Understanding RESTCONF

Basic Concepts of RESTCONF

• Derived from Netconf
• Model definition in YANG
• The request/response data is XML or JSON
• Using HTTPS methods(GET / PATCH / POST / DELETE / PUT)
• RESTCONF URI format: /<api-entry>/<resource-type>/<yang-module:resource>

Yang model

• RESTCONF uses YANG as its modeling language
• Defined in rfc6020

Enabling RESTCONF on IOS-XE

haifeli-C9800#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
haifeli-C9800(config)#restconf
haifeli-C9800(config)#ip http  secure-server
haifeli-C9800(config)#end
haifeli-C9800#wr
Building configuration...
[OK]
haifeli-C9800#

PYANG

pyang is a YANG validator, transformator and code generator, written in python. It can be used to validate YANG modules for correctness, to transform YANG modules into other formats, and to generate code from the modules.

Installation

It is recommended to use pyang in a linux environment.

pip install pyang

Tree output

The command is as follows.

pyang -f tree <filename>

Example:

root@yang-explorer-1:/cisco/xe/1731# pyang -f tree Cisco-IOS-XE-memory-oper.yang
module: Cisco-IOS-XE-memory-oper
  +--ro memory-statistics
  |  +--ro memory-statistic* [name]
  |     +--ro name             string
  |     +--ro total-memory?    uint64
  |     +--ro used-memory?     uint64
  |     +--ro free-memory?     uint64
  |     +--ro lowest-usage?    uint64
  |     +--ro highest-usage?   uint64
  +--rw schema-metadata-Cisco-IOS-XE-memory-oper
  |  +--rw json-metadata-leaf?   empty
  +--rw gnmi-model-data
root@yang-explorer-1:/cisco/xe/1731#

Curl

The command is as follows.

curl -k -u username:password <link>

Example:

C:\Users\test>curl -k -u admin:Cisco123 https://10.106.63.111/restconf/data/Cisco-IOS-XE-native:native/interface/Vlan=62/ip/address/primary

<primary xmlns="http://cisco.com/ns/yang/Cisco-IOS-XE-native"  xmlns:ios="http://cisco.com/ns/yang/Cisco-IOS-XE-native">
  <address>10.106.62.111</address>
  <mask>255.255.255.0</mask>
</primary>

C:\Users\test>

Postman

Postman is a powerful API debugging tool that we can use to send HTTP requests.

Python script

Usually using the requests module to send HTTP requests.

import requests

requests.packages.urllib3.disable_warnings()

host = '10.106.53.53'
user = 'admin'
password = 'Cisco123'

url = "https://{h}/restconf/data/Cisco-IOS-XE-process-cpu-oper:cpu-usage/cpu-utilization".format(
    h=host)

headers = {'Content-Type': 'application/yang-data+json',
           'Accept': 'application/yang-data+json'}

response = requests.request(
    "GET",
    url,
    auth=(
        user,
        password),
    headers=headers,
    verify=False)

print(response.json()[
      'Cisco-IOS-XE-process-cpu-oper:cpu-utilization']['one-minute'])

Axios

If we are developing a web application, we can use axios to send HTTP requests.

Installation

Using npm

npm install axios

Using unpkg CDN

<script src="https://unpkg.com/axios/dist/axios.min.js"></script>

Example

The following is an Vue.js example.

<script>
axios.defaults.withCredentials = true;

const url =
  "https://10.106.53.53/restconf/data/Cisco-IOS-XE-process-cpu-oper:cpu-usage/cpu-utilization/five-seconds";

const config = {
  data: {},
  headers: {
    Accept: "application/yang-data+json",
  },
};

export default {
  data() {
    return {
      cpuUsage: [],
    };
  },
  methods: {
    getData: function () {
      axios.get(url, config).then((response) => {
        console.log(
          response["data"]["Cisco-IOS-XE-process-cpu-oper:five-seconds"]
        );
        this.cpuUsage.push(
          response["data"]["Cisco-IOS-XE-process-cpu-oper:five-seconds"]
        );
      });
    },
  },
  computed: {
    results() {
      return this.cpuUsage;
    },
  },
};
</script>

References

RESTCONF Protocol
Introduction to RESTCONF
RESTCONF Configuration