YANG

Table of Contents

• About YANG
• Generate a tree representation of a YANG module for quick visualization
  • Get some YANG modules
  • Pyang
    • Requirements
      • Install Pyang
      • Update the PATH env variable to use pyang
    • Useful Links
    • Generate a tree representation of a YANG module
  • gNMIc
    • Requirements
    • Useful Links
    • Generate paths from a YANG module
    • Generate a tree representation of a YANG module

About YANG

YANG is a data-model language defined by the IETF to model:

• The device configuration known as configuration data (writable data)
• The operational state known as state data (read-only status)

YANG determines the structure and syntax of the data.

The data model written in YANG are defined in YANG modules.

YANG modules can be categorized as:

• IETF defined YANG modules. Example: https://tools.ietf.org/html/draft-ietf-ospf-yang-29
• OpenConfig defined YANG modules. Published on https://github.com/openconfig/public/tree/master/release/models
• Network vendor defined YANG modules. Example: EOS data models https://github.com/aristanetworks/yang

YANG RFCs:

• https://tools.ietf.org/html/rfc6020 (YANG)
• https://tools.ietf.org/html/rfc7950 (YANG 1.1)

Generate a tree representation of a YANG module for quick visualization

Get some YANG modules

Before to use Pyang or gNMIc, let's get some YANG modules.

The YANG modules defined by OpenConfig are published on this repository https://github.com/openconfig/public/tree/master/release/models
Let's copy all the YANG files from the OpenConfig repository to a local directory

mkdir yang_modules
git clone https://github.com/openconfig/public.git
cp public/release/models/*.yang yang_modules/.
cp -R public/release/models/*/*.yang yang_modules/.
cp public/third_party/ietf/*.yang yang_modules/.
cd yang_modules/
ls

Pyang

We can use Pyang to generate a tree representation of YANG models for quick visualization.

Requirements

Install Pyang

Install Pyang on your automation setup

pip install pyang

pip list

Update the PATH env variable to use pyang

ls -l /home/arista/.local/bin/
echo $PATH
echo $HOME
export PATH="$HOME/.local/bin:$PATH"
echo $PATH

Useful Links

pyang source code https://github.com/mbj4668/pyang

Generate a tree representation of a YANG module

pyang openconfig-interfaces.yang -f tree
pyang openconfig-interfaces.yang -f tree --tree-path=/interfaces/interface/state
pyang openconfig-interfaces.yang -f tree --tree-depth=4

gNMIc

gNMIc is a gNMI client.
It can also be used to generate paths and tree representation from YANG modules.

Requirements

Install gNMIc on your automation setup

bash -c "$(curl -sL https://get-gnmic.kmrd.dev)"

gnmic version
gnmic help

Useful Links

gNMIc documentation https://gnmic.kmrd.dev/
gNMIc source code https://github.com/karimra/gnmic

Generate paths from a YANG module

gnmic generate path --file openconfig-interfaces.yang --state-only
gnmic generate path --file openconfig-interfaces.yang --types

Generate a tree representation of a YANG module

gnmic generate --file openconfig-interfaces.yang
gnmic generate --file openconfig-interfaces.yang --json