I have been blown away by the response Go Programming Blueprints has received, both from newcomers to Go, as well as well-respected titans of the community. The positive feedback has inspired me to do this second edition, where the code has been updated to the latest thinking and three new chapters have been added. Thanks to the contributions and questions from readers on the GitHub repository (https://github.com/matryer/goblueprints), I have been able to address some errors, fix some bugs, and clear some things up. See the README file on GitHub for a complete list of their names.
I decided to write Go Programming Blueprints because I wanted to expel the myth that Go, being a relatively young language and community, is a bad choice to write and iterate on software quickly. I have a friend who knocks out complete Ruby on Rails apps in a weekend by mashing up pre-existing gems and libraries; Rails as a platform has become known for enabling rapid development. As I do the same with Go and the ever-growing buffet of open source packages, I wanted to share some real-world examples of how we can quickly build and release software that performs well from day one and is ready to scale when our projects take off in a way that Rails cannot compete with. Of course, most scalability happens outside the language, but features such as Go's built-in concurrency mean you can get some very impressive results from even the most basic hardware, giving you a head start when things start to get real.
This book explores some very different projects, any of which can form the basis of a genuine startup. Whether it's a low-latency chat application, a domain name suggestion tool, a social polling and election service built on Twitter, or a random night out generator powered by Google Places, each chapter touches upon a variety of problems that most products or services written in Go will need to address. The solutions I present in this book are just one of many ways to tackle each project, and I will encourage you to make up your own mind about how I approached them. The concepts are more important than the code itself, but you'll hopefully pick up a few tips and tricks here and there that can go into your Go toolbelt.
New to this second edition, we will explore some practical modern architectural thinking, such as how to build for Google App Engine, what a microservice looks like, and how to package up our code with Docker and deploy to anywhere.
The process by which I wrote this book may be interesting because it represents something about the philosophies adopted by many agile developers. I started by giving myself the challenge of building a real deployable product (albeit a simple one; a minimum viable product, if you will) before getting stuck into it and writing a version 1. Once I got it working, I would rewrite it from scratch. It is said many times by novelists and journalists that the art of writing is rewriting; I have found this to be true for software as well. The first time we write a piece of code, all we are really doing is learning about the problem and how it might be tackled, as well as getting some of our thinking out of our heads and onto paper, or into a text editor. The second time we write it, we are applying our new knowledge to actually solve the problem. If you've never tried this, give it a shot—you might find that the quality of your code shoots up quite dramatically as I did. It doesn't mean the second time will be the last time—software evolves and we should try to keep it as cheap and disposable as possible so we don't mind throwing pieces away if they go stale or start to get in the way.
I write all of my code following Test-driven development (TDD) practices, some of which we will do together throughout the book and some you'll just see the result of in the final code. All of the test code can be found in the GitHub repositories for this book, even if it's not included in print.
Once I had my test-driven second versions completed, I started writing the chapter describing how and why I did what I did. In most cases, the iterative approach I took is left out of the book because it would just add pages of tweaks and edits, which would probably just become frustrating for the reader. However, on a couple of occasions, we will iterate together to get a feel of how a process of gradual improvements and small iterations (starting and keeping it simple and introducing complexity only when absolutely necessary) can be applied when writing Go packages and programs.
I moved to the United States from England in 2012, but that is not why the chapters are authored in American English; it was a requirement from the publisher. I suppose this book is aimed at an American audience, or perhaps it's because American English is the standard language of computing (in British code, properties that deal with color are spelled without the U). Either way, I apologize in advance for any trans-Atlantic slips; I know how pedantic programmers can be.
Any questions, improvements, suggestions, or debates (I love how opinionated the Go community—as well as the core team and the language itself—is) are more than welcome. These should probably take place in the GitHub issues for the book setup, specifically at https://github.com/matryer/goblueprints, so that everybody can take part.
Finally, I would be thrilled if somebody forms a start-up based on any of these projects, or makes use of them in other places. I would love to hear about it; you can tweet me at @matryer.
