Hands-On Microservices with JavaScript: Build scalable web applications with JavaScript, Node.js, and Docker

Hands-On Microservices with JavaScript

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To Elvira, my steadfast companion, whose unwavering love and support has been the bedrock of my life and work. To Turgut and Farah, my beloved children, whose existence fills my world with immeasurable joy and purpose.

Every challenge I’ve faced has been a crucible, forging the strength and resilience necessary for this journey. I am eternally grateful for the trials that have shaped me, and for the love that has carried me through.

– Tural Suleymani

Contributors

About the author

Tural Suleymani is a seasoned software development expert with over a decade of industry experience. Renowned as Azerbaijan’s first Microsoft MVP in .NET and a three-time C# Corner MVP, he has established himself as a leading authority in his field. With a passion for sharing knowledge, Tural has dedicated ten years to mentoring developers through comprehensive programming languages and technology tools instruction. A self-taught pioneer, he empowers a global audience through his TuralSuleymaniTech YouTube channel, where he delivers in-depth tutorials and insights on C#, Apache Kafka, SQL, JavaScript, Domain-Driven Design, software architecture, microservices, and more. His deep technical knowledge and practical insights have empowered countless developers through his work as a mentor, educator, and public speaker. He also holds prestigious certifications including MCP, MCSA, and MSCD from Microsoft. Tural is also a Udemy instructor, further expanding his educational reach. Currently, Tural holds the position of Chief Software Architect at VOE Consulting, where he continues to innovate and lead in the software development industry.

About the reviewer(s)

Rasul Huseynov is a senior software developer and consultant with over seven years of experience in delivering high-quality software solutions. He graduated with high honors in computer engineering and brings deep expertise in Object-Oriented Analysis and Design (OOAD), Extreme Programming, and Distributed Systems. Holding certifications such as MCP, MCSA, and MCSD, Rasul has a solid foundation in Microsoft technologies and has successfully delivered numerous web projects. His experience extends to ensuring that software solutions are robust, maintainable, and efficient while adhering to industry best practices.

Adewole Caleb is a skilled backend engineer with a solid foundation in JavaScript, Golang, and TypeScript. Over his five years of professional experience, he has built a reputation for his curiosity, problem-solving abilities, and dedication to continuous learning. Having recently graduated, Caleb is now exploring a career transition into distributed and system engineering. Beyond his professional work, Caleb is deeply passionate about music. He finds joy in playing the guitar, singing, and participating in other activities that allow him to express his creativity. Caleb volunteers as a boot camp tutor, where he shares his knowledge and experience to inspire budding developers.

Joel Edmond Nguemeta is a full-stack developer and mentor with expertise in web application development and system design. He has worked as a mentor and evaluator at OpenClassrooms, providing personalized support to numerous students and contributing to their professional growth. As a mobile developer at Tamangwa Shipping, he designed several custom systems tailored to the company’s specific needs. Joel also has solid experience in creating and implementing microservices architectures, ensuring scalability and performance. He regularly shares his knowledge and technical advice on his YouTube channel, which is dedicated to the developer community.

Jean Clayton Seraphin is an accomplished full-stack developer with over five years of experience in the industry. He has honed his skills in building robust APIs using Python and Django, as well as crafting engaging frontend applications with ReactJS. Beyond his expertise in web development, Jean Clayton Seraphin boasts an advanced understanding of servers and cloud services, particularly in the realm of AWS. He is well-versed in Linux administration and proficient in utilizing infrastructure-as-code tools such as Docker, CircleCI, and Nginx to streamline deployment and ensure the scalability and reliability of his projects.

Table of Contents

Preface

Part 1: Fundamentals of Microservices Architecture

1

Introduction to Microservices

Introducing microservices

Moving toward microservices

Understanding a big ball of mud

Understanding the software development process

Exploring the monolith approach

What is service-oriented architecture?

The differences between SOA and microservices

Advantages of microservices

Disadvantages of microservices

Summary

2

Diving into Microservices Internals

Solidifying the communication

Microservice communication techniques

Introduction to APIs

What exactly is REST?

HTTP-based REST implementation

HTTP response status codes

Introduction to GraphQL

Remote Procedure Call

Synchronous microservice communication

Asynchronous microservice communication

Essential communication patterns

Message brokers

Summary

3

What Do You Need Before Getting Started?

