Re: [Rtg-yang-coord] apply to subset of all configuration in YANG model

Hi Tarek,

I think #2 is an easy and elegant solution for this particular
case. Templates are needed in cases where the data hierarchy is not
aligned with the needs for parameter inheritance - see the parallel
thread in this list about templates for routing instances and
routing protocol instances.

Lada

"Tarek Saad (tsaad)" <tsaad@cisco.com> writes:

> Hi YANG experts,
>
> There are cases where the same configuration data is to be applied on all (or some) nodes of a list and we’re seeking for advice. for example, if we have a list of interfaces (under a routing protocol "routing-proto" and I am trying to enable property foo on all such interfaces. We thought this could be done in several ways, and seeking thoughts and/or if consensus has been reach on it..
> 1) The trivial way is to configure foo repeatedly under all interfaces:
> routing-proto
>   interface A
>      foo 20
>   interface B
>      foo 30
>   interface C
>      foo 20
>
> 2) If apply “all” is sought, hierarchy can be used so to allow overriding defaults on all interfaces:
> routing-proto
>   foo 20
>   interface A
>   interface B
>      foo 30
>   interface C
>
> 3) Alternatively,  an apply-group (or template) or a reference to a set of configs can be used. In the referenced configuration set (apply-group or template), attribute foo is configured once and it applies to all interfaces referencing it. The apply-group ALL association with interfaces association can be *implicit* (not needing to configure it under every interface), but when configured for non-ALL case, it is flexible such that different apply-groups NAMES can be associated with different interfaces.
> apply-group ALL
>     interface ‘*’
>        foo
>
> routing-proto
> interface A
>   apply-group ALL
> interface B
>   apply-group ALL
> ….
>
> We can see this can be translated to YANG as:
> For this, an approach can be
> container ALL {
>        list interface {
>             key "interface";
>             leaf interface {
>                  type if:interface-ref;
>             }
>             leaf foo { type uint32; }
>             leaf apply-group { type leafref "/apply-group/name" }
> }
>
> Is there any recommendation or preference on adopting 2) or 3) or both?
>
> Regards,
> Tarek
>
>
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-- 
Ladislav Lhotka, CZ.NIC Labs
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