This text provides several use-case of the yanglint(1) interactive
mode. For basic information about the yanglint(1) usage, please see
the man page.
The examples are supposed to be went through one by one. Some of the examples suppose the specific schemas loaded in some of the previous example is still loaded. If an addition work is need, the preparation part in the example provides information what to do.
To show all available command of the yanglint(1), use the help command:
> help
Available commands:
help Display commands description
add Add a new module from a specific file
load Load a new schema from the searchdirs
print Print a module
data Load, validate and optionally print instance data
list List all the loaded modules
feature Print all features of module(s) with their state
searchpath Print/set the search path(s) for schemas
clear Clear the context - remove all the loaded modules
verb Change verbosity
debug Display specific debug message groups
quit Quit the program
? Display commands description
exit Quit the program
To show the information about the specific command, use the help command in
combination with the command name you are interested in:
> help searchpath
Usage: searchpath [--clear] [<modules-dir-path> ...]
Set paths of directories where to search for imports and includes
of the schema modules. Subdirectories are also searched. The current
working directory and the path of the module being added is used implicitly.
The 'load' command uses these paths to search even for the schema modules
to be loaded.
The input files referred in this document are available together with this document.
Let's have two data models module1.yang and module1b.yang. They differ in the module name but their namespaces are the same.
Preparation:
> clear
> add module1.yang
> list
Output:
List of the loaded models:
i ietf-yang-metadata@2016-08-05
I yang@2022-06-16
i ietf-inet-types@2013-07-15
i ietf-yang-types@2013-07-15
I ietf-yang-schema-mount@2019-01-14
I module1
Command and its output:
> add module1b.yang
libyang[0]: Two different modules ("module1" and "module1b") have the same namespace "urn:yanglint:module".
libyang[0]: Parsing module "module1b" failed.
YANG/YIN syntax
module2.yin contains a syntax error.
There is a bad syntax of the type statement in YIN file.
<type value="string"/>
instead of
<type name="string"/>
Preparation:
> clear
Command and its output:
> add module2.yin
libyang[0]: Unexpected attribute "value" of "type" element. (path: Line number 8.)
libyang[0]: Parsing module "module2" failed.
Similarly, there is a typo in module2.yang.
XPath errors
libyang and yanglint(1) is able to detect also errors in XPath expressions.
In module3.yang the must expression refers to the node which does not exists.
Preparation:
> clear
Command and its output:
> add module3.yang
libyang[1]: Schema node "a" for parent "/module3:c" not found; in expr "../c/a" with context node "/module3:m".
Note that libyang prints only a warning in this case because it is not specified that XPath expressions must refer to existing nodes.
Preparation:
> clear
> add ietf-netconf-acm.yang
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 -t config datastore.xml
We use option -t to specify type of the data in datastore.xml. By the
config value we declare that the input file contains all the configuration
data (with at least all the mandatory nodes as required by the loaded schemas),
but without the status data. More examples of different data types will follow.
Command and its output:
> data -t config datastore.xml
libyang[0]: No module with namespace "urn:ietf:params:xml:ns:yang:ietf-interfaces" in the context. (path: Line number 20.)
YANGLINT[E]: Failed to parse input data file "datastore.xml".
Note that in case of working with complete datastore including the status data
(no -t option is specified), yanglint(1) has to add status data from its
internal ietf-yang-library module.
RPC and RPC-reply
It is possible to validate RPCs and their replies as well.
Peparation:
> clear
> add module4.yang
Command and its output:
> data -t rpc rpc.xml
Reply to this RPC can be validated too, but it must be nested in the original RPC element.
Command and its output:
> data -t reply ../tools/lint/examples/rpc-reply.xml
action and action-reply
Actions are validated the same way as RPCs except you need to be careful about the input file structure. No NETCONF-specific envelopes are expected.
Preparation
> clear
> add module4.yang
Command and its output:
> data -t rpc action.xml
Command and its output:
> data -t rpc action-reply.xml action.xml
notification
Both top-level and nested notification can be validated.
Preparation
> clear
> add module4.yang
Command and its output:
> data -t notif notification.xml
Command and its output:
> data -t notif nested-notification.xml
Multiple top-level elements in a single document
As a feature and in conflict with the XML definition, yanglint(1) (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:
> clear
> add ietf-netconf-acm.yang
> add ietf-interfaces.yang
> add ietf-ip.yang
> add iana-if-type.yang
Command and its output:
> data -t config 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(1), this is done
via -t 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(1) to recognize the data type automatically by the additional top-level
elements added to the parsed data. This is the same way as pyang(1) uses. Note,
that the automatic data type recognition is available only for the XML input.
Malformed XML data
Command and its output:
> data -t edit config-missing-key.xml
libyang[0]: Node "nam" not found as a child of "group" node. (path: Schema location "/ietf-netconf-acm:nacm/groups/group", data location "/ietf-netconf-acm:group", line number 19.)
YANGLINT[E]: Failed to parse input data file "config-missing-key.xml".
