Instance persistent storage

Apps and Virtualization
1

I am creating a container, that seems all good. Example; creating a container using Ubuntu 24.04 and running updates, install openssh-server and other apps. If I want to add a disk for persistent storage that is where I am running into an issue and am unable to find documentation or and example of what the permissions for that dataset should be. I can add it, it seems to be read only and inside the container it is owned by nobody:nogroup

root@Docker:~# ls -l /mnt/
total 1
drwxr-xr-x 2 nobody nogroup 2 Mar 22 20:29 data

I am unable to change owner in the container unable to write to it etc…

I’d be greatful for a hint.

Fangtooth Discussion Thread
2

Found some information here:

It appears when mounting disks to a container in Incus it needs to be set to use shiftfs

Setting this on the host at the cli at least gave ownership to root. The truenas UI needs to be able to handle this setting for this usage to work properly.

incus config device set Docker disk0 shift=true

root@truenas[~]# incus config show Docker --expanded            
architecture: x86_64
<truncated output>
config:
devices:
  disk0:
    path: /mnt/data
    shift: "true"
    source: /mnt/ssd-storage/Multi-docker
    type: disk

root@Docker:~# ls -l /mnt/
total 1
-rw-r--r-- 1 root root 0 Mar 24 23:39 1
drwxr-xr-x 2 root root 3 Mar 24 23:39 data
root@Docker:~# ls -l data/
ls: cannot access 'data/': No such file or directory
root@Docker:~# ls -l data
ls: cannot access 'data': No such file or directory
root@Docker:~# ls -l /mnt/data
total 1
-rw-r--r-- 1 root root 0 Mar 24 23:39 testfile
3

This is not recommended. See documentation in RC1 release notes about userns idmapping.

4

all i see i the release notes is:

Full IDMAP support is currently unavailable in the TrueNAS UI (NAS-134447). Users testing instances in 25.04-RC.1 can use the apps user and group (568:568) to set permissions with consistent mapping in the TrueNAS host and containers.

does this mean when i use shift=true if a dataset is not owned by apps it wont work?

im having issues using shift=true on nested datasets where all ownership is apps which according to the notes should be working?

5

Did you notice that the fix version for that bug ticket was 25.04.0?

1 Like
6

ah sorry about that. i should have checked the updates notes. thanks!

7

Hi all. Trying to do the same in an instance, mounting a dataset to it and accessing from within. Here are some screenshots of how I have set it up:

image
image1291×913 27 KB

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image2166×652 37.6 KB

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image1612×1105 43.4 KB

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image2059×619 24.1 KB

Within my instance, I have created a user with the same UID/GID:
image

When I view permissions on the mount in TrueNAS:
image

When I do the same from within my instance:
image

Which is nobody nogroup.

@awalkerix any thoughts on why this could be, and how I can get access to the disk within my instance?

8

After rebooting TrueNAS the idmap was correct. Not sure exactly what service restart was required. Restarting the instance was not sufficient.

1 Like