Book Image

Docker and Kubernetes for Java Developers

By : Jarosław Krochmalski
Book Image

Docker and Kubernetes for Java Developers

By: Jarosław Krochmalski

Overview of this book

Imagine creating and testing Java EE applications on Apache Tomcat Server or Wildfly Application server in minutes along with deploying and managing Java applications swiftly. Sounds too good to be true? But you have a reason to cheer as such scenarios are only possible by leveraging Docker and Kubernetes. This book will start by introducing Docker and delve deep into its networking and persistent storage concepts. You will then proceed to learn how to refactor monolith application into separate services by building an application and then packaging it into Docker containers. Next, you will create an image containing Java Enterprise Application and later run it using Docker. Moving on, the book will focus on Kubernetes and its features and you will learn to deploy a Java application to Kubernetes using Maven and monitor a Java application in production. By the end of the book, you will get hands-on with some more advanced topics to further extend your knowledge about Docker and Kubernetes.
Table of Contents (12 chapters)
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The idea behind Docker

The idea behind Docker is to pack an application with all the dependencies it needs into a single, standardized unit for the deployment. Those dependencies can be binaries, libraries, JAR files, configuration files, scripts, and so on. Docker wraps up all of it into a complete filesystem that contains everything your Java application needs to run the virtual machine itself, the application server such as Wildfly or Tomcat, the application code, and runtime libraries, and basically everything you would install and deploy on the server to make your application run. Packaging all of this into a complete image guarantees that it is portable; it will always run in the same way, no matter what environment it is deployed in. With Docker, you can run Java applications without having to install a Java runtime on the host machine. All the problems related to incompatible JDK or JRE, wrong version of the application server, and so on are gone. Upgrades are also easy and effortless; you just run the new version of your container on the host.

If you need to do some cleanup, you can just destroy the Docker image and it's as though nothing ever happened. Think about Docker, not as a programming language or a framework, but rather as a tool that helps in solving the common problems such as installing, distributing, and managing the software. It allows developers and DevOps to build, ship, and run their code anywhere. Anywhere means also on more than one machine, and this is where Kubernetes comes in handy; we will shortly get back to it.

Having all of your application code and runtime dependencies packaged as a single and complete unit of software may seem the same as a virtualization engine, but it's far from that, as we will explain now. To fully get to know what Docker really is, first we need to understand the difference between traditional virtualization and containerization. Let's compare those two technologies now.