State information in edit-config XML
Command and its output:
> data -t edit config-unknown-element.xml
libyang[0]: Unexpected data state node "denied-operations" found. (path: Schema location "/ietf-netconf-acm:nacm/denied-operations", data location "/ietf-netconf-acm:nacm", line number 24.)
YANGLINT[E]: Failed to parse input data file "config-unknown-element.xml".
Missing required element in NETCONF data
Command and its output:
> data data-missing-key.xml
libyang[0]: List instance is missing its key "name". (path: Schema location "/ietf-netconf-acm:nacm/rule-list/rule", data location "/ietf-netconf-acm:rule", line number 10.)
YANGLINT[E]: Failed to parse input data file "data-missing-key.xml".
Malformed XML
Command and its output:
> data data-malformed-xml.xml
libyang[0]: Node "nam" not found as a child of "rule" node. (path: Schema location "/ietf-netconf-acm:nacm/rule-list/rule", data location "/ietf-netconf-acm:rule", line number 8.)
YANGLINT[E]: Failed to parse input data file "data-malformed-xml.xml".
Command and its output:
> data data-malformed-xml2.xml
libyang[0]: Child element "module-name" inside a terminal node "name" found. (path: Schema location "/ietf-netconf-acm:nacm/rule-list/rule/name", data location "/ietf-netconf-acm:name", line number 7.)
YANGLINT[E]: Failed to parse input data file "data-malformed-xml2.xml".
Bad value
Command and its output:
> data data-out-of-range-value.xml
libyang[0]: Value "-1" is out of type uint32 min/max bounds. (path: Schema location "/ietf-netconf-acm:nacm/denied-operations", data location "/ietf-netconf-acm:nacm", line number 24.)
YANGLINT[E]: Failed to parse input data file "data-out-of-range-value.xml".
Preparation:
> clear
> add ietf-netconf-acm-when.yang
When condition is not satisfied since denied-operation = 0
Command and its output:
> data data-acm.xml
libyang[0]: When condition "../denied-operations > 0" not satisfied. (path: Schema location "/ietf-netconf-acm-when:nacm/denied-data-writes", data location "/ietf-netconf-acm-when:nacm/denied-data-writes".)
YANGLINT[E]: Failed to parse input data file "data-acm.xml".
Preparation:
> clear
> add ietf-netconf-acm.yang
Print a pyang-style tree
Command and its output:
> print ietf-netconf-acm
module: ietf-netconf-acm
+--rw nacm
+--rw enable-nacm? boolean
+--rw read-default? action-type
+--rw write-default? action-type
+--rw exec-default? action-type
+--rw enable-external-groups? boolean
+--ro denied-operations yang:zero-based-counter32
+--ro denied-data-writes yang:zero-based-counter32
+--ro denied-notifications yang: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
Print information about specific model part
Command and its output:
> print -f info -P /ietf-netconf-acm:nacm/ietf-netconf-acm:enable-nacm ietf-netconf-acm
leaf enable-nacm {
ietf-netconf-acm:default-deny-all;
type boolean;
default "true";
config true;
status current;
description
"Enables or disables all NETCONF access control
enforcement. If 'true', then enforcement
is enabled. If 'false', then enforcement
is disabled.";
}
Preparation:
> clear
> add ietf-interfaces.yang
> add ietf-ip.yang -F ietf-ip:*
> add iana-if-type.yang
Note: This example also shows JSON output of the command.
Command and its output:
> feature ietf-ip
ietf-ip features:
ipv4-non-contiguous-netmasks (on)
ipv6-privacy-autoconf (on)
> data -f json -t config 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"
}
]
}
}
]
}
}
In these examples the non-interactive yanglint is used to simplify creating the context, a yang-library data file is
used. The working directory is libyang/tools/lint/examples and libyang must be installed.
Print tree output of a model with Schema Mount
Command and its output:
$ yanglint -f tree -p . -Y sm-context-main.xml -x sm-context-extension.xml sm-main.yang
module: sm-main
+--mp root* [node]
| +--rw node string
+--mp root2
+--rw root3
+--mp my-list* [name]
+--rw things/* [name]
| +--rw name -> /if:interfaces/if:interface/if:name
| +--rw attribute? uint32
+--rw not-compiled/
| +--rw first? string
| +--rw second? string
+--rw interfaces@
| +--rw interface* [name]
| +--rw name string
| +--rw type identityref
+--rw name string
Validating and printing mounted data
Command and its output:
$ yanglint -f json -t config -p . -Y sm-context-main.xml -x sm-context-extension.xml sm-data.xml
{
"ietf-interfaces:interfaces": {
"interface": [
{
"name": "eth0",
"type": "iana-if-type:ethernetCsmacd"
},
{
"name": "eth1",
"type": "iana-if-type:ethernetCsmacd"
}
]
},
"sm-main:root3": {
"my-list": [
{
"name": "list item 1",
"sm-extension:things": [
{
"name": "eth0",
"attribute": 1
}
]
}
]
}
}