device service usb camera access /dev/video* through docker-compose

[dipshirajput]

Hi All,
I have developed a device service which is specifically for usb camera in order to capture images.
while creating its container, i have defined the following in docker-compose.yml file,

devices:
- /dev/video0:/dev/video0

also tried with the following,

volume:
- /dev/video0:/dev/video0

but still the container is unable to open this port.

please let me know for suggestions. Thanks in advance.

[bnevis-i]

My offhand thought is that /dev/video0 is going to get you access to the screen buffer of your video display, not your USB device.

Look at https://github.com/edgexfoundry/edgex-compose/blob/main/compose-builder/add-device-usb-camera.yml.

    device_cgroup_rules:
      - 'c 81:* rw' # c:character device 81:device major number(81=webcam) *:device minor number rw:read/write
    volumes:
      - /dev:/dev
      - /run/udev:/run/udev:ro

[dipshirajput]

@bnevis-i

1. In my case I am able to capture images with /dev/video0 outside the docker container.
2. If I check inside the container, I am able to see all /dev/video ports after using the volume config you have mentioned.
   but still, inside the container, it shows the following error ,

Error opening video capture device: /dev/video1

please let me know for any suggestions. Thanks.

[bnevis-i]

I have an idea for a few things to try:

• Run your container privileged and see if it works when the container is run privileged. If it does, this probably means that the device cgroup rules are still not right for the container. (the difference between volumes: and devices: is that the devices: line adds cgroup rules that allow the container to access the mapped devices' major and minor numbers).
• Run tools like strace on your binary to see if the program is actually opening files or devices that aren't in the container. Maybe /dev/video* isn't the ONLY thing you need for your program to run
• Make sure you are running with the proper user ID needed to access the devices you are trying to access
• Is your program making any device IOCTLS or system calls that require kernel capabilities that your container doesn't have? (running privileged successfully might also hint at this as well.)

[lenny-goodell]

Why is the EdgeX Device USB Camera service no sufficient for your needs?

[dipshirajput]

we were trying to build a device service for our custom application with features and operation of usb camera a bit different than EdgeX Device USB Camera service

[lenny-goodell]

We would be interest in the different features you need.
If they are applicable to the general community we would welcome your contribution to the EdgeX Device USB Camera service