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Re: starting service order
Re: starting service order
Tue, 06 Jul 2004 16:59:53 +0200
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Jan-Henrik Haukeland wrote:
Yes that's right, i think we can use the gentoo doc and meaning of these
keyword as a basis, as i said in another mail, gentoo has a really
finegrained services order and dependency system (it's explain in the
docs here: http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?
part=2&chap=5#doc_chap4) but it missed the great features of monit and
could benefit a lot of it.
2) a kind of ordering, or at least, the ability to not startup the
subsequent service in the list if the previous did not already
to startup _without_ using a dependency
it could be implemented by keywords like before/after
Gentoo linux already provide this functionnality (look here:
you can define order with before after
dependencies need/use and also provide
for example you can say that qmail "provide mta" and "need net"
and that nagios "need mta"
so the system knows that he must start qmail before nagios (if you
had use the "use" keyword instead of "need" it means that qmail can
fail it's okà
"provide" is also because you can say that many service provide the
same functionnality, eg: mta -> qmail, postfix, exim
(1) Interesting idea. It sounds like something that monit could
benefit from. It means that we need to replace dependency in monit
with the keyword "need" and add the keyword "use" for start order and
as a weak dependency. (If I got this right?)
3) some tool to easily rearrange the services (a chkconfig-like
I wrote this tool, it was easy, i just modified the default tool
from gentoo (it was just a matter of 5 lines)
the ability tu support different runlevels
Care to share the tool with the list?
of course i can share it, i didn't do i yet because it's really gentoo
specific (i modified the default tool)
If you want i could wrote a lite version of it just for monit.
It's just a matter of managing symlinks and tell monit to reread it's
config file (plus some sanity checks).
and i don't see why monit couldn't do this?
for example djb's daemontools where built to manage services (they
manage qmail/djbdns) and monit seems to be a daemontools++. too bad
he also missed the ability to define services start order...
I think that monit can remplace the default system, because the onlyt
things that the default init system has to do, is stating/stopping
system in the right order nothing more
If we missed this it doesn't mean that it cannot be changed. I also
think that you can use monit with success as a replacement for
sysinit startup scripts, but means to set the start order is needed,
(2) In addition monit should have the ability to start a process
without depending on a pid file. (As stated in the first comment to
monit here, http://freshmeat.net/projects/monit/) I.e. monit needs to
listen to the SIGCHLD signal for processes it start, so if a child
dies monit get a signal and can restart the process. I haven't looked
at the init nor the daemontools code, but I'm pretty sure this is
what those programs do. The reason we don't do this already is that
monit was (initially) designed to monitor processes that was started
outside of monit's control. (To listen for SIGCHLD monit must start
that's maybe why in system using daemontools (runit for example) all
services are child or the monitoring process (svscan/supervise), and the
service MUSTN'T fork to be monitored by daeamontools
I think as a start we should add (1) and (2) to our TODO list. What
do the other commiters think?
Marco suggested in his email some threading to not "block" monit process
while it is starting another process, and also to be able to "see" if a
process is in "starting in progress" state.
Re: starting service order, Marco Ermini, 2004/07/06
- starting service order, Sebastien ESTIENNE, 2004/07/05
- Re: starting service order, Marco Ermini, 2004/07/05
- Re: starting service order, Sebastien ESTIENNE, 2004/07/05
- Re: starting service order, Jan-Henrik Haukeland, 2004/07/06
- Re: starting service order,
Sebastien ESTIENNE <=
- Re: starting service order, Martin Pala, 2004/07/06
- Re: starting service order, rory toma, 2004/07/06
- Re: starting service order, Christian Hopp, 2004/07/07
- Re: starting service order, Jan-Henrik Haukeland, 2004/07/07