Kotlin and Microservices: A Practical Guide to Building Distributed Systems

This book is a comprehensive practical guide to building modern microservice applications in Kotlin. Unlike abstract theoretical materials, the author offers concrete, ready-to-use solutions based on years of experience developing distributed systems in production.

What is this book about?

You will journey from architecture design to deploying a finished product. The book covers all key aspects of microservice development:

• Framework selection: a detailed comparison of Ktor and Spring Boot for microservices, their strengths and weaknesses, and criteria for choosing the right one for a specific task.
• Asynchrony and coroutines: how to effectively use Kotlin coroutines to build non-blocking services with high throughput.
• Inter-service communication: REST, gRPC, message queues (Kafka, RabbitMQ) — when and what to use, practical examples.
• Configuration management: centralized configs, working with Config Server, external secrets.
• Containerization and orchestration: creating Docker images, writing Dockerfiles for Kotlin applications, basics of working with Kubernetes.
• Monitoring and observability: logging, metrics (Prometheus), tracing (Jaeger) — how to understand what is happening in the system.
• Testing: unit, integration, contract testing (Pact), testing in an isolated environment (Testcontainers).
• Security: JWT, OAuth2, inter-service authentication, API protection.

Who is this book for?

• Java and Kotlin developers who want to transition from monolithic architecture to microservices.
• Backend developers looking to master the modern Kotlin stack for distributed systems.
• Team leads and architects seeking practical patterns and anti-patterns for microservice development.
• Developers already familiar with microservices but struggling with concrete implementation in Kotlin.

What will you learn?

After reading this book, you will be able to:

• Design microservice architecture with Domain-Driven Design in mind.
• Create RESTful and gRPC services with Ktor and Spring Boot.
• Implement asynchronous interaction using coroutines and reactive streams.
• Set up CI/CD pipelines for microservices.
• Conduct load testing and optimize performance.
• Apply Circuit Breaker, Saga, CQRS, and Event Sourcing patterns.

The book contains numerous code listings, practical exercises, and links to a repository with ready-made examples. Each chapter ends with a "What's next?" section with recommendations for deeper study of the topic.

This is not a Kotlin syntax reference — it is a practical tool for those who want to build reliable, scalable, and maintainable distributed systems in one of the most modern programming languages.