Re: [Libguestfs] [PATCH] v2v: remove MAC address related information

Richard W.M. Jones
2018-02-27T12:34:09Z

On Tue, Feb 27, 2018 at 12:53:08PM +0100, Pino Toscano
wrote:
> On Tuesday, 27 February 2018 12:35:36 CET Tomáš Golembiovský wrote:
> > Remove ties to MAC address because it is likely to change.
>
> v2v tries to preserve the MAC address of network interfaces; few months
> ago we did a fix regarding this:
> https://bugzilla.redhat.com/show_bug.cgi?id=1506572
>
> The approach of this patch is IMHO not good, since it removes the MAC
> address from the network-scripts, but still the rest of v2v will try
> to preserve the MAC addresses.

We preserve the MAC address in metadata.  On the other hand AIUI this
patch only removes the association in the ifcfg files and the guest
will reassociate it when it boots (albeit it might then mix up the
ethernet interfaces so that's not good).

There's IMHO a bigger problem which is not being addressed:

https://bugzilla.redhat.com/show_bug.cgi?id=1318922

> What's the reason behind this patch?

There's a bit of background which is missing.  Tomáš and I had some
discussions (privately, unfortunately) with the ManageIQ developers
who are integrating virt-v2v into MIQ/CloudForms.  Their existing
software runs a separate virt-sysprep step on guests after they have
been converted by virt-v2v.  They disable all sysprep the operations
except for just a couple, including ‘net-hwaddr’, so the effect is
roughly the same as this patch.

The question was raised why they need to do that as a separate step
and why virt-v2v doesn't do it.  And indeed there was some discussion
about whether or not converted guests need a new MAC address -- it's
at best unclear -- it is thought that VMware might reuse MAC addresses
which have "left" the hypervisor, although no one knows if that's
really true or not.

I don't have much opinion on this.  Maybe it's best for CFME to
continue to run virt-sysprep as a separate step.

Rich.

--
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