Use Custom YANG RPCs on Devices Running Junos OS

You can add YANG data models that define custom RPCs on supported devices running Junos OS. Creating custom RPCs enables you to precisely define the input parameters and operations and the output fields and formatting for your specific operational tasks on those devices.

To add an RPC to a device running Junos OS, download the YANG module that defines the RPC, along with any required action scripts to the device, and add the files to a new or existing YANG package by issuing the request system yang add or request system yang update operational command. For detailed information about adding YANG modules to devices running Junos OS, see Manage YANG Packages, Modules, and Scripts on Junos Devices.

After you add the modules and action scripts to the device, you can execute the RPC either locally, provided that the RPC definition includes the junos:command statement, or remotely. To execute an RPC in the Junos OS CLI, issue the command defined by the RPC’s junos:command statement. To execute an RPC remotely, use the RPC name in an RPC request operation.

Consider the following YANG module and RPC definition:

module sw-info {
  namespace "http://yang.juniper.net/examples/rpc-cli";
  prefix rpc-cli;

  import junos-extension {
    prefix junos;
  }

  rpc get-sw-info {
    description "Show software information";
    junos:command "show sw-info" {
       junos:action-execute {
         junos:script "sw-info.py";
      }
    }
    input {
      leaf routing-engine {
        type string;
        description "Routing engine for which to display information";
      }
      ...
    }
    output {
      ...
    }
  }
}

To execute this RPC in the Junos OS CLI, issue the show sw-info command defined by the junos:command statement, and include any required or optional input parameters. For example:

user@host> show sw-info routing-engine re0

To execute this RPC remotely, send an RPC request that uses the RPC name for the request tag, and include any required or optional input parameters.

<rpc>
   <get-sw-info>
     <routing-engine>re0</routing-engine>
   </get-sw-info>
</rpc>

When you execute a custom RPC, the device invokes the action script that is defined in the junos:script statement, which in this example is the sw-info.py script. An RPC’s action script should emit any necessary XML elements for that RPC’s output.

When you execute an RPC in the Junos OS CLI by issuing the command defined by the junos:command statement, the device displays the RPC output, if there is any, using the CLI formatting defined by the RPC. If the RPC does not define CLI formatting, the device does not display any output for that RPC in the CLI. However, you can still display the RPC’s XML output in the CLI by appending | display xml to the command.

user@host> show sw-info routing-engine re0 | display xml

When you execute an RPC remotely, the RPC output defaults to XML. However, you can specify a different output format by including the format attribute in the opening request tag of the RPC. To display CLI formatting, provided that the RPC defines this format, set the format attribute to text or ascii. To display the output in JavaScript Object Notation (JSON), set the format attribute to json. For example:

<rpc>
   <get-sw-info format="text">
     <routing-engine>re0</routing-engine>
   </get-sw-info>
</rpc>