Re: Status of OpenRC in Debian (was: Debian systemd survey)
On 05/24/2013 02:19 PM, Svante Signell wrote:
> What is the status of packaging OpenRC for Debian? Is there a group
> doing that, is help needed?
Ok, if you ask...
Currently, the package can build and install, at least on Linux flavors
of Debian.
Once installed, it will unfortunately not understand the LSB headers of
the scripts in /etc/init.d. I tried replacing the init script provided
by the source package of sysvrc by the one shipped with OpenRC (they are
called "runscript), and it worked very well. For fun, I replaced the LSB
headers of essential boot init.d scripts (I tried with udev and ssh),
and it just worked out of the box. I had "rc-status" working, together
with the cgroups support (which is nice, right?).
Though that's not practical: we need a full drop-in replacement without
touching the existing init.d scripts, and we don't even want to touch
the LSB headers at all (that should be left as a decision).
But the good news is that there is already a perl script to transform
the LSB headers into an OpenRC header. There is even 2 versions: one in
perl, and one in Python. It is well possible that it will be
reimplemented in C, to avoid any kind of dependencies.
One of the problem also is that OpenRC doesn't understand the concept of
X-Start-Before: (it only has the concept of Required-Start /
Required-Stop). So something will have to be done so that we have
support for that.
So the work to be done will be:
- Hook into update-rc.d, somehow either understand or convert the LSB
headers of existing script, or convert them on-the-fly (maybe in another
directory, like /etc/init.d/openrc or something similar).
- Add code so that it can support X-Start-Before
- Add a bit of configuration so that it can build on kFreeBSD
- A tinny bit of adaptation so that the OpenRC ebegin / eend calls are
replaced by the usual lsb-base calls (I didn't look at it much, but that
shouldn't be hard, really), so that we get the nicer usual Debian boot
script prints.
I just tried to build it in kFreeBSD (on a virtualbox VM), and
unfortunately, it suffers from the usual problems in this arch: it needs
a bit of adaptation, because it doesn't detect the arch correctly. It
should really be only configuring and not programming (eg, write the
mk/kFreeBSD.mk files, etc.), and not code, since there are already some
build for OpenRC working in many *BSD unix (FreeBSD, NetBSD...).
I'm not really sure if there's more work to be done, but I think that
should be it. Probably heroxbd or Roger (hereby CC:) can tell their
opinion on what's left to implement. If that is it, then that's not so
much, IMO, and that's not so hard either (the hardest part, IMO, is the
X-Start-Before support, which is the only part which requires a bit of
thinking and algorithm, though since we already have implementation in
sysvrc, it should be fairly easy to have a look how it is done...).
We currently have a Google Summer of Code project to cover the above,
for which I am a mentor. Roger Leigh & heroxbd (who is a Gentoo
developer, and upstream for OpenRC) are co-mentors. I have good hopes
that by September we will have all of the above implemented (this
depends how good the GSoC student will be, and it is my understanding
that I can't, for the moment, disclose (yet) who we have chosen among
the 6 candidates).
For those who want to see an example of what a runscript looks like,
here's 2 examples, taken from the source of OpenRC on our Alioth Git (in
collab maint):
~/sources/debian_packaging/openrc/openrc# more init.d/swap-blk.in
#!@PREFIX@/sbin/runscript
# Copyright (c) 2007-2008 Roy Marples <roy@marples.name>
# Released under the 2-clause BSD license.
depend()
{
before fsck
keyword -jail -prefix
}
start()
{
ebegin "Activating block swap devices"
swapctl -A -t blk >/dev/null
eend 0 # If swapon has nothing todo it errors, so always return 0
}
stop()
{
ebegin "Deactivating block swap devices"
swapctl -U -t blk >/dev/null
eend 0
}
~/sources/debian_packaging/openrc/openrc# more init.d/rarpd.in
#!@PREFIX@/sbin/runscript
# Copyright (c) 2007-2008 Roy Marples <roy@marples.name>
# Released under the 2-clause BSD license.
command=/usr/sbin/rarpd
command_args="-f $rarpd_args"
pidfile=/var/run/rarpd.pid
name="Reverse ARP Daemon"
required_files=/etc/ethers
if [ -z "$rarpd_interface" ]; then
command_args="$command_args -a"
else
command_args="$command_args $rarpd_interface"
fi
command_background=YES
depend()
{
need localmount
after bootmisc
need net
}
These are 2 random examples taken from the source, they might not be the
best. Feel free to have a look yourself (in the init.d folder of the
sources on the Git on Alioth: see below). There are also some much more
complex runscripts available, and some which are even smaller than the
above (not one liners, but nearly...).
I believe that the #!/sbin/runscript isn't even needed anymore, and that
using #!/sbin/sh also works (heroxbd, can you confirm that fact?).
As you can see from the above, there are multiple ways to implement a
runscript. Either you just use the current init.d sysvrc scripts, which
are supported. Either you re-implement the start() and stop() function.
Either you simply tell OpenRC what your command and daemon is, and
OpenRC does the rest. This is in fact, what I like about it. It leaves
the maintainer free to do what he feels right, and doesn't tight you in
a closed declarative only environment, even though that is what you
should stick to if possible (of course, why make things simple if you
can make it complicated? :) ).
Now, about help: *OF COURSE WE ACCEPT HELP*!!! Feel free to spend your
nights on it. I currently have no time to do the work myself (I have
really enough work to do on OpenStack). If you decide to help, I'm sure
you will find it a lot of fun. This project is really cool and simple,
and hacking on it is a real pleasure. When I spent an afternoon with
Patrick working on a proof of concept, it was just great!
If you wish to download the package source, it's there:
git://anonscm.debian.org/collab-maint/openrc.git
it currently has the lsb.pl script as a patch over here:
debian/patches/lsb-header-support.patch
though it doesn't have the python implementation of Bill Wang.
Roger, Patrick, Bill, heroxbd, your comments on the above are more than
welcome. I hope I didn't write too much false statements... :)
Cheers,
Thomas Goirand (zigo)
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