Deprecate aufs storage driver

[robertgzr]

We currently default to the aufs storage driver for hostapps and balena-engine.

Since moby 19.03 (https://github.com/moby/moby/pull/38090) which the latest balena-engine releases are based off, the aufs storage driver has been marked as deprecated. Additionally, future OS work will actively depend on overlayfs.

These are the currently supported device types that are still running aufs:

• [ ] beaglebone-black
• [ ] fincm3
• [ ] intel-edison
• [ ] intel-nuc
• [ ] npe-x500-m3
• [ ] odroid-c1
• [ ] raspberry-pi
• [ ] raspberry-pi2
• [ ] raspberrypi3
• [ ] raspberrypi3-64
• [ ] revpi-core-3
• [ ] up-board

New device types have for a while been introduced with overlayfs enabled, but we need a migration path for the above device types. Updates to an OS release that switches to overlayfs would require all images to be redownloaded/containers recreated.

To get around that, balena-engine (as of https://github.com/balena-os/balena-engine/pull/168) includes a migration step, which moves the data from one storage driver to the other.

[jellyfish-bot]

[hades32] This issue has attached support thread https://jel.ly.fish/d5d5ad39-98ee-4f13-8772-9c4016ab2b7e

[jellyfish-bot]

[jakogut] This issue has attached support thread https://jel.ly.fish/dcf33c94-9807-42e1-b2be-42c6bd45d64d

[alexgg]

Being deprecated in https://github.com/balena-os/meta-balena/pull/2397