library   Torrents

in other containers:

root@448298d1f591:/# ls merged_data/
test.txt (this is the file I created)

this is my setup:

volumes:
  Merged_Data:
    external: true
    name: Merged_Data

services:
  qbittorrent:
    image: ghcr.io/linuxserver/qbittorrent
    container_name: qbittorrent
    ports:
      - XXXX:XXXX
      - XXXX:XXXX
      - XXXX:XXXX/udp
    environment:
      - PUID=501
      - PGID=20
      - WEBUI_PORT=XXXX
      - TORRENTING_PORT=XXXX
    volumes:
      - Merged_Data:/merged_data:shared
      - /Volumes/NVMe/Docker/qbittorrent:/config
    restart: unless-stopped

  mergerfs:
    image: hvalev/mergerfs:latest
    container_name: mergerfs
    privileged: true
    cap_add:
      - SYS_ADMIN
    security_opt:
      - apparmor:unconfined
    devices:
      - /dev/fuse:/dev/fuse
    environment:
      - PUID=501
      - PGID=20
    volumes:
      - /Volumes/NVMe/Docker/mergerfs:/config
      - /Volumes/disk_1/Data:/disks/disk_1
      - /Volumes/disk_2/Data:/disks/disk_2
      - /Volumes/disk_3/Data:/disks/disk_3
      - /Volumes/disk_4/Data:/disks/disk_4
      - Merged_Data:/merged:shared
    restart: unless-stopped

/ # mergerfs -V
mergerfs v2.40.2-2-gdd987db6

/ # cat /etc/fstab
/dev/cdrom      /media/cdrom    iso9660 noauto,ro 0 0
/dev/usbdisk    /media/usb      vfat    noauto,ro 0 0

/ # df -h
Filesystem                Size      Used Available Use% Mounted on
overlay                 109.7G      4.2G     99.9G   4% /
tmpfs                    64.0M         0     64.0M   0% /dev
shm                      64.0M         0     64.0M   0% /dev/shm
/run/host_mark/Volumes
                        228.3G    204.0G     24.3G  89% /config
/dev/vda1               228.3G    204.0G     24.3G  89% /merged
/run/host_mark/Volumes
                        228.3G    204.0G     24.3G  89% /disks/disk_3
/run/host_mark/Volumes
                        228.3G    204.0G     24.3G  89% /disks/disk_4
/run/host_mark/Volumes
                        228.3G    204.0G     24.3G  89% /disks/disk_1
/run/host_mark/Volumes
                        228.3G    204.0G     24.3G  89% /disks/disk_2
/dev/vda1               109.7G      4.2G     99.9G   4% /etc/resolv.conf
/dev/vda1               109.7G      4.2G     99.9G   4% /etc/hostname
/dev/vda1               109.7G      4.2G     99.9G   4% /etc/hosts
1:2:3:4                 228.3G    204.0G     24.3G  89% /merged

[trapexit]

I'm not surprised that doesn't work. You are created a volume and then in the mergerfs container mounting on top of it. That won't get picked up in different containers let alone what must be a different VM on MacOS. There might be a way to get it to work but that clearly wouldn't be the correct way.

[ahm99]

I'm not sure that I understand what you mean.
my way of thinking is, mergerfs is merging the disks into the volume and the other containers are sharing the same volume

do you have any suggestion that may work?

[trapexit]

Containers have different mount namespaces. You can't mount mergerfs in one namespace and expect it to appear in another. That's not how things work. You don't replace the volume with mergerfs. You mount ON TOP of the volume in the mergerfs container namespace.

[trapexit]

Off hand I don't know how you would set it up or if it is even possible on MacOS. Would have to investigate it.