feature suggestion: initial generation of management network

[Dan Kenigsberg]

On Mon, May 20, 2013 at 03:18:52PM -0400, Alon Bar-Lev wrote:
> 
> 
> ----- Original Message -----
> > From: "Itamar Heim" <iheim at redhat.com>
> > To: "Alon Bar-Lev" <alonbl at redhat.com>
> > Cc: "Livnat Peer" <lpeer at redhat.com>, "arch" <arch at ovirt.org>, "Mike Burns" <mburns at redhat.com>
> > Sent: Monday, May 20, 2013 10:10:20 PM
> > Subject: Re: feature suggestion: initial generation of management network
> > 
> > On 05/20/2013 04:08 PM, Alon Bar-Lev wrote:
> > >
> > >
> > > ----- Original Message -----
> > >> From: "Livnat Peer" <lpeer at redhat.com>
> > >> To: "Alon Bar-Lev" <alonbl at redhat.com>
> > >> Cc: "Moti Asayag" <masayag at redhat.com>, "arch" <arch at ovirt.org>
> > >> Sent: Monday, May 20, 2013 3:55:42 PM
> > >> Subject: Re: feature suggestion: initial generation of management network
> > >>
> > >> On 05/20/2013 02:58 PM, Alon Bar-Lev wrote:
> > >>> Hi,
> > >>>
> > >>> Now another issue... ovirt-node.
> > >>>
> > >>> In ovirt-node, the node already defines a bridge which is called
> > >>> br at INTERFACE@, this is done automatically.
> > >>> The IP address of ovirt-node is assigned to that bridge, so we always
> > >>> have
> > >>> a bridge at ovirt-node.
> > >>>
> > >>> I have the following useless in my code, most is legacy... the
> > >>> question...
> > >>> Can this also be automated by the new code at engine side?
> > >>> It should or things will break...
> > >>>
> > >>
> > >> For ovirt node -
> > >>
> > >> For images 3.3 and above the code below can be removed, we will make
> > >> shore that the ovirt-node-plugin-vdsm would not create the brXXX bridges
> > >> (or if we have no choice remove them).
> > >
> > > I thought this is created in the node-core...
> > > Just confirmed.
> > > A node without vdsm plugin also create that bridge.
> > > vdsm has nothing to do with this process as far as I know.

Indeed. And for this reason, ovirt-node should avoid creating these
brXXX bridges when ovirt-node-plugin-vdsm is installed. Obviously, this
can be done only from 3.3 and forward.

> > >
> > >> For images 3.2 and below we still need this code, because oVirt node
> > >> creates brXXX bridges and the engine do not configure the network
> > >> automatically if a bridge exists on the interface.
> > >
> > > It is not just 'need this code' it is that we cannot use the bridgeless
> > > solution at enigne.
> > > Options:
> > >
> > > 1. We need to detect node version and perform bridgeless deployment if node
> > > is >= x, but we do not know this at engine when we deploy a host... we
> > > even do not know that it is ovirt-node.
> > >
> > > 2. I release a new minor version of ovirt-host-deploy that delete the
> > > bridge regardless of the mode.
> > >
> > > 3. Engine will be able to delete this bridge just like he is able to create
> > > the management bridge.
> > >
> > >> The down side to the above is that for management networks that
> > >> configured in the engine as bridgeless the management network on the
> > >> host would still be bridged thus will be marked as not-in-sync.
> > >
> > > Right, and because of that I think that (3) is the best solution.
> > 
> > adding mike - not sure if this is the solution we prefer, but if we
> > don't want the bridge, it should not be there and be part of the
> > responsibility of the plugins that do want it.
> > 
> > at some point we will move to 4.0, deprecating support for things older
> > than say 3.4. so that's another way to cleanup old code if we need it
> > for backward compatibility in the meantime, flagging it for removal in 4.0.
> 
> I do not understand why it is easy to add a bridge but not remote a bridge if it is exists.
> 
> This regardless of the requirement to remove/leave the bridge in ovirt-node.
> 
> If the feature exists in both engine and vdsm, and engine can
> enumerate bridges why not simply use these feature in order to
> provision the existing ovirt-node correctly?

The bootstrap-time setupNetwork has to be automatic, of course.
It should create the management network, but should not ruin
pre-existing networks, that might have been defined by an admin on the
host. But we cannot distinguish an ovirt-node automatic brXXX bridge
from a same-named network, intentionally defined there.

I'm not sure if anyone is using or expecting these breth* bridges.
In the vdsm/engine context, they are no more than nuisance. Someone once
told me that such nuisance should be removed at the nearest point
possible, and luckily, we already have the code to do this in
ovirt-host-deploy.

So I'm voting for (3): if ovirt-host-deploy does not receive
VDSM/managementBridgeName, it should still remove the brXXX bridges.

Dan.