Practical Go

Оглавление

Amit Saha. Practical Go

Table of Contents

List of Tables

List of Illustrations

Guide

Pages

Practical Go. Building Scalable Network and Non-Network Applications

Introduction

What Does This Book Cover?

Reader Support for This Book

Getting Started

Installing Go

Choosing an Editor

Installing Protocol Buffer Toolchain

Linux and macOS

Windows

Installing Docker Desktop

Guide to the Book

Go Modules

Command Line and Terminals

Terms

Robustness and Resiliency

Production Readiness

Reference Documentation

Go Refresher

Struct Type

Interface Type

Goroutines and Channels

Testing

Summary

CHAPTER 1 Writing Command-Line Applications

Your First Application

Listing 1.1: A greeter application

Writing Unit Tests

Listing 1.2: Test for the parseArgs() function

Listing 1.3: Test for the validateArgs() function

Listing 1.4: Test for the runCmd() function

Using the Flag Package

Listing 1.5: Greeter using flag

Testing the Parsing Logic

Listing 1.6: Test for the parseArgs() function

Improving the User Interface

Removing Duplicate Error Messages

Customizing Usage Message

Accept Name via a Positional Argument

Listing 1.7: Greeter program with user interface updates

Updating the Unit Tests

Listing 1.8: Test for parseArgs() function

Listing 1.9: Test for runCmd() function

Summary

CHAPTER 2 Advanced Command-Line Applications

Implementing Sub-commands

Listing 2.1: Implementing sub-commands in a command-line application

An Architecture for Sub-command-Driven Applications

Listing 2.2: Implementation of the main package

Listing 2.3: Implementation of the HandleHttp() function

Listing 2.4: Implementation of the HandleGrpc() function

Listing 2.5: Custom error values

Testing the Main Package

Listing 2.6: Unit test for the main package

Testing the Cmd Package

Making Your Applications Robust

User Input with Deadlines

Listing 2.7: Implementing time-out for user input

Handling User Signals

Listing 2.8: Handling user signals

Summary

CHAPTER 3 Writing HTTP Clients

Downloading Data

Listing 3.1: A basic data downloader

Testing the Data Downloader

Listing 3.2: Test for fetchRemoteResource() function

Deserializing Received Data

Listing 3.3: Querying data from the package server

Listing 3.4: Test for pkgquery

Sending Data

Listing 3.5: Register a new package

Listing 3.6: Test for registering a new package

Working with Binary Data

Listing 3.7: Creating a multipart message

Listing 3.8: Package registration using multipart message

Listing 3.9: Test for package registration with multipart message

Summary

CHAPTER 4 Advanced HTTP Clients

Using a Custom HTTP Client

Downloading from an Overloaded Server

Listing 4.1: Test for fetchRemoteResource() function with a bad server

Listing 4.2: The data downloader application with a custom HTTP client with time-out

Testing the Time-Out Behavior

Listing 4.3: Test for fetchRemoteResource() function with a bad server

Listing 4.4: Test for fetchRemoteResource() function with the updated bad server

Configuring the Redirect Behavior

Listing 4.5: A data downloader that exits if there is a redirect attempt

Customizing Your Requests

Implementing Client Middleware

Understanding the RoundTripper Interface

A Logging Middleware

Listing 4.6: A data downloader with a custom logging middleware

Add a Header to All Requests

Listing 4.7: An HTTP client with a middleware to add custom headers

Listing 4.8: Test for middleware to add headers

Connection Pooling

Listing 4.9: A program to illustrate connection pooling

Configuring the Connection Pool

Summary

CHAPTER 5 Building HTTP Servers

Your First HTTP Server

Listing 5.1: A basic HTTP server

Setting Up Request Handlers

Handler Functions

Listing 5.2: An HTTP server using a dedicated ServeMux object

Testing Your Server

Listing 5.3: A test for the HTTP server

The Request Struct

Method

URL

Proto, ProtoMajor, and ProtoMinor

Header

Host

Body

Form, PostForm

MultipartForm

Attaching Metadata to a Request

Listing 5.4: Attaching metadata to a request

Processing Streaming Requests

Listing 5.5: Decoding JSON data using Decode()

