# YANGLINT - Interactive Mode Examples 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] [ ...] Set paths of directories where to search for imports and includes of the schema modules. 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. ## Duplicit Data Model Let's have two data models [module1.yang](./module1.yang) and [module1b.yang](./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 Data Model Validation **YANG/YIN syntax** `module2.yin` contains a syntax error. There is a bad syntax of the `type` statement in YIN file. ``` ``` instead of ``` ``` 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. ## Data Validation 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". ``` ## Validation of "when" Statement in Data 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". ``` ## Printing a Data Model 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."; } ``` ## Usage of `feature` in Yang 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" } ] } } ] } } ```