/dev/dri/renderD128 now owned by "render" group, plex missing permission

[lutzky]

Expected Behavior

On a device with quicksync, if /dev/dri is correctly mapped, Plex should use hardware encoding. To accomplish this, Plex should have access to /dev/dri/renderD128.

Current Behavior

$ cat /etc/lsb-release 
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=19.10
DISTRIB_CODENAME=eoan
DISTRIB_DESCRIPTION="Ubuntu 19.10"
$ ls -l /dev/dri
total 0
drwxr-xr-x  2 root root         80 Nov 19 22:06 by-path
crw-rw----+ 1 root video  226,   0 Nov 19 22:06 card0
crw-rw----+ 1 root render 226, 128 Nov 19 22:06 renderD128

Note that renderD128 is owned by group render, not video. New in ubuntu 19.10, I think :/. Plex container doesn't identify that:

$ docker exec plex ls -l /dev/dri
total 0
crw-rw---- 1 root video 226,   0 Nov 19 22:28 card0
crw-rw---- 1 root   109 226, 128 Nov 19 22:28 renderD128

Resultingly, plex fails to access the device, yielding this error in the logs:

Nov 19, 2019 22:31:40.052 [0x7fea17fff700] DEBUG - Codecs: testing h264 (decoder) with hwdevice vaapi
Nov 19, 2019 22:31:40.052 [0x7fea17fff700] DEBUG - Codecs: hardware transcoding: testing API vaapi
Nov 19, 2019 22:31:40.052 [0x7fea17fff700] DEBUG - Codecs: hardware transcoding: opening hw device failed - probably not supported by this system, error: Generic error in an external library

Workaround:

sudo chgrp video /dev/dri/renderD128
docker restart plex

Steps to Reproduce

See above.

Environment

OS: Ubuntu 19.10
CPU architecture: x86_64
How docker service was installed:
http://github.com/lutzky/wamc

Command used to create docker container (run/create/compose/screenshot)

http://github.com/lutzky/wamc has my full docker-compose.yml

Docker logs

Relevant snippets shown above.

[lutzky]

Note, the above workaround does not survive a reboot. To make it permanent, modify /lib/udev/rules.d/50-udev-default.rules, replacing GROUP="render" with GROUP="video".

[aptalca]

It doesn't look like you're using our image. Our image adds the abc user inside the container to all of those groups including render and video via this script: https://github.com/linuxserver/docker-plex/blob/master/root/etc/cont-init.d/50-gid-video

[j0nnymoe]

https://github.com/lutzky/wamc/blob/master/docker-compose.yaml#L6

Yea you aren't using out container, You need to post this over at the plex forums.

[lutzky]

Well, that's embarrassing. Thanks for pointing out your script that fixes it, it's quite elegant!