Streaming Data as Responses

Listing 5.6: Streaming response

Summary

CHAPTER 6 Advanced HTTP Server Applications

The Handler Type

Sharing Data across Handler Functions

Listing 6.1: An HTTP server using a custom handler type

Writing Server Middleware

Custom HTTP Handler Technique

The HandlerFunc Technique

Chaining Middleware

Listing 6.2: Chaining middleware using http.HandleFunc

Writing Tests for Complex Server Applications

Code Organization

Listing 6.3: Managing application configuration

Listing 6.4: Request handlers

Listing 6.5: Setting up the request handlers

Listing 6.6: Logging and panic-handling middleware

Listing 6.7: Middleware registration

Listing 6.8: Main server

Testing the Handler Functions

Listing 6.9: Test for the API handler function

Testing the Middleware

Listing 6.10: Test for panic-handling middleware

Testing the Server Startup

Listing 6.11: Test for server setup

Summary

CHAPTER 7 Production-Ready HTTP Servers

Aborting Request Handling

Listing 7.1: Enforcing time-out on a handler function

Strategies to Abort Request Processing

Listing 7.2: Enforcing time-out on a handler function

Handling Client Disconnects

Listing 7.3: Handling client disconnects

Server-Wide Time-Outs

Implement a Time-Out for All Handler Functions

Implementing Server Time-Out

Listing 7.4: Configuring server time-outs

Implementing Graceful Shutdown

Listing 7.5: Implementing graceful shutdown in a server

Securing Communication with TLS

Configuring TLS and HTTP/2

Listing 7.6: Securing an HTTP server using TLS

Testing TLS Servers

Listing 7.7: Securing an HTTP server using TLS with a configurable logger

Listing 7.8: Verify middleware behavior in a TLS-enabled HTTP server

Summary

CHAPTER 8 Building RPC Applications with gRPC

gRPC and Protocol Buffers

Writing Your First Service

Listing 8.1: Protobuf specification for Users service

Writing the Server

Listing 8.2: gRPC server for the Users service

Listing 8.3: go.mod file for the Users gRPC server

Writing a Client

Listing 8.4: Client for the Users service

Listing 8.5: go.mod file for the Users service client

Testing the Server

Listing 8.6: Test for the Users service

Testing the Client

Listing 8.7: Test for the Users service client

A Detour into Protobuf Messages

Marshalling and Unmarshalling

Listing 8.8: Client for the Users service

Listing 8.9: go.mod file for the Users service client supporting a JSON-formatted query

Listing 8.10: Client for the Users service working with JSON and protobuf

Forward and Backward Compatibility

Multiple Services

Listing 8.11: Protobuf specification for the Repo service

Listing 8.12: gRPC Server with both the Users and Repo services

Listing 8.13: go.mod file for gRPC service with the User and Repo services

Error Handling

Summary

CHAPTER 9 Advanced gRPC Applications

Streaming Communication

Server-Side Streaming

Listing 9.1: Protobuf specification for the Repo service

Listing 9.2: gRPC server for Users and Repo service

Listing 9.3: go.mod file for the server

Listing 9.4: Test function for the Repo service

Client-Side Streaming

Bidirectional Streaming

Listing 9.5: Protobuf specification for the Users service

Listing 9.6: Server for the Users service

Listing 9.7: go.mod file for the server

Listing 9.8: Client for the Users service

Listing 9.9: go.mod file for the client

Receiving and Sending Arbitrary Bytes

Listing 9.10: Protobuf specification for the Repo service

Listing 9.11: Server for the Repo service

Listing 9.12: go.mod file for the Repo service server implementation

Implementing Middleware Using Interceptors

Listing 9.13: go.mod file for the Users service

Listing 9.14: go.mod file for the Users server

Listing 9.15: go.mod file for the Users client

Client-Side Interceptors

Listing 9.16: Updated protobuf specification for the Users service

Listing 9.17: Client application for the Users service with interceptors

Server-Side Interceptors

Listing 9.18: Server application for the Users service with interceptors

Wrapping Streams

Chaining Interceptors

Summary

CHAPTER 10 Production-Ready gRPC Applications

Securing Communication with TLS

Robustness in Servers

Implementing Health Checks

Handling Runtime Errors

Aborting Request Processing

Robustness in Clients

Improving Connection Setup

Handling Transient Failures

Setting Time-Outs for Method Calls

Connection Management

Summary

CHAPTER 11 Working with Data Stores

Working with Object Stores

Integration with Package Server

Testing Package Uploads

Accessing Underlying Driver Types

Working with Relational Databases

Integration with Package Server

Testing Data Storage

Data Type Conversions

Using Database Transactions

Summary

APPENDIX A Making Your Applications Observable

Logs, Metrics, and Traces

Emitting Telemetry Data

Command-Line Applications

HTTP Applications

gRPC Applications

Summary

APPENDIX B Deploying Applications

Managing Configuration

Distributing Your Application

Deploying Server Applications

Summary

Index

About the Author

About the Technical Editor

Acknowledgments

WILEY END USER LICENSE AGREEMENT

Отрывок из книги

NOTE A glossary of relevant terms is available for free download from the book's web page: https://www.wiley.com/go/practicalgo.

My goal in this book is to showcase the various features of the Go language and the standard libraries (along with a few community-maintained packages) by developing various categories of applications. Once you have refreshed or learned the language fundamentals, this book will help you take the next step. I have adopted a writing style where the focus is on using various features of the language and its libraries to solve the particular problem at hand—one that you care about.

.....

The function takes two parameters: a variable, w, whose value satisfies the io.Writer interface, and an array of strings representing the arguments to parse. It returns a config object and an error value. To parse the arguments, a new FlagSet object is created as follows:

fs := flag.NewFlagSet("greeter", flag.ContinueOnError)

.....