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Accessing devices

Overview​

When running containerized applications, some services may need direct access to hardware devices such as USB drives, serial ports, or GPUs. Docker allows containers to use host devices through the devices directive in a docker-compose.yaml file. In this tutorial, we will explore how to configure device access in Docker Compose and go through a practical example using the Filebrowser image.

Configuring Device Access in docker-compose.yaml​

Setting Permissions for Device Access​

Before granting access to a device, ensure that the container has the necessary permissions. You may need to adjust the device’s permissions using the following command:

sudo chmod 666 /dev/sda1

Alternatively, you can add the container to a user group with appropriate access rights:

sudo usermod -aG disk $(whoami)

This ensures that the containerized application can read and write to the device properly.

Docker provides the devices option to pass host devices into containers. This is useful when an application needs direct communication with a specific hardware component.

Example Configuration​

The following docker-compose.yaml file demonstrates how to allow a Filebrowser container to access a USB storage device:

version: '3.8'

services:
  filebrowser:
    image: filebrowser/filebrowser:latest
    ports:
      - "8080:80"
    volumes:
      - /mnt/usb:/srv
    devices:
      - "/dev/sda1:/dev/sda1"

Explanation:​

  • Volumes:
    • - /mnt/usb:/srv: Mounts the USB drive into the container at /srv so that Filebrowser can access its contents.
  • Devices:
    • - "/dev/sda1:/dev/sda1": Grants the container direct access to the USB device located at /dev/sda1 on the host system.

Summary​

By specifying device access in the docker-compose.yaml file, you can allow containers to interact with hardware components such as USB storage, serial devices, or GPUs. This is essential for applications that require direct hardware communication in a containerized environment.