Technical requirements

JavaScript essentials

JavaScript engine

JavaScript runtime

Callback-based asynchronous JavaScript

The way to promises

Promise API

Async/await in JavaScript

Microtask queue

Node.js essentials

Summary

4

Stack Development Technologies

Technical requirements

Node.js and its installation

Installing Node.js for Windows

Installing Node.js for macOS and Linux

Node.js frameworks

Express.js

NestJS

Choosing between Express.js and Node.js

Choosing the right IDE

Understanding and installing Docker

Understanding and installing Apache Kafka

Understanding and installing Git

Installing Postman

Installing MongoDB

Summary

Part 2: Building and Managing Microservices

5

Basic CRUD Microservices

Technical requirements

Understanding business requirements

Tools to develop a basic microservice

Preparing our first project

Understanding the concept of packages

Understanding the package.json file

Understanding index.js files

Installing the required packages

Defining the internal architecture of our microservice

MVC architectural pattern

Integrating MVC into our Node.js project

Hands-on account microservice development

Implementing our data-access functionalities

Implementing the M in MVC

Storing configuration

Implementing the business layer

Implementing the controller

Simple data validation for your API

Implementing routing

Constructing our web application

Combining all the elements

Running and testing our first microservice

Creating a new account

Getting an account by ID

Updating an account by ID

Gettings all accounts

Deleting account by ID

Summary

6

Synchronous Microservices

Technical requirements

Understanding the requirements for the transaction microservice

Tools to develop the transaction microservice

NestJS

Docker

Prisma ORM

Hands-on transaction microservice development

Dockerizing your PostgreSQL instance

Modeling the data

Seeding test data

Implementing the transaction service

Configuring Swagger

Working on transaction implementation

Establishing synchronous communication with the account microservice

Summary

7

Asynchronous Microservices

Technical requirements

Understanding the requirements

Exploring asynchronous communication

Implementing an asynchronous transaction microservice

Getting started with Kafka for NestJS

Cluster and brokers in Kafka

Topic and partition concepts in Apache Kafka

Configuring Apache Kafka

Adding an asynchronous nature to a transaction microservice

Adapting an account service to new requirements

Testing our microservices together

Summary

8

Real-Time Data Streaming Using Microservices

Technical requirements

What is real-time streaming?

Why real-time data is essential

Understanding use cases

Relationship between real-time streaming and microservices

Microservices we will develop

Getting started with an earthquake streaming API

Implementing the earthquake stream consumer

Summary

Part 3: Securing, Testing, and Deploying Microservices

9

Securing Microservices

Technical requirements

Security, authentication, and authorization in microservices

Understanding security

Exploring authentication

Defining authorization

Best practices for authorization

Difference between authentication and authorization

Getting started with JWTs

Implementing an Authentication microservice

Integrating token-based authentication for the account microservice

Summary

10

Monitoring Microservices

Technical requirements

Importance of observability

Introduction to logging

Logging levels and node libraries

Log formats

Best practices for logging

Implementing logging in your microservices

Centralized logging with Elasticsearch, Logstash, and Kibana (ELK) stack

A brief introduction to Logstash

A brief introduction to Elasticsearch

A brief introduction to Kibana

Summary

11

Microservices Architecture

Technical requirements

Getting started with an API gateway

How an API Gateway works

Single versus multiple API gateways

Implementing microservices using an API gateway

CQRS and event sourcing

Understanding CQRS

Event sourcing

Event store

Implementing CQRS and event sourcing

Commands and handlers

Implementing an aggregate root

Implementing projection

Implementing API functionalities

Testing an application

Service Registry and discovery in microservices

Understanding Service Registry and discovery

Approaches for implementing Service Registry and Discovery

Implementing Service Registry

Summary

12

Testing Microservices

Technical requirements

Understanding testing in a microservice architecture

Understanding unit tests

Introducing unit testing packages

What should we test in unit testing?

Implementing unit tests for the account microservice

Writing unit tests for the transaction microservice

Comparing mocks, stubs, and spies in unit tests

Mocks

Stubs

Spies

Understanding and implementing integration tests

Summary

13

A CI/CD Pipeline for Your Microservices

The essentials of CI/CD processes

Understanding CI

Understanding CD

Integrating CI/CD into microservices

Working with Azure Cloud

Working with GitHub Actions

Understanding Secrets

Building a pipeline

Summary

Index

Other Books You May Enjoy

Preface

Hello there! Welcome to Hands-On Microservices with JavaScript, a journey through the fascinating intersection of one of the most popular programming languages and the ever-evolving world of microservices architecture. JavaScript, with its versatility and ubiquity, combined with the modular, scalable power of microservices, forms the perfect duo for modern software development. This book is designed to bridge these two worlds, offering a comprehensive guide to building, managing, and scaling microservices with JavaScript.

