Re: [yang-doctors] YANG dialects?

[Andy Bierman <[e-mail]>]

On Wed, Dec 18, 2019 at 1:01 PM Martin Bjorklund <[e-mail]> wrote:

> Andy Bierman <[e-mail]> wrote:
> > Hi,
> >
> > I noticed in the help output for pyang 2.1:
> >
> >   --mef                 Validate the module(s) according to MEF rules.
> >   --ieee                Validate the module(s) according to IEEE rules.
> >   --ietf                Validate the module(s) according to IETF rules.
> >   --bbf                 Validate the module(s) according to BBF rules.
> >   --lint                Validate the module(s) according to RFC
> 8407rules.
> >
> >
> > I guess --openconfig is missing (since they have their own rules for YANG
> > as well)
> >
> > I hope these different rules are for style only, and not redefining YANG.
>
> Right, these are style rules.  Note the help text for "--lint" - it
> verifies the rules defined in RFC 8407.
>
> All the others invokes --lint, and in addtion validates module names
> and namespaces (e.g. --ietf checks that the module is called "ietf-*"
> ot "iana-*").
>
> > I suspect it is more than that.
>
> No, not for these validators.
>
>
OK



> > I am aware of at least 3 openconfig issues that do not follow YANG rules:
> >    - repurposing pattern-stmt to use a different syntax
> >    - referencing config=false nodes from config=true context node for
> > when-stmts
> >    - use of identity strings without prefixes in XPath, where the default
> > module does
> >      not contain the identity (it is in an imported module instead)
> >
> > Should we just continue hacking the tools in proprietary ways to deal
> with
> > the inconsistencies? Are there any issues the IETF (or YANG doctors)
> > could or should address?
>
> These module are published and are being used.  Vendors that want to
> use them will have to work around the problems.  There's nothing we
> (the IETF) can do about them.  However, it is trivial to fix all these
> issues so that the modules are valid YANG, but it doesn't seem this is
> high on OpenConfig's priority list.
>
>
>

Not so easy for all of them.
(1)
The pattern-stmt disaster cannot be addressed.

(2)
I see the config=false access issue in ietf-if-extensions@2019-11-04 and
ietf-if-l3-vlan@2019-11-04


      container dot1q-vlan {
        must
          'count(../../if-ext:forwarding-mode) = 0 or ' +
          'derived-from-or-self(../../if-ext:forwarding-mode,' +
                                '"if-ext:layer-3-forwarding")' {


forwarding-mode is config=false

I am trying to compile ietf-routing-policy and eventually ietf-bgp.
3 different compilers are giving 3 different answers for
ietf-routing-policy,
related to this dot1q-vlan container.

(3)
Users want to specify identities without the prefixes.
Should tools allow it or follow YANG rules?
>From XPath POV it is just a string literal.
I know they are supposed to use derived-from (or-self) but they don't
follow that rule either.


/martin
>
>
Andy


>
>
> >
> > For starters, can somebody explain the different rules pyang is checking
> > here?
> >
> >
> > Andy
>