ygot

Overview

ygot is a collection of Go utilities that can generate Go structures based off of YANG modules. In the demo we are going to generate go code based off of the openconfig-system model using ygot.

Demo Actions

• Import the necessary YANG files for openconfig-system to create a hostname.
• The hostname will be printed out and stored within the system.json file.
• Using the Arista gNMI binary we will configure a device with the ceos1 hostname.

Clone this repo

git clone https://github.com/aristanetworks/openmgmt && cd openmgmt/src/ygot

Install ygot

go get github.com/openconfig/ygot

Check to see if all of the current YANG files are accurate

tree -f yang/

Reveal output

├── yang/openconfig-aaa-radius.yang
├── yang/openconfig-aaa-tacacs.yang
├── yang/openconfig-aaa-types.yang
├── yang/openconfig-aaa.yang
├── yang/openconfig-alarms.yang
├── yang/openconfig-alarm-types.yang
├── yang/openconfig-extensions.yang
├── yang/openconfig-inet-types.yang
├── yang/openconfig-license.yang
├── yang/openconfig-messages.yang
├── yang/openconfig-platform-types.yang
├── yang/openconfig-platform.yang
├── yang/openconfig-procmon.yang
├── yang/openconfig-system-logging.yang
├── yang/openconfig-system-management.yang
├── yang/openconfig-system-terminal.yang
├── yang/openconfig-system.yang
├── yang/openconfig-types.yang
└── yang/openconfig-yang-types.yang

Run ygot

go run $GOPATH/src/github.com/openconfig/ygot/generator/generator.go      \
  -path=yang -output_file=pkg/oc.go -package_name=oc -generate_fakeroot   \
  -fakeroot_name=device -compress_paths=true  yang/openconfig-system.yang

Check the contents of pkg/oc.go

pkg
└── oc.go

oc.go is the necessary go import / package for openconfig-system. Looking at the Device struct within pkg/oc.go

type Device struct {
  Component map[string]*Component `path:"components/component" module:"openconfig-platform"`
  Messages  *Messages `path:"messages" module:"openconfig-messages"`
  System *System `path:"system" module:"openconfig-system"`
}

Looking at the System struct we can see the Hostname field.

type System struct {
  Hostname *string `path:"config/hostname" module:"openconfig-system"`
}

We need to fill in the Hostname field and pass it through the EmitJSON function so we can render this model with the correct information which can be found in main.go.

Run the go code

go run main.go

Output:

Reveal output

{
  "openconfig-system:system": {
    "config": {
      "hostname": "ceos1"
    }
  }
}

The output is also within `config/hostname.json` which is the same as the printed version.

Change the hostname on a device

gnmi -addr ${DEVICEIP}:6030 -username admin -password admin update '/' config/hostname.json

The device should now have the ceos1 hostname.