On Fri, Oct 28, 2011 at 01:21:39AM +0200, Hans van Kranenburg wrote:
> An ovs-only solution could be to facilitate an init-script that
> calls ifup for all interfaces that are added by ovs during boot, and
> calls ifdown for them before shutting down ovs. Or even not a
> separate init-script, but this could be a (debian-only?) option in
> OVS saying: "should I call ifup and ifdown for you when
> adding/removing interfaces?" This way (by using ifupdown) the ip
> addresses and other fancy things can be defined in
> /etc/network/interfaces as usual. OVS knows which interfaces it adds
> to the system during boot, so it could be zero-configuration.
This is interesting. As a generalization, one could add a set of
scripts that ovs-vswitchd invokes before and after it creates an
interface and before and after it removes one.
Some issues that come to mind:
* We generally don't allow the database to specify full names
of commands to run, files to create, etc., because
ovs-vswitchd runs as root and we don't want database users
to necessarily have root privilege. So we'd probably just
to have to choose some "standard" script names and pass the
interface name as an argument.
* So far, we've been talking about ovs-vswitchd startup, but
OVS can create and destroy network devices (and other kinds
of vports) at other times, too. I guess that we'd want
these scripts to run whenever OVS does this, not just at
startup, but we'd have to think about that.
* I'm not quite sure what should happen on OVS restart
(if someone kills and restarts the daemon). I guess it
should only run the script if it has to actually create the
device. There'd be a race, though: if ovs-vswitchd creates
the device and then someone kills it before it runs the
script, then on restart it wouldn't run the script.
Probably we can ignore this race, but I thought I'd mention
it anyway. Alternatively we could *always* run all the
scripts on startup, in which case the scripts would have to
be designed to be idempotent.
* If we want these scripts to run at shutdown, I guess we'd
have to actually delete the interfaces.
Any further thoughts?
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