Go Programming Cookbook: Over 85 recipes to build modular, readable, and testable Golang applications across various domains. 2 Ed

 Cover....1

Title Page....2

Copyright and Credits....3

Dedication....4

About Packt....5

Contributors....6

Table of Contents....8

Preface....16

Chapter 1: I/O and Filesystems....22

Technical requirements....23

Using the common I/O interfaces....23

How to do it.......24

How it works.......27

Using the bytes and strings packages....27

How to do it.......28

How it works.......32

Working with directories and files....32

How to do it.......32

How it works.......36

Working with the CSV format....37

How to do it.......37

How it works.......42

Working with temporary files....42

How to do it.......43

How it works.......45

Working with text/template and html/template....45

How to do it.......45

How it works.......52

Chapter 2: Command-Line Tools....53

Technical requirements....54

Using command-line flags....54

How to do it.......54

How it works.......58

Using command-line arguments....58

How to do it.......59

How it works.......62

Reading and setting environment variables....63

How to do it.......63

How it works.......67

Configuration using TOML, YAML, and JSON....67

How to do it.......68

How it works.......74

Working with Unix pipes....74

How to do it.......75

How it works.......77

Catching and handling signals....77

How to do it.......77

How it works.......80

An ANSI coloring application....80

How to do it.......80

How it works.......83

Chapter 3: Data Conversion and Composition....84

Technical requirements....84

Converting data types and interface casting....85

How to do it.......85

How it works.......89

Working with numeric data types using math and math/big....89

How to do it.......89

How it works.......93

Currency conversions and float64 considerations....93

How to do it.......93

How it works.......97

Using pointers and SQL NullTypes for encoding and decoding....97

How to do it.......98

How it works.......103

Encoding and decoding Go data....103

How to do it.......103

How it works.......107

Structure tags and basic reflection in Go....108

How to do it.......108

How it works.......113

Implementing collections via closures....114

How to do it.......114

How it works.......118

Chapter 4: Error Handling in Go....119

Technical requirements....119

Handling errors and the Error interface....120

How to do it.......120

How it works.......123

Using the pkg/errors package and wrapping errors....123

How to do it.......124

How it works.......127

Using the log package and understanding when to log errors....127

How to do it.......128

How it works.......130

Structured logging with the apex and logrus packages....131

How to do it.......131

How it works.......135

Logging with the context package....135

How to do it.......135

How it works.......138

Using package-level global variables....139

How to do it.......139

How it works.......142

Catching panics for long-running processes....142

How to do it.......142

How it works.......144

Chapter 5: Network Programming....145

Technical requirements....145

Writing a TCP/IP echo server and client....146

How to do it.......146

How it works.......149

Writing a UDP server and client....150

How to do it.......150

How it works.......154

Working with domain name resolution....154

How to do it.......155

How it works.......157

Working with WebSockets....157

How to do it.......158

How it works.......162

Working with net/rpc for calling remote methods....163

How to do it.......163

How it works.......166

Using net/mail for parsing emails....167

How to do it.......167

How it works.......169

Chapter 6: All about Databases and Storage....170

Using the database/sql package with MySQL....170

Getting ready....171

How to do it.......171

How it works.......175

Executing a database transaction interface....176

Getting ready....176

How to do it.......176

How it works.......180

Connection pooling, rate limiting, and timeouts for SQL....180

Getting ready....180

How to do it.......181

How it works.......183

Working with Redis....184

Getting ready....184

How to do it.......184

How it works.......188

Using NoSQL with MongoDB....188

Getting ready....189

How to do it.......189

How it works.......192

Creating storage interfaces for data portability....192

Getting ready....193

How to do it.......193

How it works.......197

Chapter 7: Web Clients and APIs....198

Technical requirements....198

Initializing, storing, and passing http.Client structures....199

How to do it.......199

How it works.......203

Writing a client for a REST API....203

How to do it.......204

How it works.......207

Executing parallel and async client requests....207

How to do it.......207

How it works.......210

Making use of OAuth2 clients....210

Getting ready....211

How to do it.......211

How it works.......214

Implementing an OAuth2 token storage interface....214

Getting ready....215

How to do it.......215

How it works.......220

Wrapping a client in added functionality and function composition....221

How to do it.......222

How it works.......225

Understanding GRPC clients....226

Getting ready....226

How to do it.......226

How it works.......230

Using twitchtv/twirp for RPC....230

Getting ready....231

How to do it.......231

How it works.......235

Chapter 8: Microservices for Applications in Go....236

Technical requirements....237

Working with web handlers, requests, and ResponseWriter instances....237

How to do it.......238

How it works.......241

Using structures and closures for stateful handlers....241

How to do it.......242

How it works.......246