The rise of microservices has revolutionized the way we think about software architecture. Gone are the days when monolithic applications dominated the landscape, offering simplicity but at the cost of scalability and flexibility. Microservices, with their promise of independent, self-contained units, have brought about a new era of development: agile, resilient, and highly scalable. However, with great power comes great responsibility, and the challenges of adopting a microservices architecture should not be underestimated.

In this book, we’ll take you step by step through the process of understanding and implementing microservices using JavaScript. Each chapter is crafted to not only introduce you to the theoretical concepts but also to provide hands-on guidance that you can apply in real-world scenarios.

We will start with an introduction to microservices, exploring their core principles, benefits, and challenges. From there, we will delve into the internals of microservices, focusing on communication techniques and patterns that are essential for building robust systems. We’ll also cover the foundational knowledge you need in JavaScript and Node.js before diving into more advanced topics, such as real-time data streaming, securing your microservices, and deploying them to production.

This book is not just about writing code; it’s also about understanding the architectural patterns and best practices that will allow you to build scalable, maintainable, and efficient microservices. Whether you’re an experienced developer looking to expand your skill set or a newcomer eager to explore the world of microservices, this book is designed to be your guide.

Thank you for embarking on this journey with me. I hope this book will not only enhance your technical skills but also inspire you to push the boundaries of what you can achieve with microservices and JavaScript.

Let’s dive in!

Who this book is for

This book is designed for software developers, architects, and IT professionals who are eager to dive into the world of microservices using JavaScript. Whether you’re new to microservices or looking to enhance your existing knowledge, this book provides practical insights and hands-on experience to help you build, manage, and scale microservices in a real-world context.

You are likely to benefit from this book if you belong to one of the following groups:

JavaScript developers: If you’re a JavaScript developer interested in expanding your skill set into the microservices architecture, this book will guide you through the process. You’ll learn how to apply your existing JavaScript knowledge to build scalable and resilient microservices, gaining insights into best practices, common challenges, and effective solutions.

Software architects: For architects looking to design and implement microservices architectures, this book offers a comprehensive exploration of patterns, tools, and strategies. You’ll learn how to make informed decisions on structuring and deploying microservices, ensuring that your systems are both flexible and robust.

DevOps and IT professionals: If you’re involved in the deployment, monitoring, and maintenance of microservices, this book will equip you with the knowledge to manage these systems effectively. You’ll gain a deep understanding of CI/CD pipelines, containerization, orchestration, and monitoring techniques that are critical for running microservices in production environments.

This book will provide you with the practical knowledge and tools you need to successfully navigate the complexities of microservices architecture with JavaScript, positioning you for success in today’s fast-paced development landscape.

What this book covers

Chapter 1

, Introduction to Microservices, provides an introduction to microservices architecture, exploring its core principles and defining microservices as small, independent units focused on specific functionalities. This chapter also contrasts microservices with traditional monolithic architecture, highlighting the pros and cons of each approach and setting the stage for the rest of the book.

Chapter 2

, Diving into Microservices Internals, delves deeper into the internal workings of microservices. It covers microservice communication techniques, including REST, GraphQL, and Remote Procedure Call (RPC), and explains both synchronous and asynchronous communication methodologies. The chapter also explores popular communication patterns such as API gateways and message queues, providing a theoretical foundation that is essential for practical implementation.

Chapter 3

, What Do You Need Before Getting Started?, focuses on the essential concepts of JavaScript and Node.js that you need to understand before building microservices. This chapter covers JavaScript engine internals, asynchronous programming, the Node.js runtime environment, and the crucial role of threading and runtime management in building effective microservices.

Chapter 4

, Stack Development Technologies, introduces the essential tools and technologies required to develop and manage microservices with JavaScript. This includes a deep dive into Node.js and various frameworks, choosing the right IDE, and the installation and use of Docker and Git. The chapter also covers Postman, a key tool for testing APIs and interacting with microservices during development.

Chapter 5

, Basic CRUD Microservices, takes a practical approach by guiding you through the development of your first microservice using Express.js. This chapter covers the tools required, the internal architecture of microservices, and the step-by-step process of creating and testing a basic CRUD (Create, Read/Retrieve, Update, Delete) microservice, preparing you for more complex implementations.

Chapter 6

, Synchronous Microservices, explores the creation and orchestration of synchronous communication between microservices. This chapter focuses on building a second microservice using NestJS and establishing communication between services.

