9. Building a Q&A Application for Google App Engine | .Go Programming Blueprints

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.Go Programming Blueprints - Second Edition

By : Mat Ryer

3.9 (12)

.Go Programming Blueprints

3.9 (12)

By: Mat Ryer

Overview of this book

Go is the language of the Internet age, and the latest version of Go comes with major architectural changes. Implementation of the language, runtime, and libraries has changed significantly. The compiler and runtime are now written entirely in Go. The garbage collector is now concurrent and provides dramatically lower pause times by running in parallel with other Go routines when possible. This book will show you how to leverage all the latest features and much more. This book shows you how to build powerful systems and drops you into real-world situations. You will learn to develop high quality command-line tools that utilize the powerful shell capabilities and perform well using Go's in-built concurrency mechanisms. Scale, performance, and high availability lie at the heart of our projects, and the lessons learned throughout this book will arm you with everything you need to build world-class solutions. You will get a feel for app deployment using Docker and Google App Engine. Each project could form the basis of a start-up, which means they are directly applicable to modern software markets.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Chat Application with Web Sockets

1. Chat Application with Web Sockets

A simple web server

Modeling a chat room and clients on the server

Building an HTML and JavaScript chat client

Tracing code to get a look under the hood

Summary

2. Adding User Accounts

2. Adding User Accounts

Handlers all the way down

Making a pretty social sign-in page

Endpoints with dynamic paths

Getting started with OAuth2

Tell the authorization providers about your app

Implementing external logging in

Summary

3. Three Ways to Implement Profile Pictures

3. Three Ways to Implement Profile Pictures

Avatars from the OAuth2 server

Implementing Gravatar

Uploading an avatar picture

Combining all three implementations

Summary

4. Command-Line Tools to Find Domain Names

4. Command-Line Tools to Find Domain Names

Pipe design for command-line tools

Five simple programs

Composing all five programs

Summary

5. Building Distributed Systems and Working with Flexible Data

5. Building Distributed Systems and Working with Flexible Data

The system design

Installing the environment

Reading votes from Twitter

Counting votes

Running our solution

Summary

6. Exposing Data and Functionality through a RESTful Data Web Service API

6. Exposing Data and Functionality through a RESTful Data Web Service API

RESTful API design

Sharing data between handlers

Wrapping handler functions

Injecting dependencies

Responding

Understanding the request

Serving our API with one function

Handling endpoints

A web client that consumes the API

Running the solution

Summary

7. Random Recommendations Web Service

7. Random Recommendations Web Service

The project overview

Representing data in code

Generating random recommendations

Summary

8. Filesystem Backup

8. Filesystem Backup

Solution design

The backup package

The user command-line tool

The daemon backup tool

Testing our solution

Summary

9. Building a Q&A Application for Google App Engine

9. Building a Q&A Application for Google App Engine

The Google App Engine SDK for Go

Google Cloud Datastore

Entities and data access

Google App Engine users

Transactions in Google Cloud Datastore

Querying in Google Cloud Datastore

Votes

Casting a vote

Exposing data operations over HTTP

Running apps with multiple modules

Deploying apps with multiple modules

Summary

10. Micro-services in Go with the Go kit Framework

10. Micro-services in Go with the Go kit Framework

Introducing gRPC

Protocol buffers

Building the service

Modeling method calls with requests and responses

An HTTP server in Go kit

A gRPC server in Go kit

Creating a server command

Building a gRPC client

Rate limiting with service middleware

Summary

11. Deploying Go Applications Using Docker

11. Deploying Go Applications Using Docker

Using Docker locally

Deploying Docker images

Deploying to Digital Ocean

Summary

Appendix. Good Practices for a Stable Go Environment

Appendix. Good Practices for a Stable Go Environment

Installing Go

Configuring Go

Go tools

Cleaning up, building, and running tests on save

Integrated developer environments

Summary

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Google App Engine users

Another service we are going to make use of is the Google App Engine Users API, which provides the authentication of Google accounts (and Google Apps accounts).

Create a new file called users.go and add the following code:

type User struct { 
  Key *datastore.Key `json:"id" datastore:"-"` 
  UserID string `json:"-"` 
  DisplayName string `json:"display_name"` 
  AvatarURL string `json:"avatar_url"` 
  Score int `json:"score"` 
}

Similar to the Question struct, we have Key and a few fields that make up the User entity. This struct represents an object that belongs to our application that describes a user; we will have one for every authenticated user in our system, but this isn't the same user object that we'll get from the Users API.

Importing the https://godoc.org/google.golang.org/appengine/user package and calling the user.Current(context.Context) function will return either nil (if no user is authenticated) or a user.User object. This object belongs to the Users...

Visually different images

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