The yanglint tool is very useful for validation of Yang data models, validation of NETCONF data and NETCONF filter.
The following sections show some use-cases that can be done using yanglint. The aim of these examples is to show various detail error messages that can libyang provide because of Yang model knowledge.
It is possible to go through examples one by one. The clear command resets an internal context of libyang.
Let's have two data models ietf-netconf-acm.yin and ietf-netconf-acm2.yin. They differ in the module name but their namespaces are the same.
Preparation:
clear add ietf-netconf-acm.yin list
Output:
List of the loaded models (mod-set-id 5):
ietf-inet-types@2013-07-15
ietf-yang-types@2013-07-15
ietf-yang-library@2015-07-03
ietf-netconf-acm@2012-02-22
Command and its output:
> add ietf-netconf-acm2.yin
libyang[0]: Two different modules ("ietf-netconf-acm" and "ietf-netconf-acm2") have the same namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-acm"
ietf-netconf-acm-when.yin contains a syntax error. There is a bad syntax of when statement in YIN file.
<when value="../denied-operations > 0"/>
instead of
<when condition="../denied-operations > 0"/>
yanglint can not only discover this error but also advice a solution.
Preparation:
clear
Command and its output:
> add ietf-netconf-acm-when.yin libyang[0]: Parser fails around the line 258. libyang[0]: Missing argument "condition" to keyword "when".
Preparation:
clear add ietf-netconf-acm.yin
Unknown data
By default, yanglint ignores unknown data and no error is printed (you can compare real content of the datastore.xml file and what yanglint prints in the following command if you add -f xml option).
Command and its output:
> data datastore.xml
To handle unknown data as error, use strict mode (-s option).
Command and its output:
> data -s datastore.xml libyang[0]: Parser fails around the line 22. libyang[0]: Unknown element "interfaces". Failed to parse data.
Multiple top-level elements in a single document
As a feature and in conflict with the XML definition, yanglint (and libyang) is able to read XML files with multiple top-level elements. Such documents are not well-formed according to the XML spec, but it fits to how the YANG interconnects data trees (defined as top-level elements of a single schema or by multiple schemas).
Preparation:
Command and its output:
> clear > add ietf-netconf-acm.yin > add ietf-interfaces.yin > add ietf-ip.yin > add iana-if-type.yin
Command and its ouput:
> data -s datastore.xml
Different data content types
Since NETCONF requires the data described by YANG to be used in different situations (e.g. as , result of the with status data included or as a result of the without the status data and possibly filtered, so without specified subtrees), it must be possible to specify which kind of data is going to be parsed. In yanglint, this is done via -x option. The list of supported modes can be displayed by the -h option given to the data command. In general, the auto value lets the yanglint to recognize the data type automatically by the additional top-level elements added to the parsed data. This is the same way as pyang use. Note, that the automatic data type recognition is available only for the XML input.
Malformed XML data
Command and its output:
> data -x edit config-missing-key.xml libyang[0]: Parser fails around the line 19. libyang[0]: Mixed opening (nam) and closing (name) element tags. Failed to parse data.
State information in edit-config XML
Comand and its output:
> data -x edit config-unknown-element.xml libyang[0]: Parser fails around the line 24. libyang[0]: Unknown element "denied-operations". Failed to parse data.
Missing required element in NETCONF data
Comand and its output:
> data data-missing-key.xml libyang[0]: Parser fails around the line 6. libyang[0]: Missing required element "name" in "rule". Failed to parse data.
Malformed XML
Comand and its output:
> data data-malformed-xml.xml libyang[0]: Parser fails around the line 13. libyang[0]: Mixed opening (nam) and closing (rule) element tags. Failed to parse data.
Comand and its output:
> data data-malformed-xml2.xml libyang[0]: Parser fails around the line 7. libyang[0]: Mixed opening (module-name) and closing (name) element tags. Failed to parse data.
Bad value
Comand and its output:
> data data-out-of-range-value.xml libyang[0]: Parser fails around the line 24. libyang[0]: Value "-1" is out of range or length. Failed to parse data.
Preparation:
clear add ietf-netconf-acm-when2.yin
When condition is not satisfied since denied-operation = 0
Comand and its output:
> data data-acm.xml libyang[0]: Parser fails around the line 25. libyang[0]: When condition "../denied-operations > 0" not satisfied. libyang[0]: There are unresolved data items left. Failed to parse data.
