Exposing /dev properly to the container by the Engine

[imrehg]

Description

Udev in containers is major pain. Should have a balenaEngine feature, that exposes the devices dynamically in a container, with just udev running in the host.
The discussion went something like:

When a container is privileged, expose a copy of /dev to the container in a way that they get dynamic devices (and device names), and exposes it to the container in a way that new devices will show up, but the containers cannot create/destroy nodes (just read/write/open the nodes). This would remove most of the needs of users running udev inside the container.

From 2018/12/18 architecture call

Front conversations

[robertgzr]

Something that might be worth looking into for ways to support this natively:

http://marc.merlins.org/perso/linux/post_2018-12-20_Accessing-USB-Devices-In-Docker-_ttyUSB0_-dev-bus-usb-_-for-fastboot_-adb_-without-using-privileged.html

[balena-ci]

[imrehg] This issue has attached support thread https://jel.ly.fish/#/support-thread~3c767d63-31d6-4a63-8681-b4325c0d62f4

[jellyfish-bot]

[srlowe] This issue has attached support thread https://jel.ly.fish/d5b1d2f5-e166-4023-9378-94d718e5d524

[20k-ultra]

We are going to implement this in the Supervisor. See balena-os/balena-supervisor#1532