docker-py/docs/host-devices.md

Access to devices on the host

If you need to directly expose some host devices to a container, you can use the devices parameter in the Client.start method as shown below

c.start(container_id, devices=['/dev/sda:/dev/xvda:rwm'])

Each string is a single mapping using the colon (':') as the separator. So the above example essentially allow the container to have read write permissions to access the host's /dev/sda via a node named /dev/xvda in the container. The devices parameter is a list to allow multiple devices to be mapped.