[libvirt] [RFC 0/7] Warn at runtime when deprecated features are used

[Andrea Bolognani]

On Fri, 2018-10-05 at 12:05 +0100, Daniel P. Berrangé wrote:
> On Fri, Oct 05, 2018 at 11:38:14AM +0200, Andrea Bolognani wrote:
> > Warnings printed on stderr -> users and developers will actually
> > see them, be annoyed by them, eventually cave in and act upon them.
> > 
> > Warnings written to a log -> nobody will notice them, until one day
> > things suddenly stop working apparently out of the blue.
> > 
> > We might pretend that's not the case, but really, it is.
> 
> Unless you're talking about a CLI tool (virt-install, virsh), there
> is no difference between those two scenarios. For virt-manager,
> virt-viewer, oVirt, OpenStack, KubeVirt, stderr is never going to
> be seen, it just ends up in a log file. So I don't find that
> distinction to be compelling.

Sure, I used "stderr" as a shorthand for "whatever reporting method
can be appropriately used by the application to shove a warning to
the user's face" :)

For a GUI application, it might be a dialog popping up or a message
showing scrolling throuhg the status bar or what have you; for
something headless, it might be an email delivered to the admin's
inbox.

The point is that the user should *not* be required to dig through
logs to find out they've been using deprecated features: they should
be *told* that's the case right when they do.

-- 
Andrea Bolognani / Red Hat / Virtualization