Thursday, October 27, 2022

[SOLVED] Rootless podman: use nfs mount

Issue

i found this question first which is similar: How to mount an NFS share with rootless Podman?

long story short i am having trouble with rootless podman nfs volume. i am creating the volume with myuser

podman volume create --opt type=nfs4 --opt o=rw --opt device=my.server.ip.address:/data/nfs_data podman-nfs

but when trying to spawn a container using the volume i get a "mount.nfs: operation not permitted"

podman run -d -v podman-nfs:/tmp/data --name myapp myappimage:latest

i know that the nfs mount works because i managed to make it work manually. i used the user directive in fstab to allow myuser to mount it manually. i even managed to mount it manually in the path generated by podman (/home/myuser/.local/share/containers/storage/volumes/podman-nfs/_data)

the fstab entry looks like :

my.server.ip.address:/data/nfs_data /home/myuser/.local/share/containers/storage/volumes/podman-nfs/_data nfs rw,sync,user,noauto,_netdev 0 0

i could revert to a regular nfs mount on the filesystem and have podman use it like a file but i like the idea of having nfs managed by podman so it can gracefully close it if the container stops.

ADDITIONAL INFO : if i try using the --log-level=debug flag in podman run i get 'mount /bin/mount [...] failed with exit status 32'

as a side note i find it very weird that you can create volumes as a rootless podman user but cannot mount them. it feels like i'm missing something obvious. i found this howto which does it as root https://www.server-world.info/en/note?os=Rocky_Linux_8&p=podman&f=6

thank you for your time.


Solution

Me again.

I've figured it out. My understanding is that rootless podman cannot mount an NFS volume when starting a container even if the fstab has the user option for the mount.

Instead, what i do is during my ansible playbook as root i mount the nfs mount to a mountpoint (for this example, /app/myapp/myapp-nfs) and i use a bind mount when starting the container.

first make sure the nfs is properly mounted on the filesystem

# src must be accessible by nfs
- name: Make sure nfs is mounted
  ansible.posix.mount:
    src: nfs.ip.address.here:/shared/nfsdir
    path: /app/myapp/myapp-nfs
    opts: rw,sync,hard,_netdev
    boot: yes
    state: mounted
    fstype: nfs
  become: yes

second when starting the container use the available nfs as a bind mount

# src must be accessible by nfs
- name: Make sure my nfs-enabled-elite-app is started
  containers.podman.podman_container:
    name: nfs-enabled-elite-app
    image: elite-app:latest
    state: started
    mounts:
      - type=bind,source=/app/myapp/myapp-nfs,destination=/in/container/mount/point

so far this works.

note that you can all do this using the podman run command, just add the mount (NOT as a volume)

i really hope this gets to help people. i remain available in case you have any question just DM me.



Answered By - Quardah
Answer Checked By - Willingham (WPSolving Volunteer)
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