Re: [netmod] YANG augmentation in notification

[Martin Björklund <[e-mail]>]

Hi,

Alex Huang Feng <[e-mail]> wrote:
> Dear NETMOD WG,
> 
> Some time ago I sent this email to the YANG doctors to check with
> them. I would also like to have your insights on mandatory augmented
> leaves.
> 
> We are working on a YANG module for the following draft:
> https://datatracker.ietf.org/doc/draft-tgraf-netconf-yang-notifications-versioning/
> <https://datatracker.ietf.org/doc/draft-tgraf-netconf-yang-notifications-versioning/>
> In this draft, we are augmenting a notification container in the YANG
> module adding new leaves.
> We would like to have some of these leaves mandatories if the current
> YANG is used but are having an error code using the pyang compiler
> (error: cannot augment with mandatory node "revision-label”).
> 
> The resulting YANG tree without the mandatory statement is the
> following:
> module: ietf-yang-push-metadata
> 
>   augment /yp:push-update:
>     +--ro module?                     string
>     +--ro namespace?                  string
>     +--ro revision?                   rev:revision-date-or-label
>     +--ro revision-label?             ysver:version
>     +--ro datastore-xpath-filter?     yang:xpath1.0 {sn:xpath}?
>     +--ro datastore-subtree-filter?    {sn:subtree}?
> In RFC7950 Section 7.17, there is the following statement regarding
> the mandatory fields in augmented YANGs:
> 
> If the augmentation adds mandatory nodes (see Section 3
> <https://www.rfc-editor.org/rfc/rfc7950#section-3>) that
>    represent configuration to a target node in another module, the
     ^^^^^^^^^^^^^^^^^^^^^^^

>    augmentation MUST be made conditional with a "when" statement.  Care
>    must be taken when defining the "when" expression so that clients
>    that do not know about the augmenting module do not break.
> 
> Does this statement applies to YANG notification containers?
> Or does this statement applies only to configuration YANG modules?

It applies to configuration nodes.

> Is this a pyang compiler bug?

Yes.


/martin



> 
> Regards,
> 
> Alex Huang Feng