Re: rcd(8) - new service manager daemon

On Sun, 14 Jun 2026 21:36:08 +0200
Céleste Ornato <[email protected]> wrote:

> Hi,
> 
> This is honestly great! I must admit the long bootup times - while
> *fine* - have always been kind of annoying, and having something
> backwards-compatible that improves on that (and, I assume, is generally
> more modern) is very appealing to me. I will be testing it ASAP.
> 
> Do you have an estimate as to how much time is saved from specifically
> the parallelisation?

Presumably not many. My patches for /bin/sh were eccepted in 2013 when I've
used them to add `-p` flag to rcorder to give lists of scripts before barriers
to be started parallel. I gave up on it when found it does not give much speed
up, probably because synchronization needed for barriers anyway. Later years
where attempts from others to teach `rcorder` and that lead to nothing
official, probably due to same reasons.

What is interesting in this project is not that parallel boot but that it
brings us *good* parts of systemd without it's *bad* parts (hopefully :) did
not look at code but description looks promising and at least it avoids systemd
error of being PID 1). For example, seems the many-years voices blaming of
sshd(8) being dependent on LOGIN instead of started as early as possible to
make remote server accessible (thus repairable!) if something goes bad later in
boot process, now can just tweak dependency in configuration of units (instead
of patching hardcoded values which every OS update will rewrite).

Using UCL is also much more better than systemd's ancient INI-shitstyle format
of units, pdfork/procctl/other FreeBSD-native interfaces much more better
than ugly systemd's requirement for service to not fork and leave stderr fd
pointing to daemon, and so on etc.
 
> Baptiste Daroussin <[email protected]> writes:
> 
> > Hello everyone
> >
> > I have been working for the past years on rcd(8), a new service manager
> > daemon for FreeBSD, some of you might recall a presentation in french 15
> > years ago or some discussion in BSDcam also that old!
> > I would like to start a discussion about its integration into the tree.
> >
> > What is rcd?
> >
> > rcd(8) is a service manager daemon called by init(8) (in place of
> > /etc/rc).  It reads service definitions from UCL unit files
> > (/etc/rcd.d/*.ucl), builds a dependency DAG, and starts services in
> > parallel.  After boot completes, it forks to background and stays
> > running as a supervision daemon (automatically restarting failed
> > services and accepting control commands via a UNIX socket).
> >
> > Key features:
> >
> >   - Parallel boot via dependency DAG (no more serial rc.d execution)
> >   - Process tracking via pdfork(2) descriptors (no PID file races)
> >   - Subreaper via procctl(2) (no orphaned process escape)
> >   - Socket activation (pre-bound sockets passed via fd inheritance)
> >   - Resource control per service via rctl(2)
> >   - Service isolation via native jail(2) integration
> >   - OOM protection via procctl(2) PROC_SPROTECT
> >   - UCL-based unit files (JSON Schema validated)
> >   - Embedded Lua interpreter for inline service hooks
> >   - Template units for per-instance services (e.g., dhclient@em0)
> >   - Safe in-place binary upgrade (SIGUSR1: save state, re-exec)
> >   - Per-service access control on the control socket
> >   - Suspend/resume support
> >
> > User interface: rcctl(8)
> >
> > Service management is done via rcctl(8):
> >
> >     rcctl start sshd
> >     rcctl enable sshd
> >     rcctl restart dhclient@em0 netif@em1
> >     rcctl status
> >     rcctl show nginx
> >
> > 100% backward compatibility
> >
> > This is a hard requirement: rcd must work on existing FreeBSD systems
> > without modifying any rc.d scripts or configuration files.  Here is how
> > this is achieved:
> >
> >   1) rcd scans /etc/rc.d/ and /usr/local/etc/rc.d/ for existing
> >      rc.d scripts, parses their PROVIDE/REQUIRE/BEFORE/KEYWORD headers
> >      (same format as rcorder(8)), reads rc.conf(5) to determine the
> >      enabled state, and wraps each script as a virtual "legacy" unit
> >      in the dependency graph.
> >
> >   2) Legacy scripts are auto-classified during loading:
> >      - Scripts with pidfile= or command= -> "legacy-forking" units,
> >        tracked by rcd-exec(8) sub-reaper without pidfiles.
> >      - Scripts with only comments/blank lines -> barrier units.
> >      - Scripts without rcvar= are always enabled.
> >
> >   3) All rcctl(8) commands are passed through to the script directly:
> >          rcctl reload sshd -> /bin/sh /etc/rc.d/sshd reload
> >
> >   4) Template instances preserve the traditional calling convention:
> >          rcctl restart netif@em0 netif@em1  
> >          -> /bin/sh /etc/rc.d/netif restart em0 em1  
> >
> >   5) rcd reads /etc/defaults/rc.conf, /etc/rc.conf and
> >      /etc/rc.conf.local to determine legacy service enablement.
> >
> > The result: you can install rcd on a running system, reboot, and
> > everything works exactly as before -- except boot is faster because
> > services start in parallel where the dependency graph allows.
> >
> > Current status and what I need
> >
> > I would like to commit this to main soon so that people can start
> > testing it on their machines.  The initial commit will include:
> >
> >   - sbin/rcd/   -- the daemon, rcd-exec helper, unit tests
> >   - sbin/rcctl/ -- the control utility
> >   - Man pages: rcd.8, rcctl.8, rcd.conf.5, rcd.d.5, rcd-lua.3,
> >     rcd-exec.8
> >
> > It will NOT change init(8) or /etc/rc yet.  rcd will be built and
> > installed but not activated by default.  To test, you will be able to
> > run it manually or configure via kenv(8) to replace /etc/rc.
> >
> > Migration path
> >
> > The plan for a smooth transition:
> >
> > - 1 (now): Commit rcd(8) and rcctl(8) to the tree.  Build by
> >   default, but not activated.  Early adopters can test.
> >
> > - 2 (later): Commit init(8) changes to call rcd when present (falling
> >   back to /etc/rc otherwise).  Provide a /etc/rc wrapper that invokes
> >   rcd for systems that want to switch.
> >
> > - In the meantime: convert base system rc.d scripts to native
> >   UCL unit files adding the norcd keywords to the rc.d so that they
> >   are not read anymore by rcd(8).
> >
> > - Ultimately: rc.d -> unit files, at the pace each maintainer sees fit.
> >   There is no deadline; rc.d scripts are supported as long as needed.
> >
> > The code lives there:
> > https://reviews.freebsd.org/D56835
> >
> > Baptiste  
> 



-- 
WBR, @nuclight