Chapter 1, Chat Application with Web Sockets, shows how to build a complete web application that allows multiple people to have a real-time conversation right in their web browser. We will see how the NET/HTTP package let us serve HTML pages as well as connect to the client's browser with web sockets.
Chapter 2, Adding User Accounts, shows how to add OAuth to our chat application so that we can keep track of who is saying what, but let them log in using Google, Facebook, or GitHub.
Chapter 3, Three Ways to Implement Profile Pictures, explains how to add profile pictures to the chat application taken from either the authentication service, the Gravitar.com web service, or by allowing users to upload their own picture from their hard drive.
Chapter 4, Command-Line Tools to Find Domain Names, explores how easy building command-line tools is in Go and puts those skills to use to tackle the problem of finding the perfect domain name for our chat application. It also explores how easy Go makes it to utilize the standard-in and standard-out pipes to produce some pretty powerful composable tools.
Chapter 5, Building Distributed Systems and Working with Flexible Data, explains how to prepare for the future of democracy by building a highly-scalable Twitter polling and vote counting engine powered by NSQ and MongoDB.
Chapter 6, Exposing Data and Functionality through a RESTful Data Web Service API, looks at how to expose the capabilities we built in Chapter 5, Building Distributed Systems and Working with Flexible Data, through a JSON web service, specifically how the wrapping http.HandlerFunc functions give us a powerful pipeline pattern.
Chapter 7, Random Recommendations Web Service, shows how to consume the Google Places API to generate a location-based random recommendations API that represents a fun way to explore any area. It also explores why it's important to keep internal data structures private, controlling the public view into the same data, as well as how to implement enumerators in Go.
Chapter 8, Filesystem Backup, helps to build a simple but powerful filesystem backup tool for our code projects and explore interacting with the filesystem using the OS package from the Go standard library. It also looks at how Go's interfaces allow simple abstractions to yield powerful results.
Chapter 9, Building a Q&A Application for Google App Engine, shows how to build applications that can be deployed to Google's infrastructure and run at high scale with little to no operational duties for us. The project we build utilizes some of the cloud services available on Google App Engine, including the Google Cloud Datastore—a highly available and extremely fast schema-less data storage option.
Chapter 10, Micro-services in Go with the Go Kit Framework, explores a modern software architecture paradigm whereby large monolithic applications are broken down into discrete services with a singular focus. The services run independently of each other, allowing them to be individually scaled to meet demand. Go Kit is a software framework that addresses some of the challenges of a microservice architecture while remaining agnostic to the implementation details.
Chapter 11, Deploying Go Applications Using Docker, looks at how simple it is to build Docker images to package and deploy the application we built in Chapter 9, Building a Q&A Application for Google App Engine. We will write a Dockerfile that describes the image, and use the Docker tools to build the image, which we will then deploy to the Digital Ocean cloud.
Appendix, Good Practices for a Stable Go Environment, shows how to install Go from scratch on a new machine and discusses some of the environmental options we have and the impact they might have in the future. We will look at a few code editor (or IDE—Integrated Developer Environment) options and also consider how collaboration might influence some of our decisions as well as the impact open sourcing our packages might have.
To compile and run the code from this book, you will need a computer capable of running an operating system that supports the Go toolset, a list of which can be found at https://golang.org/doc/install#requirements.
Appendix, Good Practices for a Stable Go Environment, has some useful tips to install Go and set up your development environment, including how to work with the GOPATH environment variable.
This book is for all Go programmers, ranging from beginners looking to explore the language by building real projects to expert gophers with an interest in how the language can be applied in interesting ways.
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "You will notice that the deployable artifact for your application is the webApp.war file."
A block of code is set as follows:
package meander type Cost int8 const ( _ Cost = iota Cost1 Cost2 Cost3 Cost4 Cost5 )
Any command-line input or output is written as follows:
go build -o project && ./project
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Once you install Xcode, you open Preferences and navigate to the Downloads section"
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