NodeOS-init is a simple init that only reap zombie processes and shutdown the system when there's no more running ones. It was initially based on sinit, at the same time based on Rich Felker's minimal init.
NodeOS is an operating system build entirely on Node.js, and also it was its
PID 1 init process (century).
Problem is, on v0.11.15 Node.js upgraded the version of v8 from v3.26.33 to
v3.28.73, and a regression was introducced that don't allow to use it as PID 1
anymore, seems related to the need of having a devtmpfs filesystem mounted on
/dev and not only defined a /dev/console device file. Due to this, we need
to mount it previously to any instance of Node.js can be executed, but also we
can this way control better the processes termination and cleanly shutdown the
system instead of get a Kernel panic. It will also mount the procfs
filesystem at /proc since it's heavily needed by musl.
There are 4 signals that NodeOS-init will act on.
- SIGCHLD: reap children
- SIGINT: reboots the machine (or alternatively via
ctrl-alt-del) - SIGTERM: send the
SIGTERMto all its child processes and later shutdown - SIGALRM: countdown. There are remaining child processes after sending them
the
SIGTERMsignal and it has elapsed 5 seconds since the last one was reap, send theSIGTERMto them and later shutdown
It also cleanly shutdown the machine by syncing disks and unmounting the working filesystems when it detect there are no more child processes running on the system.