RFC: deprecating/obsoleting netcf package and libvirt virInterface*() APIs

[Michal Privoznik]

On 12/2/20 8:47 PM, Laine Stump wrote:

> So, that's my piece to speak. I'm looking for opinions and ideas on a 
> few different fronts:
> 
> 1) Does this generally sound like a good direction? Or is there 
> something I'm ignoring that renders my points moot?

Yes, it sounds good. A few years back I wanted to adapt netcf for my 
distro, but never gotten around it, since there was no real consumer, 
only my motivation to build libvirt with everything possible.

> 
> 2) If we are going to do it, how should we proceed?
> 
> We obviously can't simply *remove* the virInterface API from libvirt 
> (since that would destroy backward compatibility guarantees), but could 
> immediately begin logging some sort of "this API is deprecated" message 
> when any of the functions are called, and then in a later release change 
> the APIs to return an error (while simultaneously removing netcf from 
> the build and dependency lists). At the same time, we would need to 
> decide if the "interface status" functionality needs to be maintained 
> within appropriate virInterface*() APIs, reproduced in 
> virNodeDeviceGetXMLDesc(), or just dropped altogether.

What we usually do is we remove the driver implementation and let public 
API report unsupported error (since driver->XXX callback is going to be 
NULL), for instance: 464a41bc0de. Before that, we reported a deprecated 
error (6f532d7ffc3 and 5cc402a9b4c).

This was paired with documentation:
a8073797ce174f6eaa622104e4fd33ee88cb6fad

Michal