The intent of finit is to monitor not just processes, but to supervise an entire system and the behavior of certain processes that declare themselves to be finit compliant. Similar to launchd, the goal of finit is to be a replacement for:
- init
- inetd
- crond
- watchdogd
A small and simple replacement, primarily for embedded systems, with a very low dependency on external packages.
-
Add compile-time support for running
/bin/sh
instead ofgetty
-
Add
!
or[wait <pidfile>]
to service directive to let finit pause and wait for a pidfile before starting processes -- both at boot and when starting processes in a runlevel. -
Allow custom reload for processes like libreSwan's pluto
service [2345] <!gw,if:eth0,reload:'starter reload'> /sbin/pluto
-
Allow process callbacks to be scripts.
-
Add support for a pipe/popen where we can listen for
STOP
,START
andRELOAD
onSTDOUT
from a script ... call it for example.monitor=
insvc_t
... the script named as the basename of the service it monitors +.sh
. -
Add support for
/etc/sysctl.d
-
Implement
initctl stop|start|restart|reload|status <SVC>
andservice <SVC> stop|start|restart|reload|status
on top -
Add PRE and POST hooks for when switching between runlevels
-
Make sure to install
queue.h
to$(PREFIX)/include/finit/queue.h
-
Move
finit.conf
"check" command to plugin which checks/etc/fstab
instead. This is the de-facto practice. But keep the check command for really low-end systems w/o/etc/fstab
. -
Add support for generic events (strings or ubus events) that are passed verbatim (?) to the service stanza definitions.
Finit in itself is not SysV Init compatible, it doesn't use /etc/rc.d
and /etc/inet.d
scripts to boot the system. However, a plausible way
to achieve compatibility would be to add a plugin to finit which reads
/etc/inittab
to be able to start standard Linux systems.
Optimize interface filtering by using socket filter. The functions
inet_*_peek()
and inetd_is_allowed()
used for interace filtering
should be possible to rewrite as socket filters.
Requirements are quite rudimentary, basic cron functionality, mainly system-level timed periodic tasks:
- Periodically run a task, in a matching runlevel
- Optionally run as non-root (
crontab -e
as operator)
Proposed syntax:
# Crontab
cron @YY-mm-ddTHH:MM [LVLS] /path/to/cmd [ARGS] -- Optional descr
# One-shot 'at' command
at @YY-mm-ddTHH:MM [LVLS] /path/to/cmd [ARGS] -- Optional descr
Notice the ISO date in notation. The runlevels is extra filtering sugar. E.g., if cron service is only allowed in runlevels two or three it will not start if system currently is in runlevel four.
To run a command as another user the .conf
file must have a that
owner. E.g., /etc/finit.d/extra.conf
may be owned by operator and
only hold cron ...
lines.
What would be extremely useful is if initctl
, or a homegrown at
,
could support the basic functionality of the at
command directly from
the shell -- that way setting up one-time jobs would not entail
re-reading /etc/finit.conf
Support for monitoring the health of the system and its processes.
- Add support for a
/dev/watchdog
built-in to replace both the BusyBox watchdogd and my own refreshed uClinux-dist adaptation, watchdogd - Add a system supervisor (pmon) to optionally reboot the system when a
process stops responding, or when a respawn limit has been reached, as
well as when system load gets too high. For details on UNIX loadavg,
see http://stackoverflow.com/questions/11987495/linux-proc-loadavg
- Default to 0.7 as MAX recommended load before warning and 0.9 reboot
- API for processes to register with the watchdog, libwdt
- Deeper monitoring of a process' main loop by instrumenting
- If a process is not heard from within its subscribed period time reboot system or restart process.
- Add client libwdt library, inspired by old Westermo API and the
libwdt API published in the Fritz!Box source dump, take for
instance the
fritzbox7170-source-files-04.87-tar.gz
drop and see theGPL-release_kernel.tgz
indrivers/char/avm_new/
for the kernel driver, and theLGPL-GPL-release_target_tools.tgz
inwdt/
for the userland API. - When a client process (a standard app/daemon instrumented with libwdt calls in its main loop) registers with the watchdog, we raise the RT priority to 98 (just below the kernel watchdog in prio). This to ensure that system monitoring goes before anything else in the system.
- Use UNIX domain sockets for communication between daemon and clients
- Separate
/etc/watchdog.conf
configuration file, or a perhaps support for a more generic/etc/finit.d/PLUGIN.conf
? - Support enable/disable watchdog features:
- Supervise processes,
- CPU loadavg,
- Watch for file descriptor leaks,
- etc.
- Write man pages for finit and
finit.conf
, steal from the excellentpimd
man pages ... - Update Debian
finit.conf
example with runlevels,tty/console
and dependency handling for Debian 8 (the dreaded systemd release).
- FHS changes affecting runtime status, plugins, etc.