Reimagining The CLI with Python

The Command Line Interface. A near 60-year old technology a majority of the world’s networking teams solely rely on for their architectures, designs, monitoring, operations, and support. Most of us, pre-DevNet, have been raised and groomed to become CLI wizards and warriors with a super-hero level of ability being the standard expectation.

Command-line interface – Wikipedia

But the dirty secret is the CLI sucks and we are literally using a tool that was released half-a-century-ago. Imagine if COBOL (1959) was still the only programming language in the world ? Welcome to Enterprise IT Networks – here is the CLI – good luck to you!

Well today I am going to reimagine a modern, next-generation, CLI using Python and see if I can breathe new-life into our very old friend the CLI.

This post in Meme format

Why does the CLI still suck?

It is grounded in it’s historical roots. Take for example that the original IOS had 256kB of memory with pre-Pentium chipsets! So they needed a lean and text-driven CLI to configure and operate the early routers and switches.

Cisco IOS – Wikipedia

It is also why the modern next-generation devices come with a REST API that supports RESTCONF, NETCONF, and YANG models – they want to you get away from the CLI and move towards a modern approach.

But what about the legacy fleet? The brownfield? What if my staff are religious about the CLI ? Or fearful to learn REST, start using Postman and JSON, or even dreaded network automation like Ansible or Python ?

Culture will change over time but we need an easy, accessible, and palatable alternate to SSH’ing into devices one by one to perform CLI operations.

Take the most basic, first-to-be-run on any device, command show version.

In this video, the first I’ve ever done, I explore how, using Python, pyATS, Genie, Jinja2 Templates, and Cloud REST APIs, we can create the next-generation show version command – check it out!

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