Validating input for Go structures and user inputs....246

How to do it.......246

How it works.......250

Rendering and content negotiation....251

How to do it.......251

How it works.......254

Implementing and using middleware....254

How to do it.......255

How it works.......259

Building a reverse proxy application....259

How to do it.......259

How it works.......263

Exporting GRPC as a JSON API....263

Getting ready....263

How to do it.......264

How it works.......270

Chapter 9: Testing Go Code....271

Technical requirements....271

Mocking using the standard library....272

How to do it.......272

How it works.......276

Using the Mockgen package to mock interfaces....276

Getting ready....277

How to do it.......277

How it works.......280

Using table-driven tests to improve coverage....281

How to do it.......281

How it works.......283

Using third-party testing tools....284

Getting ready....284

How to do it.......284

How it works.......288

Behavior testing using Go....289

Getting ready....289

How to do it.......290

How it works.......293

Chapter 10: Parallelism and Concurrency....295

Technical requirements....296

Using channels and the select statement....296

How to do it.......296

How it works.......299

Performing async operations with sync.WaitGroup....300

How to do it.......300

How it works.......304

Using atomic operations and mutex....304

How to do it.......305

How it works.......308

Using the context package....309

How to do it.......309

How it works.......312

Executing state management for channels....312

How to do it.......313

How it works.......316

Using the worker pool design pattern....317

How to do it.......317

How it works.......322

Using workers to create pipelines....322

How to do it.......322

How it works.......327

Chapter 11: Distributed Systems....328

Technical requirements....328

Using service discovery with Consul....329

How to do it.......329

How it works.......332

Implementing basic consensus using Raft....333

How to do it.......333

How it works.......340

Using containerization with Docker....341

Getting ready....341

How to do it.......341

How it works.......345

Orchestration and deployment strategies....345

How to do it.......346

How it works.......349

Monitoring applications....349

How to do it.......349

How it works.......353

Collecting metrics....353

Getting ready....354

How to do it.......354

How it works.......357

Chapter 12: Reactive Programming and Data Streams....358

Technical requirements....358

Using Goflow for data flow programming....359

How to do it.......359

How it works.......362

Using Kafka with Sarama....363

Getting ready....363

How to do it.......363

How it works.......366

Using async producers with Kafka....366

Getting ready....367

How to do it.......367

How it works.......370

Connecting Kafka to Goflow....370

Getting ready....371

How to do it.......371

How it works.......374

Writing a GraphQL server in Go....375

How to do it.......375

How it works.......381

Chapter 13: Serverless Programming....382

Go programming on Lambda with Apex....382

Getting ready....383

How to do it.......383

How it works.......387

Apex serverless logging and metrics....387

Getting ready....388

How to do it.......388

How it works.......391

Google App Engine with Go....391

Getting ready....392

How to do it.......392

How it works.......396

Working with Firebase using firebase.google.com/go....397

Getting ready....397

How to do it.......398

How it works.......401

Chapter 14: Performance Improvements, Tips, and Tricks....402

Technical requirements....402

Using the pprof tool....403

How to do it.......403

How it works.......407

Benchmarking and finding bottlenecks....408

How to do it.......408

How it works.......412

Memory allocation and heap management....412

How to do it.......412

How it works.......415

Using fasthttprouter and fasthttp....416

How to do it.......416

How it works.......419

Other Books You May Enjoy....420

Index....423

Go (or Golang) is a statically typed programming language developed at Google. Known for its vast standard library, it also provides features such as garbage collection, type safety, dynamic-typing capabilities, and additional built-in types. This book will serve as a reference while implementing Go features to build your own applications.

This Go cookbook helps you put into practice the advanced concepts and libraries that Golang offers. The recipes in the book follow best practices such as documentation, testing, and vendoring with Go modules, as well as performing clean abstractions using interfaces. You'll learn how code works and the common pitfalls to watch out for. The book covers basic type and error handling, and then moves on to explore applications, such as websites, command-line tools, and filesystems, that interact with users. You'll even get to grips with parallelism, distributed systems, and performance tuning.

By the end of the book, you'll be able to use open source code and concepts in Go programming to build enterprise-class applications without any hassle.

What you will learn

• Work with third-party Go projects and modify them for your use
• Write Go code using modern best practices
• Manage your dependencies with the new Go module system
• Solve common problems encountered when dealing with backend systems or DevOps
• Explore the Go standard library and its uses
• Test, profile, and fine-tune Go applications

Who this book is for

If you're a web developer, programmer, or enterprise developer looking for quick solutions to common and not-so-common problems in Go programming, this book is for you. Basic knowledge of the Go language is assumed.