In this article, you will learn how to develop and deploy Java apps on Podman, Kubernetes, and OpenShift with odo. Odo is a fast and iterative CLI tool for developers who want to write, build, and deploy applications on Kubernetes-native environments. Thanks to odo you can focus on the most important aspect of programming – code. I have already written an article about that tool in my blog some years ago. However, a lot has changed during that time. Today, we will also focus more on Podman, and especially Podman Desktop, as an alternative to the Docker Desktop for local development. You will l ..read more

In this article, you will learn how to manage Kafka consumer offset with Spring Boot and Spring Kafka. An inspiration for preparing this article was the feedback I received after publishing the post describing concurrency with Kafka and Spring Boot. You were asking me questions related not only to concurrency but also to the consumer offset committing process. In the previous article, I focused mostly on showing that the way how the app handles Kafka messages may impact the overall performance of our system. I didn’t consider things like message duplicates or losing messages on the consumer si ..read more

This article will teach you how to dynamically create and rotate SSL certificates used in service-to-service communication with OpenShift and Spring Boot. We will achieve it with a single annotation on a Kubernetes service and the “SSL Bundles” mechanism introduced in Spring Boot 3.1. For generating the SSL on OpenShift, we will use the mechanism called “Service Serving Certificates”. It generates a certificate and key in PEM format. With Spring Boot 3.1 SslBundles, it won’t be a problem for our Java app, since it supports PEM-encoded certificates. The “Service Serving Certificates” mechanism ..read more

This article will teach you how to use Keycloak to enable OAuth2 for Spring Cloud Gateway and Spring Boot microservices. We will extend the topics described in my previous article and analyze some of the latest features provided within the Spring Security project. Our architecture consists of two Spring Boot microservices, an API gateway built on top of Spring Cloud Gateway, and a Keycloak authorization server. Spring Cloud Gateway acts here as an OAuth2 Client and OAuth2 Resource Server. For any incoming request, it verifies an access token before forwarding traffic to the downstream services ..read more

This article will teach you how to configure a hot reload of SSL certificates for the Spring Boot app running on Kubernetes. We will use the two features introduced in the 3.1 and 3.2 versions of the Spring Boot framework. The first of them allows us to leverage SSL bundles for configuring and consuming a custom SSL trust material on both the server and client sides. The second one makes it easy to hot reload SSL certificates and keys for embedded web servers in the Spring Boot app. Let’s see how it works in practice! In order to generate SSL certificates on Kubernetes we will use cert-manager ..read more

This article will teach you how to automate your Spring Boot app deployment with Azure DevOps and Terraform. In the previous article in this series, we created a simple Spring Boot RESTful app. Then we integrated it with the popular Azure services like Cosmos DB or App Configuration using the Spring Cloud Azure project. We also leveraged the Azure Spring Apps service to deploy, run, and manage our app on the Azure cloud. All the required steps have been performed with the az CLI and Azure Portal. Today, we are going to design the CI/CD process for building and deploying the app created in the ..read more

This article will teach you how to use Spring Cloud to simplify integration between Spring Boot apps and Azure services. We will also see how to leverage the Azure Spring Apps service to deploy, run, and manage our app on Azure. Our sample Spring Boot app stores data in the Azure Cosmos DB service and exposes some REST endpoints under the public URL. We can run it locally and connect remote services or deploy it on the cloud and connect those services internally under the same virtual network. If you need an introduction to Spring Cloud read my article about microservices with Spring Boot 3 an ..read more

In this article, you will learn how to configure tracing for Kafka producer and consumer with Spring Boot and Open Telemetry. We will use the Micrometer library for sending traces and Jaeger for storing and visualizing them. Spring Kafka comes with built-in integration with Micrometer for the KafkaTemplate and listener containers. You will also see how to configure the Spring Kafka observability to add our custom tags to traces. If you are interested in Kafka and Spring Boot, you may find several articles on my blog about it. To read about concurrency with Kafka and Spring Boot read the follow ..read more

In this article, you will learn how to build slim Docker images for your Java apps using Alpine Linux and the jlink tool. We will leverage the latest Java 21 base images provided by Eclipse Temurin and BellSoft Liberica. We are going to compare those providers with Alpaquita Linux also delivered by BellSoft. That comparison will also include security scoring based on the number of vulnerabilities. As an example, we will use a simple Spring Boot app that exposes some REST endpoints. If you are interested in Java in the containerization context you may find some similar articles on my blog. For ..read more

This article will teach you how to build modulith with Spring Boot and use the Spring Modulith project features. Modulith is a software architecture pattern that assumes organizing your monolith app into logical modules. Such modules should be independent of each other as much as possible. Modulith balances monolithic and microservices-based architectures. It can be your target model for organizing the app. But you can also treat it just as a transitional phase during migration from the monolithic into a microservices-based approach. Spring Modulith will help us build a well-structured Sp ..read more