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Extensible YANG validator.


Build requirements:

  • erlang
  • libxml2-dev

Test requirements:

Installation of Yanger on macOS/Linux

1.Install erlang and libxml2-dev

  • macOS

Install erlang and coreutils using brew (if not present, install brew package manager)

# OS X 10.13.5 (High Sierra)
$ brew install erlang coreutils libxml2
  • Linux

Most linux distributions provide a package that can be installed using the system package manager,for example:

# Debian, Ubuntu, ...
$ apt-get install erlang libxml2-dev
# CentOS, RHEL, ...
$ yum install erlang libxml2-devel
# openSUSE
$ zypper install erlang libxml2-devel
# Fedora
$ dnf install erlang libxml2-devel

2.(optional)Install lux and pyang to verify test cases

  • install lux
# make local env
$ mkdir ~/local
$ cd ~/local
$ git clone

# export path
$ export PATH=$PATH:~/local/lux/bin
(put the above in .bash_profile or .profile)

# rebuild to use erlang
$ cd ~/local/lux
$ ./bin/lux --make

# test
$ ./bin/lux examples/intro.lux
  • git clone pyang and source the env bash
$ git clone
$ cd pyang
$ source


$ git clone
$ cd yanger
$ source
$ make

4.Running Unit Tests

$ make test

Installation of Yanger using Docker

Checkout this repository (described above) and build the image:

docker build -t mbj4668/yanger .

Execute the images as below:

$ docker run -it mbj4668/yanger
Usage: yanger [-h] [-v] [--print-error-code] [-p <path>]
              [-P <plugindir>] [-c] [--strict] [-e] [-W <warning>]
              [-w <no_warning>] [-E <error>] [-f <format>]
              [-t <transform>] [--max-status <max_status>]
              [--deviation-module <deviation_module>] [-F <features>]
              [-C <conformance>] [-o <outfile>] [--no-deviation-apply]
              [--print] [--print-all] <file>...

Execute the example below:

docker run -it -v ${PWD}:/workdir mbj4668/yanger -t expand -f swagger test_leaf.yang -o test_leaf_now_swagger.json

Sample Usage

To create a Swagger JSON file from a yang file, you must first have a yang file, for example, create the following test_leaf.yang file in your current working directory:

module test_leaf {
  namespace "";
  prefix ns;

container test_vars{
    leaf single_value
      type string;

Next you must tell yanger which format to output the yang into, in this example, it is the swagger JSON format, giving the new file output name test_leaf_now_swagger.json:

yanger -t expand -f swagger test_leaf.yang -o test_leaf_now_swagger.json

You will now have a JSON file created from the yang file:

$ more test_leaf_now_swagger.json
  "swagger": "2.0",
  "info": {
    "title": "test_leaf",
    "description": "",
    "version": "2018-10-15"
  "basePath": "/restconf",
  "tags": [
      "name": "root",

You can for example take the Swagger file to the Swaggerhub and auto create an SDK from it in a python flask format or other languages. The Swaggerhub requires free registration.

For more information about the yanger usage, please use the command yanger --help as below:

$ yanger --help
Usage: yanger [-h] [-v] [-V] [--print-error-code] [-p <path>]
              [-P <plugindir>] [--pa <pa>] [--pz <pz>] [-c]
              [--strict] [-e] [-W <warning>] [-w <no_warning>]
              [-E <error>] [-f <format>] [-t <transform>]
              [--max-status <max_status>]
              [--deviation-module <deviation_module>] [-F <features>]
              [--ignore-unknown-features <ignore_unknown_features>]
              [-C <conformance>] [-o <outfile>] [--no-deviation-apply]
              [--print] [--print-all] <file>...

  -h, --help                        Show this help message and exit.
  -v, --version                     Show version number and exit.
  -V, --verbose                     Verbose output.


Code style

Do not introduce trailing whitespace.

Do not introduce lines longer than 80 characters.

Do not use tabs for indentation.

Hint for emacs users:

(setq whitespace-style (quote (face trailing tabs lines)))

and use whitespace-mode.


If you wanted to use the erl-shell in order to debug you could:

erl -pa ./ebin


Extensible YANG validator




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