Re: daemontools respin?

On Wed, Jun 09, 2010 at 09:15:09PM +0200, Bernhard Graf wrote:
> Another one worth a look might be ninit:
> http://riemann.fmi.uni-sofia.bg/ninit/

Thanks, I'll take a look.

> > The plan is to handle this entirely within svscan, to eliminate services
> > having to poll other services.  Are you up yet?  Are you up yet?
>
> I'm not sure, if I get this. How can you tell (in a daemontools-like
> init setup) when a service is ready to do its job without actually
> asking it?  I mean, the fact that a program is running does not
> necessarily mean, that it is ready.

For the majority of services that would be dependencies, most of the
waiting part would be done in the start script (which runs just once),
and the service would not count as "up" until that exits.  For example,
many things would depend on the network being up, which is a one-time
action.  However, that doesn't necessarily help for jobs that would wait
on a service being available on a particular port or whatever.

> This is much easier with the synchronous SysV startup process, with
> self-daemonizing services: By terminating the main process such a daemon
> can indicate, that the daemonized subprocess is ready.

As much as I hate self-daemonizing services, this an advantage to them
(possibly the only advantage IMNSHO).  Other signalling mechanisms could
be devised, but they're not nearly so intrinsic.

-- 
Bruce Guenter <[email protected]>                http://untroubled.org/

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