Exploring Nornir - Part One

Jul 24, 2019 19:23 · 486 words · 3 minute read technical nornir napalm

This post is the first in a series of posts in exploring the Nornir automation framework

Exploring Nornir - Part One

Over a year ago, I came across an alternative automation framework called Brigade, now renamed Nornir. At the time, I was about to embark on learning Ansible but after having a cursory look at this framework, it had shown great promise.

Recently, I’ve had a chance to revisit Nornir and use it for a problem I am trying to solve.

What is Nornir?

To quote the official documentation:

Nornir is an automation framework written in python to be used with python.

This doesn’t seem particularly impressive or noteworthy if you don’t come from a Python background, but please read on and I will elaborate on the benefits of this simple statement.

How does Nornir work?

Nornir uses an inventory and the inheritance model to store tiered information about your inventory. This functionality is akin to what Ansible offers.

From here, Nornir can execute tasks using various plugins to carry out automation tasks as required.

Why use Nornir?

There are some differentiators which make Nornir a interesting use case.

1) It’s fast

Nornir allows the ability for parallel task execution, allowing you full flexibility to execute at speed or perform standard looping on a per-task basis.

Whilst developing a Nornir project, I would often develop a task using a simple loop, then reconfigure to take advantage of parallelization.

Compared to Ansible, this feature alone can save a significant amount of time.

2) Powerful inventory filtering

Nornir provides the ability to apply complex filtering to your inventory, allowing you to be precise yet elegant in classifying similar hosts to perform some tasks.

In future, I will dedicate a post to filtering in Nornir to solve some automation challenges.

3) Utilise existing tools and modules

Being pure python, you can leverage all your existing tools. I use Pycharm for all other Python projects which is a great IDE for Python.

You can also use code auditing and linting tools like Pylama or Black against your Nornir projects.

Finally, rather than scouring the Internet for obscure custom modules or writing them yourself, you can leverage the thousands of existing Python modules to perform a task not provided by Nornir.

4) Did I mention it’s written in Python?

There is most likely someone in your company who has some Python knowledge who may not even be in networking or security. Starting a conversation about this project may help you share some common ground and break down some barriers.

If that doesn’t work, there are many great resources for Python, with a network focus. I’ve listed a few below:

Python for Network Engineers - by Kirk Byers
Mastering Python Networking - by Eric Chou
Python 3 Network Programming - by Mihai Catalin Teodosiu

In the next post, I will explore and use Nornir to solve a common challenge within most environments.