When you have installed CoreELEC, mounted your NAS/Samba with music-collection, and would like to add volumio
But CoreELEC does not have a package manager and can not add nodejs which is required to server volumio.
Luckily, you can untar an archlinuxarm rootfs on /storage/alarm, then you can mount bind proc sys and chroot into it, there you can do normal pacman -S nodejs and install and configure volumio.
Another option is to not use archlinuxarm but just extract the squashfs of volumio and use it as chroot, run the volumio services - CoreELECs systemd can do containerization. Sweet. You only need to let volumios pulse speak to CoreELECs pulse.
Next up, you write a systemd service file and place it in /storage/.config/system.d/volumio.service
and in a systemd service you can say “use this chroot please and restrict its fs view to /storage/alarm”
How awesome isnt this! You can run any rootfs from CoreELEC, and by writing a systemd service, have it start on boot and be managed by systemd as normal.
But wait there is more. In the volumio.service on CoreELEC host, you can also specify CPU and Memory Limits to apply - to never let nodejs/volumio hog up or lag the hosts kodi.bin process.