https://devops-monk.com/tags/docker/Recent content in Docker on Devops MonkHugoen-usSun, 03 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/spring-boot/spring-boot-docker/Sun, 03 May 2026 00:00:00 +0000https://devops-monk.com/tutorials/spring-boot/spring-boot-docker/Packaging your Spring Boot application as a Docker container is the standard way to deploy it — to Kubernetes, cloud platforms, or any container runtime. This article covers building production-quality images. The Naive Dockerfile (Don’t Use This) FROM eclipse-temurin:21-jdk COPY target/order-service.jar app.jar ENTRYPOINT ["java", "-jar", "app.jar"] Problems: 600MB+ image (JDK, not JRE) No layer caching — every code change rebuilds the whole JAR layer Runs as root (security risk) No health check Layered JARs (Better Cache Utilization) Spring Boot 3 creates layered JARs by default.https://devops-monk.com/2026/05/spring-boot-docker-guide/Sun, 03 May 2026 00:00:00 +0000https://devops-monk.com/2026/05/spring-boot-docker-guide/There are three ways to containerise a Spring Boot application: a naive single-stage Dockerfile, a proper multi-stage Dockerfile with layered JARs, and Cloud Native Buildpacks. Each has different tradeoffs in build speed, image size, and maintenance overhead. This guide covers all three approaches, explains why layered JARs matter for CI/CD speed, and shows how to produce small, secure, production-ready images. The Problem with the Naive Dockerfile Most tutorials show this:https://devops-monk.com/2026/05/spring-boot-testcontainers/Sun, 03 May 2026 00:00:00 +0000https://devops-monk.com/2026/05/spring-boot-testcontainers/Testcontainers spins up real Docker containers for your tests — a real PostgreSQL database, a real Redis, a real Kafka broker. No more mocking JDBC connections or in-memory H2 databases that behave differently from production. Spring Boot 3.1 added @ServiceConnection, which removes the boilerplate of configuring connection URLs manually. This guide covers the right patterns for fast, reliable integration tests with Testcontainers. Why Testcontainers Over H2 Teams use H2 in-memory databases for testing because it’s fast.