Table Of ContentNetwork Automation with Go
Learn how to automate network operations and build
applications using the Go programming language
Nicolas Leiva
Michael Kashin
BIRMINGHAM—MUMBAI
Network Automation with Go
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For my wife Catalina and daughter Renata, whose constant support and encouragement made this
book possible.
– Nicolas Leiva
To the memory of my Mother, for her love, support and inspiration.
– Michael Kashin
Contributors
About the authors
Nicolas Leiva is a staff solutions architect at Red Hat. In his role, he helps customers of all business
sizes to automate the provisioning and operation of IT infrastructure, services, and applications.
Prior to that, he worked in the networking industry for 15 years, becoming a Cisco Certified Design
Expert (CCDE) and Cisco Certified Internetwork Expert (CCIE). He is passionate about writing
open source software in Go with a keen interest in cloud technologies.
I want to thank my parents, Rafael and Maria Estela, for guiding me in the right direction to get here
and be the person I am today.
Michael Kashin is a cloud infrastructure solutions architect, currently working in the networking
business unit of NVIDIA. Throughout his career, he held multiple roles ranging from network operations,
through software development, to systems architecture and design. He enjoys breaking the boundaries
between different disciplines and coming up with creative solutions to satisfy business needs and solve
technical problems in the most optimal way. He is a prolific open source contributor and writer, with
much of his work focused on cloud-native infrastructure, automation, and orchestration.
I want to thank my wife for putting up with me spending endless hours writing this book, and for
looking after the kids all this time.
About the reviewers
John McGovern holds a first-class Honours Bachelor of Science degree (BSc Hons) in cybersecurity
and networking from Glasgow Caledonian University. He is a technical instructor for CBT Nuggets
and has developed a wide library of training around network automation, with a focus on Python
programming, including Python-based libraries such as Nornir, Scrapli, and NAPALM. John is also a
regular panelist on the Network Automation Hangout podcast and an active contributor to the Cisco
DevNet Code Exchange program.
I would like to primarily thank the authors, Nicolas and Michael, for all of their great work in
creating this fantastic learning resource. You both are incredible. I would also like to thank Stephen
Hendry and Kamil Stachura for all of the help, guidance, and camaraderie over these last few years
automating networks. And lastly, to Carl Montanari, Dmitry Figol, and Roman Dodin – you guys are
the best; thank you for everything you do.
Chris Luke has been engineering networks since the early days of the dial-up internet, using home-
grown software development as a tool to improve the reliability of those services. Chris is currently at
Comcast, modernizing the configuration management and automation practices of the core network.
He also leads a program teaching network engineers how to bring code to the day job.
Chris is currently a maintainer for the OpenConfig project and a committer for the FD.io VPP project.
He has previously been the chairperson of the OpenDaylight Advisory Group and has contributed
networking code to FreeBSD and Linux, as well as to the Bird and Quagga routing daemons and many
other open source projects.
Table of Contents
Preface xiii
Part 1: The Go Programming Language
1
Introduction 3
Technical requirements 4 Ease of use 17
Networking and Go 4 Memory management 18
Syntax 18
Why Go? 5
Failure handling 18
Non-technical reasons 5
Concurrency 19
The future of Go 8 Community 19
Technical reasons 8
Installing Go on your computer 20
Go for networking 13
Windows 20
Go versus Python 16 Mac 20
Code execution 16 Linux 21
Type system 17
Summary 21
Performance 17
Further reading 21
2
Go Basics 25
Technical requirements 26 Packages 31
What is Go? 26 Go modules 32
Importing packages 33
Go Proverbs 29
Comments 34
Go source code files 30
Names 36
viii Table of Contents
Executing your Go code 37 Mod 46
Get 49
Running Go programs online 38
Install 49
The Go Playground 38
Fmt 50
The Go Play Space 40
Test 50
A look into the Future 42
Env 52
The Go tool 43
Summary 53
Build 44
Further reading 53
Run 46
3
Getting Started with Go 55
Technical requirements 55 Interfaces 95
Go’s type system 56 Network automation example 96
Basic types 57 Standard library example 98
Container types 63 Interfaces as contracts 100
User-defined types 69 Input and output operations 101
Arithmetic, comparison, and logical The io.Reader interface 101
operators 71 The io.Writer interface 102
Arithmetic operators 71 The io.Copy function 104
Logical operators 77 Composition 106
Comparison operators 78 Decoding and encoding 107
Control flow 79 Decoding 107
for loops 79 Encoding 114
Conditional statements 81 Concurrency 115
goto statements 83
Goroutines 116
Functions 85 Channels 122
Function arguments 86 Channels and Timers 124
Error handling 90 Shared data access 126
Methods 91 Concurrency caveats 130
Variadic functions 92 Summary 130
Closures 93
Further reading 131
Defer 94
Table of Contents ix
4
Networking (TCP/IP) with Go 135
Technical requirements 136 The transport layer 155
The link layer 136 UDP ping application 156
Network interfaces 136 The application layer 161
Ethernet 139
Working with an HTTP client 162
The internet layer 143 Working with an HTTP (server) 165
The net package 143 Summary 169
The New netip package 146
Further reading 169
Working with IP addresses 149
Route lookups 150
Part 2: Common Tools and Frameworks
5
Network Automation 173
Technical requirements 173 Network state analysis 179
What is network automation? 174 Network audits and reporting 181
Why network automation exists 174 Systems approach 182
Bottom-up view 175 Closed-loop automation 182
Top-down view 176 Demo application 183
Automating network operation tasks 177 Summary 188
Configuration management 177 Further reading 188
6
Configuration Management 189
Technical requirements 190 Interacting with network devices via
Environment setup 190 SSH 192
Creating the topology 190 Describing the network device configurations 193
Using Go’s SSH package to access network
