Kotlin and Docker: Application Containerization

Modern software development is unthinkable without containerization. If you write in Kotlin and want to learn how to package your applications into lightweight, portable, and scalable containers — this book is for you. It will be your guide to the world of Docker, adapted specifically for the Kotlin and JVM ecosystem.

What is this book about?

The book "Kotlin and Docker: Containerizing Applications" is a practical guide that will take you step by step from creating your first Docker image to deploying a full-fledged microservice application in a production environment. You will learn how to effectively combine the power of the Kotlin language (including coroutines and Ktor) with the flexibility of Docker and orchestration.

Main topics:

• Basic Docker concepts — images, containers, Dockerfile, layers, and caching.
• Building Kotlin applications — creating multi-module projects, optimizing image size (Distroless, Alpine, JLink).
• Working with Spring Boot, Ktor, and Micronaut — configuring containers for popular frameworks.
• Docker Compose — orchestrating databases, message queues, and services.
• Monitoring and logging — setting up health checks, collecting metrics (Prometheus), and centralized logging.
• CI/CD and deployment — integration with GitHub Actions, GitLab CI, and Kubernetes.

Who is this book for?

• Kotlin backend developers looking to master containerization.
• DevOps engineers who want to gain a deeper understanding of how JVM applications work in containers.
• Team Leads and architects planning a transition to a microservice architecture.
• Students and beginner programmers familiar with the basics of Kotlin.

What will you learn?

• How to build a minimal Docker image for a Kotlin application (under 50 MB).
• How to avoid common mistakes when working with memory, CPU, and the file system in containers.
• How to set up hot reload for Ktor in a container.
• How to securely store secrets and environment variables.
• How to test multi-container applications locally.

The book contains many ready-made code examples, Dockerfiles, and docker-compose.yml files that you can adapt for your own projects. All examples are available in a GitHub repository and have been tested with current versions of Kotlin 2.x and Docker 24+.

Whether you are working on a startup or a large corporate project, containerization will be your competitive advantage. Start your journey into the world of Docker and Kotlin today!