Re: [RFC PATCH common] section config: correctly handle required options in write_config

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

On Thu, Mar 12, 2026 at 01:19:53PM +0100, Daniel Kral wrote:
> On Thu Mar 12, 2026 at 10:47 AM CET, Max R. Carrara wrote:
> > Just had a look at your patch—nice that you spotted this!
> >
> > I think this fix here should be fine, but I think it would be nice if
> > you added a test: Replicate the broken behavior first, and then fix it
> > together with this patch here. So, basically a little bit of TDD.
> >
> > I'm not a big fan of TDD myself, but I think in this specific case it
> > would be beneficial for us to have a test like that—it's also
> > documentation at the same time.
> >
> > Perhaps a nice spot for that would be in the SectionConfig tests
> > directory [1] as a separate script or something—see the other scripts
> > for how the tests in there work. (ofc you can holler at me too!)
> 
> Thanks for the quick feedback!
> 
> Yeah, but for something integral as the section config adding some test
> cases documenting the changes would be great, I'll do that for the v2!
> 
> >
> > Regarding JSONSchema: I think the definedness check itself is fine—an
> > empty array is still "something" rather than nothing, so ...
> >
> > We could instead implement some of the other validation keywords [2] for
> > arrays, like e.g. `minItems`. I think an array that's `required` and
> > also has `minItems` set to `1` would allow you to express what you
> > initially wanted where you fixed #7399 [0], right?
> >
> > I just hope that this is possible in your current JSONSchema—Wolfgang
> > and I have spoken about some things related to this a (longer) while
> > ago; I believe it was about empty strings / zeroes as well. *That* might
> > be a bit more complicated to solve, though and might even require a
> > JSONSchema v2 of some sorts, but I don't have all the details in my head
> > at the moment.
> 
> Thanks for the insights, I haven't looked too closely at the json schema
> draft yet!
> 
> You're right, even though it seems that the draft doesn't specify any
> behavior regarding our `optional` property, my proposed change in our

Our optional property is just an "inlined" version of *not* putting
something in the enclosing object's `required` array. (IIRC we discussed
the possibility of adding that and slowly moving over to using that as
it would also make the perl<->rust conversion/interop easier in the long
run.

> json schema code would break assumptions around our code base and with
> all the `min*` properties in mind it indeed would be inconsistent if
> those `min*` properties default to `0`. So let's discard that idea.
> 
> >
> > [1]: https://git.proxmox.com/?p=pve-common.git;a=tree;f=test/SectionConfig;h=0967fb1eebf84b4ecad696901572fa7550d49941;hb=refs/heads/master
> > [2]: https://json-schema.org/draft/2020-12/json-schema-validation#name-validation-keywords-for-arr