2019-10-13 afbjorklund

Containers on ARM

Now half-way through Hacktober, and again revisiting the task of running containers on the Raspberry Pi (which is using ARM CPU) instead of the usual x86_64 virtual machine.

The initial focus is on the 32-bit models (armv6l and armv7l), with the 64-bit version (aarch64) coming later. Currently a bit unstable, but has a lot of interest server-side.

Hardware

Here is a short summary of the available models of Raspberry Pi:

#	Arch	Bits	CPU	RAM
0	armv6	32-bit	x 1	512M
1	armv6	32-bit	x 1	512M
2	armv7	32-bit	x 4	512M
3	armv7	64-bit	x 4	1G
4	armv8	64-bit	x 4	1-4G

See also https://en.wikipedia.org/wiki/Raspberry_Pi for details.

QEMU

Linux has a feature binfmt_misc, which allows the kernel to start a program using any interpreter - such as for instance qemu-arm.

This allows us to run armv6 containers on a regular x86_64 kernel. Unfortunately it is a bit unstable, especially with Go programs…

piCore

Tiny Core Linux has a version for the Raspberry Pi called “piCore”. The 9.x version has been released, but the 10.x is still in “beta”.

http://www.tinycorelinux.net/9.x/armv6

This allows building an image, including qemu-arm-static for the older kernels, as well as the armv6 rootfs from the piCore initramfs:

https://github.com/boot2podman/boot2podman/tree/master/containers/tinycore-arm

Podman

The current work is about building a piCore with the features that are required to run containers (cgroups and overlayfs).

Completed so far is building a Go compiler and building the packages with the required software (like conmon and runc).