Alex Edwards - Lets Go Further

In this book were going to work through the start-to-finish build of an application called Greenlight a JSON API for retrieving and managing information about movies. You can think of the core functionality as being a bit like the Open Movie Database API.

Ultimately, our Greenlight API will support the following endpoints and actions:

Method	URL Pattern	Action
GET	/v1/healthcheck	Show application health and version information
GET	/v1/movies	Show the details of all movies
POST	/v1/movies	Create a new movie
GET	/v1/movies/:id	Show the details of a specific movie
PATCH	/v1/movies/:id	Update the details of a specific movie
DELETE	/v1/movies/:id	Delete a specific movie
POST	/v1/users	Register a new user
PUT	/v1/users/activated	Activate a specific user
PUT	/v1/users/password	Update the password for a specific user
POST	/v1/tokens/authentication	Generate a new authentication token
POST	/v1/tokens/password-reset	Generate a new password-reset token
GET	/debug/vars	Display application metrics

To give you an idea of what the API will look like from a clients point of view, by the end of this book the GET /v1/movies/:id endpoint will return a response similar this:

$ curl -H "Authorization: Bearer RIDBIAE3AMMK57T6IAEBUGA7ZQ" localhost:4000/v1/movies/1{ "movie": { "id": 1, "title": "Moana", "year": 2016, "runtime": "107 mins", "genres": [ "animation", "adventure" ], "version": 1 }}

Behind the scenes, well use PostgreSQL as the database for persistently storing all the data. And at the end of the book, well deploy the finished API to a Linux server running on Digital Ocean.

In this book, code blocks are shown with a silver background like the snippet below. If the code block is particularly long, parts that arent relevant may be replaced with an ellipsis. To make it easy to follow along, most code blocks also have a title bar at the top indicating the name of the file that were working on.

File: hello.go package main ... // Indicates that some existing code has been omitted. func sayHello ( ) { fmt . Println ( "Hello world!" ) }

Terminal (command line) instructions are shown with a black background and generally start with a dollar symbol. These commands should work on any Unix-based operating system, including macOS and Linux. Sample output is shown in silver beneath the command, like so:

$ echo "Hello world!"Hello world!

If youre using Windows, you should replace these commands with the DOS equivalent or carry out the action via the normal Windows GUI.

Some chapters in this book end with an additional information section. These sections contain information that isnt relevant to our application build, but is still important (or sometimes, just interesting) to know about.

Hey, Im Alex Edwards, a full-stack web developer and author. I began working with Go in 2013, and have been teaching people and writing about the language for nearly as long.

Ive used Go to build a variety of production applications, from simple websites to high-frequency trading systems. I also maintain several open-source Go packages, including the popular session management system SCS.

I live near Innsbruck, Austria. You can follow me on GitHub, Instagram, Twitter and on my blog.

Lets Go Further. Copyright 2021 Alex Edwards.

Last updated 2021-05-04 16:59:42 UTC. Version 1.0.0.

The Go gopher was designed by Renee French and is used under the Creative Commons 3.0 Attributions license. Cover gopher adapted from vectors by Egon Elbre.

The information provided within this book is for general informational purposes only. While the author and publisher have made every effort to ensure that the accuracy of the information within this book was correct at time of publication there are no representations or warranties, express or implied, about the completeness, accuracy, reliability, suitability or availability with respect to the information, products, services, or related graphics contained in this book for any purpose. Any use of this information is at your own risk.

This book is written as a follow up to Lets Go, and well leverage a lot of the information and code patterns from that book again here.

If youve already read and enjoyed Lets Go, then this book should be a good fit for you and the ideal next step in your learning. If you havent, then I highly recommend starting with Lets Go first especially if youre a newcomer to Go.

You can read this as a standalone book, but please be aware that it is somewhat advanced it doesnt explain the fundamentals in detail, and some topics (like testing) dont feature at all because they were covered heavily in the previous book. But if youre comfortable using Go and already have a decent amount of experience behind you, then this book may also be a good fit for you. Feel free to jump straight in.

The information in this book is correct for the latest major release of Go (version 1.16), and you should install this if youd like to code-along with the application build.

If youve already got Go installed, you can check the version number from your terminal by using the go version command. The output should look similar to this:

$ go versiongo version go1.16 linux/amd64

If you need to upgrade your version of Go, then please go ahead and do that now. The instructions for your operating system can be found here.

There are a few other bits of software that you should make sure are available on your computer if you want to follow along fully. They are:

• The curl tool for working with HTTP requests and responses from your terminal. On MacOS and Linux machines it should be pre-installed or available in your software repositories. Otherwise, you can download the latest version from here.

• The hey tool for carrying out some basic load tests. If you have Go 1.16 on your computer, you can install hey with the go install command:

  $ go install github.com/rakyll/hey@latest

• The git version control system. Installation instructions for all operating systems can be found here.

• A web browser with good developer tools. Ill be using Firefox in this book, but Chromium, Chrome or Microsoft Edge will work too.

• Your favorite text editor

In this first section of the book, were going to set up a project directory and lay the groundwork for building our Greenlight API. We will:

• Create a skeleton directory structure for the project and explain at a high-level how our Go code and other assets will be organized.

• Establish a HTTP server to listen for incoming HTTP requests.

• Introduce a sensible pattern for managing configuration settings (via command-line flags) and using