Re: [netmod] system configuration sync mechanism

[Andy Bierman <[e-mail]>]

On Mon, Aug 2, 2021 at 3:31 PM Kent Watsen <[e-mail]> wrote:

>
> Hi Balazs, Andy, Quifang,
>
> I agree a new datastore will just add complexity without any value.
> Your solution approach is better, but I think it would require a new YANG
> version
> to allow config node XPath to reference non-config nodes.
>
>
> In no case is there a need for a config Xpath to ref non-config.
>
>
> Another solution is to model the referenced node as config=true, but setup
> automatic NACM rules so no user editing is allowed. This works well for
> setting up an initial config that gets saved and not changed unless a
> reset is done.
>
>
> I don’t like the NACM dependency.
>
>
> What if <intended> is what is NV-stored?  When that occurs, the config
> changes from system to user config.
> Routers have been saving the combined config for decades. IMO the standards
> intentionally avoid discussing the conversion of a datastore to/from
> NV-storage.
>
>
> I’m unsure about this point, but a don’t see any dependency on an NV-store
> needing to use a particular encoding or format.
>
> As I see it this is the same problem that we discussed in
>> https://github.com/netmod-wg/yang-next/issues/41.
>>
>> I know this is a radical change, but I think using a new YANG extension
>> to create a read-only config=true datatype is a much cleaner solution. One
>> which some companies have already implemented.
>>
> +1
>
> Actually, separate running and system would be a radical change, not this.
> Cleaner and less disruptive.
>
>
> I disagree with the need to resolve issue #41 here, and I disagree a
> <system> datastore would be a radical change, or even complicated.
>
> That said, something like RFC 6243 (with-defaults) but called
> “with-system” could work.  That is, the “system" config is like <running>
> config that is hidden until asked to be revealed. It would be interesting
> to discuss if “with-defaults" returns all of the system config, or just
> the parts that are used, assuming we define “used” appropriately.
>   Presumably system-defined ordered-list entries cannot be ordered by user,
> or used as before/after pivots.
>
> We could even do both: have a read-only <system> datastore *and* a
> "with-system" interaction API.  Each complimenting the other.
>


I prefer neither.
I think NMDA <get-data> with an origin-filter and/or with-origin parameter
already solves this problem.


Andy


> FWIW, a "with-system <running>” still may not pass validation if, e.g.,
> templates need to be expanded.  Of course, any controller/orchestrator can
> expand the templates themselves to resolve that concern.  Such a system
> could also fetch <system> without skipping a beat.
>
> Thought exercise: a controller is managing 1000 endpoints all running the
> same software version.  Is it better for the controller to get "with-system
> <running>” 1000 times, or get <system> once and have knowledge for how
> its merged in?
>
> K.
>
>
>
>
>