Chapter 7

, Asynchronous Microservices, delves into the world of asynchronous communication, a crucial aspect of building scalable systems. The chapter covers the implementation of Apache Kafka for asynchronous messaging, setting up the infrastructure for Kafka with NestJS, and building an asynchronous transaction service. It also breaks down Kafka’s core concepts and explains how to incorporate asynchronous communication into your microservices architecture.

Chapter 8

, Real-Time Data Streaming Using Microservices, explores the power of real-time data streaming within a microservices ecosystem. This chapter covers the concept of streaming, its benefits, and how to implement stream processing microservices using Node.js. It also demonstrates how to integrate these services with Apache Kafka to build a real-time data pipeline.

Chapter 9

, Securing Microservices, focuses on the fundamental aspects of securing microservices by implementing robust authentication mechanisms. It covers the use of JSON Web Tokens (JWT) for stateless authentication, discusses centralized and decentralized approaches to security, and demonstrates how to build a dedicated authentication microservice. Additionally, best practices for ensuring your microservices' confidentiality, integrity, and availability are provided, offering a solid foundation for secure microservice architectures.

Chapter 10

, Monitoring Microservices, focuses on equipping your microservices with robust observability and monitoring practices. This chapter covers the importance of logging and monitoring in microservice architectures, ensuring that you can effectively track the health and performance of your system. It introduces essential observability concepts such as logs, metrics, and traces and explores centralized logging with the ELK Stack (Elasticsearch, Logstash, and Kibana). By the end of this chapter, you’ll have a strong foundation for implementing logging and monitoring strategies to keep your microservices resilient and responsive.

Chapter 11

, Microservices Architecture, provides a deep dive into advanced architectural patterns for microservices. This chapter explores the API gateway, event-sourcing, and Command Query Responsibility Segregation (CQRS) patterns to separate reads and writes.

Chapter 12

, Testing Microservices, emphasizes the importance of testing in maintaining microservices’ stability and reliability. This chapter covers essential testing strategies, including unit tests and integration tests, ensuring that your microservices can withstand any demand and work seamlessly together.

Chapter 13

, A CI/CD Pipeline for Your Microservices, unveils the process of automating microservices development through Continuous Integration (CI) and Continuous Delivery (CD). This chapter covers the essentials of CI/CD processes, working with GitHub Actions, building a robust pipeline that streamlines the transition from development to production and deploying your application to Azure Cloud.

To get the most out of this book

To fully benefit from this book, you should have a foundational understanding of JavaScript and basic programming concepts. Familiarity with Node.js, including its runtime environment and asynchronous programming model, will be advantageous as you dive into microservices development. Additionally, a basic knowledge of web development and RESTful APIs will help you grasp the communication techniques and patterns discussed in the book. While not mandatory, experience with Docker, Git, and CI/CD processes will enhance your ability to follow along with the practical examples and deployment strategies covered in the later chapters.

While the aforementioned versions are specific to Windows, Node.js, Docker Desktop, Visual Studio Code, and Postman also work seamlessly on macOS and Linux. Users of these operating systems should download their appropriate versions from the official websites. The core functionality remains consistent across all operating systems, ensuring a similar experience regardless of your platform.

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For your convenience, you can download the source code to follow along with the book. However, most chapters also provide detailed instructions to guide you in writing everything from scratch, ensuring that you understand each step of the process.

Download the example code files

You can download the example code files for this book from GitHub at https://github.com/PacktPublishing/Hands-on-Microservices-with-JavaScript

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We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/

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Part 1:Fundamentals of Microservices Architecture

In this part, we will gain a comprehensive understanding of the foundational principles and internal workings of microservices architecture. We will explore what microservices are, how they compare to traditional monolithic architectures, and the various communication techniques and patterns that make microservices a robust and scalable solution. Additionally, we’ll learn the essential JavaScript and Node.js concepts that are necessary to develop microservices.

This part contains the following chapters:

Chapter 1

, Introduction to Microservices

Chapter 2

, Diving into Microservices Internals

Chapter 3

, What Do You Need Before Getting Started?

Chapter 4

, Stack Development Technologies

1

Introduction to Microservices

As human beings, we all go through various stages of development. With each stage we reach, even if it seems like the best at the time, we later realize we still have a long way to go. Each period has its problems, and depending on their size and nature, they require different solutions.

We humans tend to simplify things. That is why we build our lives around problems and their corresponding solutions. Finding solutions to problems has been our main goal throughout history, perhaps due to our instinct to survive.

