[PATCH] spec: keep existing nwfilters uuid on update

[Laine Stump]

On 12/3/20 12:31 PM, Andrea Bolognani wrote:
> On Thu, 2020-12-03 at 17:39 +0100, Michal Privoznik wrote:
>> On 10/26/20 10:21 AM, Nikolay Shirokovskiy wrote:
>>> -cp %{_datadir}/libvirt/nwfilter/*.xml %{_sysconfdir}/libvirt/nwfilter/
>>> +# keep existing filters uuid on update
>>> +for dfile in %{_datadir}/libvirt/nwfilter/*.xml; do
>>> +    sfile=%{_sysconfdir}/libvirt/nwfilter/`basename $dfile`
>>> +    if [ -f "$sfile" ]; then
>>> +      uuidstr=`sed -n '/<uuid>.*<\/uuid>/p' "$sfile"`
>>> +      if [ ! -z "$uuidstr" ]; then
>>> +        sed -e "s,<filter .*>,&\n$uuidstr," "$dfile" > "$sfile"
>>> +        continue
>>> +      fi
>>> +    fi
>>> +    cp "$dfile" "$sfile"
>>> +done
>> I wonder if we should treat these .xml files as config files. I mean,
>> they can be changed by user and if they have been we should not touch
>> them at update no matter what. But if they haven't, then we should
>> replace them because they may contain new, better rules.
>>
>> I've read spec file documentation here and it looks like
>> %config(noreplace) is doing just that:
>>
>> https://rpm-packaging-guide.github.io/#more-on-macros
>>
>> Would that solve the issue?
> I think treating them as configuration files is exactly the opposite
> of what we want to do, because they contain generated data (the
> UUID) and so they will *always* be different from what was included
> in the package.
>
> I believe the only sane way to deal with them is mirror what we do
> for the default network, and just leave the files in /etc alone if
> they already exist: the user might miss out on improvements, but
> that's still preferable to potentially wipe out local changes.
>

Also, we need to avoid adding things to the %post script for rpms (as we 
recently discussed when Andrea posted patches _removing_ similar code 
for the default network from libvirt.spec.in) - Fedora SilverBlue filed 
a bugzilla report about that awhile back. Instead, we should check if a 
uuid was added during the parsing of the nwfilter at libvirtd startup 
time, and rewrite the config if so.


Here is a pointer to Andrea's patches:


  https://www.redhat.com/archives/libvir-list/2020-November/msg01101.html


And here's a message from the discussion of V1 of those patches, where 
Andrea points out some of the inconsistencies in our handling of 
auto-generated uuids for various config objects:


  https://www.redhat.com/archives/libvir-list/2020-November/msg00970.html