finit/TODO.md

Goals of Finit

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.

General

• Add halt/poweroff/shutdown symlinks to finit and convert reboot, but only install symlinks if these tools don't already exist.
• Add support for timed shutdown in Finit, including cancelled shutdown.
• SysV init and systemd use SIGUSR1 to restart their FIFO/D-Bus. Add API restart to SIGHUP callback for the same functionality in Finit.
• Add finit.conf support for UPS notification (SIGPWR) to start a task using, e.g. <sys/power/{ok,fail,low}> conditions. More info in sig.c
• Add finit.conf support for ctrl-alt-delete (SIGINT) and kbrequest, i.e. KeyboardSignal, (SIGWINCH) behavior. Using conditions to a task, e.g, <sys/key/ctrlaltdel> and <sys/key/signal> like SIGPWR handling.
• Add IFF_RUNNING support to netlink plugin along IFF_IUP
• Allow process callbacks to be scripts.
• Add support for a pipe/popen where we can listen for STOP, START and RELOAD on STDOUT from a script ... call it for example .monitor= in svc_t ... the script named as the basename of the service it monitors + .sh.
• Implement initctl stop|start|restart|reload|status <SVC> and service <SVC> stop|start|restart|reload|status on top
• Add support for JSON output, or similar, from initctl show, e.g. initctl show --json
• Improve initctl show SVC output. Add service uptime, last ten SVC logs/history (historian), etc. Similar to systemctl show SVC
• Add PRE and POST hooks for when switching between runlevels

Init

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.

Inetd

• Add support for throttling connections.
• 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.
• Optimize HTTP/HTTPS inetd connections by adding basic support for the inetd variant redir http/tcp@eth0 nowait [2345] 127.0.0.1:8080, which would reduce the overhead of spawn the web server on each HTTP connection, yet still provide a means of filtering access per iface.

Crond

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

Documentation

• Write man pages for finit and finit.conf, steal from the excellent pimd man pages ...
• Add simple, very simple, finit-simple.conf example. To illustrate how close Finit3 still is to the original easy-to-use Finit0 :)