Preparation:
clear add ietf-netconf-acm.yin
Print a pyang-style tree
Command and its output:
> print ietf-netconf-acm
module: ietf-netconf-acm
+--rw nacm
+--rw enable-nacm? boolean <true>
+--rw read-default? action-type <permit>
+--rw write-default? action-type <deny>
+--rw exec-default? action-type <permit>
+--rw enable-external-groups? boolean <true>
+--ro denied-operations ietf-yang-types:zero-based-counter32
+--ro denied-data-writes ietf-yang-types:zero-based-counter32
+--ro denied-notifications ietf-yang-types:zero-based-counter32
+--rw groups
| +--rw group* [name]
| +--rw name group-name-type
| +--rw user-name* user-name-type
+--rw rule-list* [name]
+--rw name string
+--rw group* union
+--rw rule* [name]
+--rw name string
+--rw module-name? union <*>
+--rw (rule-type)?
| +--:(protocol-operation)
| | +--rw rpc-name? union
| +--:(notification)
| | +--rw notification-name? union
| +--:(data-node)
| +--rw path node-instance-identifier
+--rw access-operations? union <*>
+--rw action action-type
+--rw comment? string
>
Obtain information about model
Command and its output:
> print -f info ietf-netconf-acm
Module: ietf-netconf-acm
Namespace: urn:ietf:params:xml:ns:yang:ietf-netconf-acm
Prefix: nacm
Desc: NETCONF Access Control Model.
Copyright (c) 2012 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD
License set forth in Section 4.c of the IETF Trust's
Legal Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC 6536; see
the RFC itself for full legal notices.
Reference:
Org: IETF NETCONF (Network Configuration) Working Group
Contact: WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com>
WG Chair: Bert Wijnen
<mailto:bertietf@bwijnen.net>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>
Editor: Martin Bjorklund
<mailto:mbj@tail-f.com>
YANG ver: 1.0
Deviated: no
Implement: yes
URI:
Revisions: 2012-02-22
Includes:
Imports: yang:ietf-yang-types
Typedefs: user-name-type
matchall-string-type
access-operations-type
group-name-type
action-type
node-instance-identifier
Idents:
Features:
Augments:
Deviation:
Data: container "nacm"
Print information about specific model part
Command and its output:
> print -f info -t /ietf-netconf-acm:nacm/ietf-netconf-acm:enable-nacm ietf-netconf-ac
Leaf: enable-nacm
Module: ietf-netconf-acm
Desc: Enables or disables all NETCONF access control
enforcement. If 'true', then enforcement
is enabled. If 'false', then enforcement
is disabled.
Reference:
Config: read-write
Status: current
Mandatory: no
Type: boolean
Units:
Default: true
If-feats:
When:
Must:
NACM: default-deny-all
Preparation:
clear add ietf-netconf-acm.yin
Print all user-name elements that occure in data
Command and its output:
> xpath -e //ietf-netconf-acm:user-name data-acm.xml Node XPath set: 1. ELEM "user-name" <user-name>krejci</user-name> 2. ELEM "user-name" <user-name>krejci</user-name> 3. ELEM "user-name" <user-name>xyz</user-name>
Print all data that satisfies condition
Command and its output:
> xpath -e //ietf-netconf-acm:user-name[text()="krejci"] data-acm.xml Node XPath set: 1. ELEM "user-name" <user-name>krejci</user-name> 2. ELEM "user-name" <user-name>krejci</user-name>
feature in YangPreparation:
clear add ietf-interfaces.yin add ietf-ip.yin add iana-if-type.yin
Note: This example also shows JSON output of the command.
Command and its output:
> feature -e * ietf-ip
> data -f json data-ip.xml
{
"ietf-interfaces:interfaces": {
"interface": [
{
"name": "eth0",
"description": "Wire Connection",
"type": "iana-if-type:ethernetCsmacd",
"enabled": true,
"ietf-ip:ipv4": {
"address": [
{
"ip": "192.168.1.15",
"netmask": "255.255.255.0"
},
{
"ip": "192.168.1.10",
"netmask": "255.255.255.0"
}
]
}
}
]
}
}