Yang modelling error - pyang

[Andre Castro]

Dear friends,

I'm a beginner on NSO services modelling and running into an issue while trying to run pyang against a yang file - described in one of the NSO lab guides.

NSO version is 5.1

Pyang 1.5, but also tried 1.7.8 and 2.1. Got the same errors though.

module vlan {
  namespace "http://com/example/vlan";
  prefix vlan;

  import ietf-inet-types {
    prefix inet;
  }
  import tailf-ncs {
    prefix ncs;
  }
  import tailf-common{
	prefix tailf;
  }
  description
	"Description...";
	
	revision 2019-11-05 {
		description
		"Initial revision";
	}
	augment /ncs:services{
		  list vlan {
			tailf:info "VLAN Service";
			key name;
			unique vlan-id;

			uses ncs:service-data;
			ncs:servicepoint "vlan";

			leaf name {
			  tailf:info "Service Instance Name";
			  type string;
			}
			leaf vlan-id{
				tailf:info "Unique VLAN ID";
				type uint32{
					range "1..4096";
				}
			}
			list device{
				tailf:info "L3 switch";
				key name;
				leaf name{
					tailf:info "Device name";
					type leafref{
						path "/ncs:devices/ncs:device/ncs:name";
					}
				}
			}
			list interface{
				tailf:info "Ethernet interface";
				key "intf-type intf-id";
				leaf intf-type{
					tailf:info "Ethernet interface type";
					type enumeration{
						enum Ethernet;
						enum FastEthernet;
						enum GigabitEthernet;
					}
				}
				leaf intf-id{
					tailf:info "Ethernet interface ID";
					type string;
				}
			}
		}
	}
}

Errors:

user@mypc:~/ncs-run/packages$ pyang vlan/src/yang/vlan.yang
vlan/src/yang/vlan.yang:5: warning: imported module ietf-inet-types not used
/home/user/nso/src/ncs/yang/ietf-yang-schema-mount.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/ietf-yang-schema-mount.yang:9: error: unexpected keyword "reference"
/home/user/nso/src/ncs/yang/ietf-yang-schema-mount.yang:15: error: unexpected keyword "reference"
/home/user/nso/src/ncs/yang/tailf-ncs-cluster.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-common.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-compliance.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-customers.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-devices.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-devices.yang:3707: error: XPath function "derived-from-or-self" is not defined in the XPath context
/home/user/nso/src/ncs/yang/tailf-ncs-devices.yang:3907: error: XPath function "derived-from-or-self" is not defined in the XPath context
/home/user/nso/src/ncs/yang/tailf-ncs-java-vm.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-log.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-packages.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-plan.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-python-vm.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-service-progress-monitoring.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-services.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-smart-license.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-snmp-notification-receiver.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-software.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs-ssh.yang:2: error: bad value "1.1" (should be version)
/home/user/nso/src/ncs/yang/tailf-ncs.yang:2: error: bad value "1.1" (should be version)

Any insights will be much appreciated.

Thank you

Andre

[gmuloche]

Hello,

in theory starting release 1.7 pyang should support YANG 1.1 and so this should not be an issue (essentially this error comes from being check against the re_version regex: https://github.com/mbj4668/pyang/blob/b7264db134929809c9749aed700f187ee4973482/pyang/syntax.py#L112

However what could be happening is the following: when you source ncsrc then it inserts pyang version 1.5 in your path (look at `which pyang`) and it won't necessary use the version you have installed on your system but the version that is shipped with NSO.

user@/tmp$ which pyang
/usr/local/bin/pyang
user@/tmp$ pyang --version
user@/tmp$ source /var/nso-5.2.1/ncsrc
user@/tmp$ which pyang
/var/nso-5.2.1/bin/pyang
user@/tmp$ pyang --version
pyang 1.5

In theory the error reported for yang 1.1 models should not be there in pyang >= 1.7 - regarding why pyang is not changed in newer NSO version have a look at this: https://www.tail-f.com/alternatives-to-pyang-tool/

[Andre Castro]

Eventually gave up from version 5.1.. Tried to work back with version 4.7 and worked as expected..

[jaheo]

Please try under commands on NSO 5.1 version

yanger [yangfilename].yang

NSO uses yanger to validate yang file for latest nso versions.

pyang is deprecated.