'YInit' is designed to boot on bare-metal and in containerized environment. As in containerized environment host OS already provides multiple sub-systems, 'YInit' is only required to bring up container-specific services.

Services provides functions. Targets represent specific boot state. Instances represent service performance.

init:

• devfs [oneshot or daemon]: mount - devfs, sysfs and procfs
• hwclock [oneshot]: set a hardware clock
• console [daemon]: set console

launch

• localmount [oneshot]: check and remount rootfs to 'rw', check and mount remaining filesystems.
• storagemaintenace [periodic]: check and maintain filesystems – fstrim, BtrFS scrub
• hostname [oneshot]: set the hostname

network

• firewall [oneshot]: set rules
• network manager [daemon]: start network manager
• netmount [oneshot]: mount network filesystems

netowork.online

• ntp [daemon]

system

• sshd [daemon]
• nfs server

user

• getty [daemon]

oneshot – run coresponding process once at launch and optionally once at shutdown. periodic – run coresponding process according to scheduler deamon – run process as daemon

Each service run by YInit belongs to a specific target, the following targets are defined:

1. init – Does initialization of the following special filesystems: devfs, procfs, sysfs.
2. launch – Checks and mounts root and user filesystems, loads drivers, sets up hardware settings, launches logging capability.
3. network – Initializes network via ConnMan and firewall.
4. network.online – Brings up network services that require WAN access: NTP client. Successful pass of this target indicates that the machine is considered to be online.
5. system – Starts system services such as SSH server and other.
6. user – Runs user related services: login manager, task scheduler and other.

YInit ensures to start all active services for a specific target regarding to defined service dependencies.

The default target to achieve is 'user' (6), targets are executed in the order show above (that is: init, launch, network, network.online, system, user).

Target 'user' is the state of the OS that provides all user desired services. Targets from 1 to 4 are bare-metal specific, in containerized environment these are to be provided by host OS. Targets 5 and 6 are common for bare-metal and containerized environments – these are responsible for launching services specified for a given computer/VM.

To ensure proper system boot and shutdown services must start and stop in a proper order.

This can be defined by defining the following relations per service:

after = serviceX,targetX

before = serviceX, targetZ

wants = service

requires = service