Re: [PATCH v7 2/8] cxenstored: add support for systemd active sockets

[Ian Campbell <ian.campbell@citrix.com>]

On Wed, 2015-08-05 at 11:06 +0100, George Dunlap wrote:
> On Fri, Jul 18, 2014 at 12:28 AM, Luis R. Rodriguez
> <mcgrof@do-not-panic.com> wrote:
> > From: "Luis R. Rodriguez" <mcgrof@suse.com>
> > 
> > This adds systemd socket activation support for the C xenstored.
> > Active sockets enable xenstored to be loaded only if required by a 
> > system
> > onto which Xen is installed on. Socket activation is handled by
> > systemd, once a port for a service which claims a socket is used
> > systemd will start the required services for it, on demand. For more
> > details on socket activation refer to Lennart's socket-activation
> > post regarding this [0].
> > 
> > Right now this code adds a no-op for this functionality, leaving the
> > enablement to be done later once systemd is properly hooked into
> > the build system. The socket activation is ordered in aligment with
> > the socket activation order passed on to systemd.
> > 
> > [0] http://0pointer.de/blog/projects/socket-activation2.html
> 
> So with this patch in place, xenstored will not start on a system that
> has systemd, *even if it wasn't started from systemd*.

But where systemd is /sbin/init, right?

The case where xenstored was compiled with systemd support but systemd is
not /sbin/init should still be expected to work, and isn't what I think you
are complaining about here.

> Lots of systems (e.g., CentOS 7) have legacy systems in place to allow
> you to do things like "chkconfig --add xencommons" even on a systemd
> system.  I think we still want to work with those, right?

Isn't chkconfig --add still arranging for the thing to be started by
systemd under the hood? If not systemd on a host where /sbin/init==systemd
then what does else would start it?

If you are asking "should the sysvinit initscripts still be us(ed|able)
even though systemd is being used as /sbin/init on the host and a unit file
is present" then AIUI the systemd answer is "no". (We may choose to
disagree with systemd on this I suppose)

On the other hand, does this mean I can no longer start xenstored by hand
from the CLI? _That_ would seem to be worth preserving, for debugging etc
if nothing else.

Ian.