Yang model integrity constraints/enforement for leafref

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Yang model integrity constraints/enforement for leafref

[olofhagsand]

From a yang perspective, if you have an object A and a leafref to A, then if you remove A, the validation will fail. E.g from test/test_leafref.sh ("template" means leafref"):

   olof@vandal> set sender A              
   olof@vandal> set sender B template A
   olof@vandal> validate 
   olof@vandal> delete sender A
   olof@vandal> validate 
   Nov 23 11:38:37: Validate failed. Edit and try again or discard changes: application operation-failed   Leafref validation failed, no such leaf: A 

CLI supports leafref when doing completion but does not enforce them, you can enter other leafrefs than "A" (ie "C"), but you will fail on validate/commit. Therefore, the CLI support of leafrefs is "soft", it assist but does not enforce. If you wish to have an invalid configuration in the candidate config you can.
However, once you validate/commit, an invalid reference should not be allowed (including you case with "dangling" references). If you see such a case it is an error.

It would in principle be possible to strictly enforce syntactic constraints in candidate, but it would result in a very strict command-line tool. Sometime you may want to add/remove objects so that they are not valid during an intermediate period, such as copy/paste large number of lines. With strict enforcement, every incremental change would have to be valid, so that you may have to perform operations in a very strict order. One example is renaming an object (A->B), both if you rename the object first, as well as renaming the leafrefs would give you an intermediate invalid state.

[katdiam]

Thanks a lot for your response, hope you are having a wonderful thanksgiving holidays!

I tried routing-instance in [email protected], created a routing instance on interface eth0(type if:interface-ref), I am able to delete interface eth0, the validation did not fail. Did I miss something?

[email protected]:
744 container routing {
....
747 list routing-instance {
...
824 container interfaces {

827 list interface {
828 key "name";
829 description
830 "List of network layer interfaces assigned to the routing
831 instance.";
832 leaf name {
833 type if:interface-ref;
834 description
835 "A reference to the name of a configured network layer
836 interface.";
837 }
838 }
839 }

server03> set interfaces interface eth0 type ex:eth
server03> set routing routing-instance rt0 interfaces interface eth0
server03> delete interfaces interface eth0
server03> show configuration
routing {
routing-instance {
name rt0;
type rt:default-routing-instance;
enabled true;
interfaces {
interface {
name eth0;
}
}
}
}

[katdiam]

I did validate after "delete interfaces interface eth0", it did not fail.

server03> set interfaces interface eth0 type ex:eth
server03> set routing routing-instance rt0 interfaces interface eth0
server03> delete interfaces interface eth0
server03> validate
server03>

[katdiam]

For the routing-instance on eth0 example above, should the "delete interfaces interface eth0" failed (since routing instance interface is of type if:interface-ref)? But it did not fail.

[olofhagsand]

The validate should fail.
Not the delete interfaces interface eth0. Did it not?

[olofhagsand]

Resolved and obsolete question.