dovecot - Oct 2010 - add basic systemd support to dovecot

Hi all,

In the last days, I've been trying to add support for systemd[1]
socket activation to dovecot. The basic idea is that systemd takes
care of opening the sockets needed by dovecot to communicate with
external processes, and when a connection happens on one of these
sockets, systemd spawns dovecot, and then dovecot uses these sockets
instead of creating its own sockets. The main reason why I hacked on
this was that I wanted to get on-demand startup of dovecot on my home
box.

WIth the patch attached to this email, I'm now able to do that. The
patch includes a dovecot.socket file which should be seen as a sample
file, however I'm not sure what is the best way to handle this file
(systemd uses it to know which sockets dovecot needs).

What I wanted to ask the list for now is if such a patch is wanted,
and to get feedback on how things are done in it, and what should be
improved in it. [2] and [3] might be useful reading while looking at
the patch.

Thanks in advance for the feedback!

Christophe

[1] http://www.freedesktop.org/wiki/Software/systemd
[2] http://0pointer.de/public/systemd-man/daemon.html
[3] http://0pointer.de/public/systemd-man/sd-daemon.html
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On Wed, 2010-10-20 at 22:54 +0200, Christophe Fergeau wrote:
> What I wanted to ask the list for now is if such a patch is wanted,
> and to get feedback on how things are done in it, and what should be
> improved in it. [2] and [3] might be useful reading while looking at
> the patch. 
You can simplify the environment preserving with these changes:

http://hg.dovecot.org/dovecot-2.0/rev/e0a97842182f
http://hg.dovecot.org/dovecot-2.0/rev/d1fd5b84d410
> +if HAVE_SYSTEMD
> +dovecot_SOURCES += sd-daemon.c
> +noinst_HEADERS += sd-daemon.h
> +endif
I don't think this is portable. You could do it instead like:

if HAVE_SYSTEMD
SD_SOURCES = sd-daemon.c
endif

dovecot_SOURCES = \
	$(SD_SOURCES) \
	..

noinst_HEADERS = \
	sd-daemon.h \
	..

I don't think there's any reason to put sd-daemon.h behind
"if".
> +        AS_HELP_STRING([--with-systemdsystemunitdir=DIR], [Directory for
systemd service files]),
> +        [], [with_systemdsystemunitdir=$($PKG_CONFIG
--variable=systemdsystemunitdir systemd)])
Is this a common name for this option? If not, I'd prefer a shorter
name.