If we consider each piece of software as an individual, they also have problems to solve. Depending on the size and shape of the problems, software has a different structure, which we call architecture. The size and nature of the problems directly affect the architecture of the software. One of these architectural approaches we use is called microservices.

Microservices are important when it comes to building scalable distributed applications that respond to modern-day concerns. It is also a de facto requirement for most huge companies when they interview you as a developer. The vast majority of technologies we use nowadays try to support microservice development out of the box. So, being a software engineer without microservice knowledge doesn’t make you an ideal candidate in the modern IT world.

Starting from this chapter, we’re going to dive into the world of microservices. We will build strong theoretical knowledge before moving on to practical sections.

First, we will go back and try to understand what type of popular approaches were there before microservices. Microservices are important, but understanding the need to apply them is foremost.

In this chapter, we’re going to cover the following topics:

Introducing microservices

Exploring the monolith approach

What is service-oriented architecture?

The differences between SOA and microservices

Advantages of microservices

Disadvantages of microservices

Introducing microservices

A microservice architecture decomposes an application into loosely coupled, independently deployable services that own their data and communicate through lightweight protocols. It breaks down large applications into smaller, self-contained business capabilities, enabling faster development, easier scaling, and better fault tolerance. Microservices enable continuous delivery and agile development by allowing teams to independently build, test, and deploy features. You can imagine an application as an orchestra, where each microservice is a musician playing their part, but in perfect harmony with the others, to create a beautiful symphony.

What we’ve just mentioned sounds like a silver bullet but as you know, nothing is free and there is no one-size-fits-all solution to the problems we face. The same applies to microservices.

We, as software developers, love to learn new trends and try to apply them to our practice. But after delving into the details, we understand that every trend is just an encapsulation of old knowledge. Before applying any architecture to software, it is always better to engage in careful planning, discussion, collaboration, and analysis.

Moving toward microservices

Creating software is more than just learning a programming language and applying syntactical elements of it to code, to build things. It’s like wielding a hammer and nails; having them in your arsenal doesn’t make you a skilled builder. Similarly, having all the tools doesn’t make you a good software developer.

As you embark on creating a basic hello world type application, it remains just that – basic. However, it is important to understand that such simple applications don’t warrant payment. If you want your application to have value, it must address tangible real-world challenges – in short, it should hold business value. Adding more business value also brings complexity. In most cases, more business means more complexity. After some time, you’ll realize that instead of dealing with a business, you’re starting to deal with the complexity that your business brought to your application.

In navigating complexity, we aim to break it down into smaller, maintainable, extensible, and reusable components. Only by doing so can we effectively handle the complexity and future changes. In programming, the only true constant is the need to embrace changes, a principle that remains as-is, not just during the process of creating the application, but until the end.

This constant change forces us to not only master the selected programming language but also to have an understanding of the business domain. Naturally, this leads to us adopting a design-oriented mindset. Without having good knowledge of business, it is almost impossible to develop valuable software.

Although the simple applications we write to learn a language may seem useless, when we connect the dots, we get closer to the truth. Isn’t our whole life spent in search of truth? Soon, you’ll realize that the software that meets the customer’s business requirements is the software that matters, and that reflects the truth.

If you start your development process without carefully analyzing and designing, you’re going to pay a higher price throughout the development itself. The earlier you start with design and analysis, the less likely you are to run into a bigger problem at a later stage. We call our first not properly analyzed and designed application a big ball of mud that uses spaghetti-driven development:

In software design, the phrase a big ball of mud is used to draw attention to an anti-pattern or a design approach that produces undesirable results. Let’s understand this phrase in more depth.

Understanding a big ball of mud

The main issue with a big ball of mud is the lack of structure and organization. The absence of modularity and distinct issue separation in the code base leads to a complex network of interconnected files and functions. Imagine a house that is just a disorganized jumble of rooms and materials with no walls or other distinguishing features. Because everything in it is connected, changes that are made in one part could have a disastrous effect on other parts. It’s like pulling on a loose thread in a badly tailored sweater – you run the risk of the entire garment coming apart. Similarly code fragments are dispersed throughout the code base, which causes inefficiencies when performing maintenance.

Due to the absence of structure and documentation, maintaining the code base and adding new features is challenging for developers. Imagine attempting to navigate a house devoid of layout or labels; it’s nearly impossible.

Because of their close coupling, changes in one area can unintentionally disturb seemingly unrelated components. Because of its fragility, the software is prone to mistakes and regressions. Imagine a house built with weak, interconnected supports so that even a small outside force could result in serious harm.

A big ball of mud may seem like the right choice at first in small, simple projects,