Eric Chou - Mastering Python Networking

Mastering Python Networking

Third Edition

Your one-stop solution to using Python for network automation, programmability, and DevOps

Eric Chou

BIRMINGHAM - MUMBAI

Mastering Python Networking

Third Edition

Copyright 2020 Packt Publishing

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Producer: Tushar Gupta

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First published: June 2017

Second edition: August 2018

Third edition: January 2020

Production reference: 1280120

Published by Packt Publishing Ltd.

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ISBN 978-1-83921-467-7

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For my wife Joanna and children, Mikaelyn and Esmie. For my parents, who lit up the fire in me many years ago.

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Foreword

This book you are holding in your hand or are reading on your screen has a power that can be yours if you take time to study it. Much like Thor's hammer or Iron Man's suit, programming is a superpower that amplifies your existing knowledge and skill set.

Many people feel, or are told, that they should learn programming and Python for their own sake. Programming skills are in demand, so you should be a programmer. That is probably good advice. But better advice would be to answer the question, "How can you take your existing expertise and leap ahead of peers by automating and extending that experience with software skills?" This book aims to do just that for network professionals. You'll learn Python in the context of network configuration, administration, monitoring, and more.

If you are tired of logging in and typing a bunch of commands to configure your network, Python is for you. If you need to be certain that the network configuration is solid and repeatable, Python is for you. If you need to monitor, in real-time, what is happening on the network, well, you guessed it, Python is for you.

You are probably in agreement about learning software skills that can be applied to network engineering. After all, terms like Software-Defined Networking (SDN) have been all the buzz in the last few years. But why Python? Maybe you should learn JavaScript or Go or some other language. Maybe you should just double down on Bash and shell scripting.

Python is well-suited for network engineering for two reasons.

First, as Eric will demonstrate throughout this book, there are many Python libraries (sometimes called packages) designed specifically on network engineering. A focused search over at https://pypi.org for the network topic turns up over 500 different libraries for network automation and monitoring. With libraries such as Ansible, you can create complex network and server configurations declaratively using simple configuration files.

Using Pexpect or Paramiko, you'll be able to program against remote legacy systems as if they had their own scripting API. If the gear you're configuring has an API, chances are you can use a purpose-built Python library to work with it. So clearly, Python is well-suited for the job.

Second, Python is special amongst programming languages. Python is what I call a full spectrum language. My definition of this term is that it is both a language that is incredibly easy to get started (print("hello world") anyone?) and also very powerful, being the technology behind incredible software such as youtube.com .

This is not normal. We have solid beginner languages for quickly building software. Visual Basic comes to mind here. So does MATLAB and other commercial languages. Yet, when these are pushed too far, they fall down badly. Can you imagine Linux, Firefox, or an intensive video game created with any of these? No way.

At the other end of the spectrum, we also have very powerful languages such as C++, .NET, Java, and many others. C++ is, in fact, the language used to build some Linux kernel modules and large open source software such as Firefox to some degree. Yet, these languages are not beginner friendly. You have to learn about pointers, compilers, linkers, headers, classes, accessibility (public/private), and so on just to get started.

Python lives in both realms. On one hand it is incredibly easy to be productive with just a few lines of code and simple programming concepts. On the other, it is increasingly the language of choice for some of the world's most significant software; such as that behind YouTube, Instagram, Reddit, and others. Microsoft chose Python as their language to implement the command line interface (CLI) for Azure (although you don't have to know or use Python to use their CLI, of course).

So, here's the deal. Programming is a superpower. It can take your network engineering expertise and launch it into the stratosphere. Python is one of the world's fastest growing and most popular programming language. Additionally, Python has many highly polished libraries for working with networks in many facets. This book,