Re: [netmod] Does the YANG "status" statement inherit from its parent node?

[Andy Bierman <[e-mail]>]

On Wed, Dec 21, 2016 at 2:54 AM, Martin Bjorklund <[e-mail]> wrote:

> Andy Bierman <[e-mail]> wrote:
> > On Wed, Dec 21, 2016 at 1:32 AM, Martin Bjorklund <[e-mail]>
> wrote:
> >
> > > Ladislav Lhotka <[e-mail]> wrote:
> > > > Martin Bjorklund <[e-mail]> writes:
> > > >
> > > > > Robert Wilton <[e-mail]> wrote:
> > > > >> Hi,
> > > > >>
> > > > >> The definition of "status" in RFC 7950 in section 7.21.2 (full
> text
> > > > >> below), states:
> > > > >>
> > > > >> If no status is specified, the default is "current".
> > > > >>
> > > > >> From my interpretation of the text in the draft, this implies
> that the
> > > > >> status of the "new" child leaf in the following example is
> "current",
> > > > >> and that this example is allowed!
> > > > >>
> > > > >> My questions are:
> > > > >>  - Is my interpretation of the current text correct?
> > > > >
> > > > > Yes.
> > > > >
> > > > >>  - Is this actually the best behaviour, or should it inherit like
> the
> > > > >>    config statement?
> > > > >
> > > > > I think the idea was that if the status != current, it is better
> for
> > > > > the reader if it is explicitly stated.
> > > > >
> > > > >>  Should I raise an errata for this?
> > > > >
> > > > > No.
> > > > >
> > > > > However, we could have said that a current node under a deprecated
> > > > > node (etc) in the same module is an error, in order to force people
> > > > > (through the useage of YANG validators) to detect and fix this.
> > > >
> > > > Since "current" is the default, correctly deprecating a subtree would
> > > > mean to explicitly add the "status" statement to every single node in
> > > > the subtree.
> > >
> > > Yes.
> > >
> >
> > Please explain what it means for YANG to say
> > "The parent node is deprecated and going away but the child nodes are
> not.
> > They are current and are staying around."  This does not seem to make any
> > sense.
>
> Agreed.  But this should be invalid also if the status statements are
> given explicitly:
>

IMO the default should be inherit from parent, like the config-stmt.
It clutters the YANG module to add a status-stmt to every descendant node.
The status also applies to augment.  If /foo is deprecated than any
external augments
that adds nodes under /foo is also deprecated.  (Most obvious when you
change deprecated
to obsolete).



>
>   container a {
>     status deprecated;
>     container b {
>       status current;
>     }
>   }
>
>

I tested pyang with explicit statements and no warnings are given:


  container A {
    status deprecated;
    leaf AA {
      type string;
      status current;
    }
  }

  container B {
    status obsolete;
    leaf BB {
      type string;
      status current;
    }
  }


> Clearly an obsolete node removes all access of its descendant nodes.
> > There is no way to access /foo/child if /foo has been removed from the
> > server.
>
> Yes.
>
> > So how do I access a deprecated /foo/child node inside an obsolete /foo
> > container?
>
> You can't.
>

So the status-stmt clearly applies to descendant-or-self.



>
>
> /martin
>


Andy