How to deal with permissions for USB devices

[ddt3]

I am running a docker in flatcar (on proxmox) that uses a zigbee USB device. User running docker is core

$ lsusb
Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 1a86:55d4 QinHeng Electronics SONOFF Zigbee 3.0 USB Dongle Plus V2
Bus 003 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub

$ ls -al /dev/serial/by-id/usb-ITEAD_SONOFF_Zigbee_3.0_USB_Dongle_Plus_V2_20231008154809-if00 
lrwxrwxrwx. 1 root root 13 Jan 19 14:22 /dev/serial/by-id/usb-ITEAD_SONOFF_Zigbee_3.0_USB_Dongle_Plus_V2_20231008154809-if00 -> ../../ttyACM0

I can only get the USB device to work if I change the group ownership of ../../ttyACM0 to group core.
Now I would like to create an ignition file (or actually a butane file) how would I do that?

I already tried adding user core to group tty but it appears the device is created with group ownership dailout, a group that does not exist on flatcar (yet is shown in ls -al):

$ getent group tty
tty:x:5:
 $ getent group dailout
 $ ls -al /dev/tty*
<SNIP>
crw--w----. 1 root tty       4, 60 Jan 19 14:22 /dev/tty60
crw--w----. 1 root tty       4, 61 Jan 19 14:22 /dev/tty61
crw--w----. 1 root tty       4, 62 Jan 19 14:22 /dev/tty62
crw--w----. 1 root tty       4, 63 Jan 19 14:22 /dev/tty63
crw--w----. 1 root tty       4,  7 Jan 19 14:22 /dev/tty7
crw--w----. 1 root tty       4,  8 Jan 19 14:22 /dev/tty8
crw--w----. 1 root tty       4,  9 Jan 19 14:22 /dev/tty9
crw-rw----. 1 root core    166,  0 Jan 19 14:22 /dev/ttyACM0
crw-------. 1 core tty       4, 64 Jan 19 14:22 /dev/ttyS0
crw-rw----. 1 root dialout   4, 65 Jan 19 14:22 /dev/ttyS1
crw-rw----. 1 root dialout   4, 66 Jan 19 14:22 /dev/ttyS2
crw-rw----. 1 root dialout   4, 67 Jan 19 14:22 /dev/ttyS3
crw-------. 1 root root      5,  3 Jan 19 14:22 /dev/ttyprintk

So how can I solve this using butane?

[tormath1]

Hello @ddt3,

Did you have a look to those examples: https://www.flatcar.org/docs/latest/setup/customization/adding-users/#add-users-via-butane-configs ?

This configuration should add the core user to the dialout (use tty if you want tty) group:

variant: flatcar
version: 1.1.0
storage:
  files:
    - path: /etc/userdb/core:dialout.membership
      contents:
        inline: " "

Please note the typo in your initial message too - dialout vs dailout:

$ getent group dialout
dialout:x:249:

[ddt3]

I think my typo is the root cause of everything!
I actually created a butane with this information:

variant: flatcar
version: 1.0.0
passwd:
  users:
    - name: core
      ssh_authorized_keys:
        - "ssh-rsa <snip>"
      groups:
        - tty 
        - daillout
        - docker

(with the same typo)
Maybe I should clean my glasses more often

I will change the above and instead create a userdb file

Thanks @tormath1 ! Sorry for wasting your time...

[tormath1]

Perfect, I am happy you solved the issue and you did well to open a discussion for this.

For what is worth, userdb is a more modern approach for handling users and groups on Linux distributions. You can choose whatever approach that fits the most for your need.

Do not hesitate to join the next Flatcar office hours if you want to present your Flatcar / Proxmox / Zigbee experimentations: #1606

Feel free to close the issue and/or mark my comment as "answer" to your initial request. :)

[ddt3]

@tormath1 I have it up and running now thanks again! My scripts and Butane files can be found here:
https://github.com/ddt3/proxmox-flatcar