5 Spring Boot Mistakes to Avoid

Spring Boot features that took me years to discover (wish someone had told me sooner): 1. @ConfigurationProperties over @Value   Stop injecting individual properties   Bind entire configuration blocks to typed classes   You get validation for free with @Validated 2. Actuator /health with custom indicators   Don't just expose the default health check   Add checks for your downstream dependencies   Your ops team will thank you at 2am 3. @Async with proper thread pool config   Spring's default Async executor is a thread-per-task executor   Configure ThreadPoolTaskExecutor with proper bounds   Unbounded queues + async = memory leak waiting to happen 4. @Transactional pitfalls   Self-invocation bypasses the proxy   readOnly=true is an optimization hint, not a guarantee   Understand your propagation levels 5. Spring Boot DevTools for productivity   Automatic restart, LiveReload, property defaults   Should be in every developer's setup 6. Profiles done right   application-{profile}.yml not just one giant file   Never put secrets in application.yml   Use Spring Cloud Config or environment variables for production What Spring Boot feature do you wish you'd known earlier? #Java #SpringBoot #Backend #SoftwareEngineering #Microservices

Great list. Adding a few things that took me just as long to figure out. One that does not get talked about enough is Hibernate's truncateMappedObjects() for integration test cleanup. Most engineers wrap their tests in @Transactional and call it done. The problem is that a transaction that never commits is not testing what actually runs in production. FlushMode never triggers, LazyInitializationExceptions that would blow up in prod pass silently, and database constraints never get validated. Using SchemaManager to truncate before each test and letting the service layer own its transactions gives you real production-equivalent behavior in your test suite. Another one is DataSource-Proxy over spring.jpa.show-sql. The built-in property only prints SQL to console with no bind parameter values and no batching visibility. DataSource-Proxy gives you all of that and lets you automatically detect N+1 query issues during testing before they ever reach production. Most engineers also do not realize that Resilience4j integrates directly into Spring Boot via application.yml with zero custom code. Circuit breaker, retry with exponential backoff, rate limiter and bulkhead all configurable as beans. By the time you write a custom retry mechanism from scratch, this was already available in your dependency tree. Flyway is another one that looks optional until the day a schema change goes to production without a migration script and takes down your application. Schema changes versioned and applied automatically on startup, the same way across every environment. Once you use it you cannot imagine managing databases without it. The last one is @TransactionalEventListener. Most engineers use @EventListener for application events but it fires regardless of transaction outcome. @TransactionalEventListener fires only after the transaction successfully commits. For things like sending emails, pushing to a message queue, or triggering downstream calls after a database write, this is the correct tool. Using @EventListener for those cases means your side effects fire even when the transaction rolls back.

Spring Boot Magic #4 ✨ — Starter Dependencies One thing I feel is underrated in Spring Boot… is how powerful starter dependencies actually are. We use them every day, but rarely think about how much work they’re saving us. Just add one dependency… and boom 💥 Everything is auto-configured and ready to use. Some underrated but super useful starters 👇 👉 spring-boot-starter-validation Handle validations with simple annotations like @NotNull, @Email — clean & easy 👉 spring-boot-starter-data-jpa No need to write basic SQL — just interfaces and you’re good to go 👉 spring-boot-starter-security Add authentication & authorization with minimal setup 👉 spring-boot-starter-actuator Production-ready endpoints for health, metrics, monitoring 👉 lombok (not a starter but a lifesaver 😄) Removes boilerplate like getters, setters, constructors We use these almost daily… but don’t always realize how much complexity they hide. Sometimes, the real magic is just one dependency away 🚀 #SpringBoot #Java #BackendDevelopment #CleanCode #DeveloperLife

Java just solved its 20-year cold-start problem — and most EKS teams don't know it yet. Spring Boot 4.0 ships with full Project Leyden support, and Java 26's JEP 516 pushes Ahead-of-Time Object Caching further still — your Kubernetes pods now reach a useful state significantly faster, with zero changes to application code, framework config, or deployment tooling. I've watched Spring Boot services sit at 12–15 second startup times on EKS while Go services mocked us. We worked around it — bigger readiness probe delays, over-provisioned pod counts, aggressive pre-warming. All of it unnecessary tax. The key insight is that you build the AOT cache once in your CI pipeline and ship it as part of your container image. Every pod that spins up loads the same cache file — training overhead paid once, every deployment run benefits. That's a Dockerfile layer change, not an architecture rewrite. If you're on Spring Boot 3.3+ and JDK 25 today, you can start experimenting right now with three JVM flags. No GraalVM. No native-image pain. No reflection debugging at 2am. Is your team still paying the cold-start tax — or have you already moved off JVM warm-up workarounds? #SpringBoot #JavaDeveloper #CloudNative #AWSArchitect #MicroservicesArchitecture

Ever wondered how Spring Boot sets up a DataSource, EntityManagerFactory, and transactions — without you writing a single line of config? That's auto-configuration. And I just wrote my first blog post breaking down exactly how it works. What's covered: → The role of META-INF/spring/AutoConfiguration.imports → @ConditionalOnClass, @ConditionalOnMissingBean, @ConditionalOnProperty → How condition evaluation happens before any bean is created If you've ever typed @SpringBootApplication and moved on without questioning it — this one's for you. This is my first blog, so if I've missed anything or something could be explained better — feel free to drop a comment. Happy to discuss and improve! 🔗 Link in the comments! #SpringBoot #Java #Backend

I recently worked on containerizing a Spring Boot application using Docker, and it was a great hands-on experience in understanding how deployment works in real-world scenarios. The application I built is a simple REST API that returns the message “Hello Namaste” when accessed through a browser. I started by developing the Spring Boot application with a basic controller that handles HTTP requests and returns the response. Once the application was ready, I packaged it into a JAR file using Maven with the command mvn clean package. This generated the required JAR file inside the target folder. Next, I created a Dockerfile in the root directory of my project. In the Dockerfile, I used an OpenJDK base image, added the generated JAR file into the container, and specified the entry point to run the application. This step helped define how my application should run inside a container. After that, I built a Docker image using the command docker build -t rest-demo .. This created an image of my application along with all necessary dependencies. Then, I ran the container using docker run -p 8081:8081 rest-demo, which allowed me to access the application on my local machine. Finally, when I opened http://localhost:8081/, I successfully got the output “Hello Namaste”, confirming that my Spring Boot application was running inside a Docker container. Through this process, I learned how Docker helps in making applications portable, consistent, and easy to deploy across different environments. #Docker #SpringBoot #Java #Maven #DevOps #Containerization #Microservices #BackendDevelopment #CloudComputing #SoftwareDevelopment #Programming #Tech #Learning #OpenJDK #RESTAPI #WebDevelopment #BuildAndDeploy #DeveloperLife

What actually happens when you hit a Spring Boot API? In my previous post, I explained how Spring Boot works internally. Now let’s go one level deeper 👇 What happens when a request hits your application? --- Let’s say you call: 👉 GET /users Here’s the flow behind the scenes: 1️⃣ Request hits embedded server (Tomcat) Spring Boot runs on an embedded server that receives the request. --- 2️⃣ DispatcherServlet takes control This is the core of Spring MVC. It acts like a traffic controller. --- 3️⃣ Handler Mapping DispatcherServlet finds the correct controller method for the request. --- 4️⃣ Controller Execution Your @RestController handles the request → Calls service layer → Fetches data from DB --- 5️⃣ Response conversion Spring converts the response into JSON using Jackson. --- 6️⃣ Response sent back Finally, the client receives the response. --- Why this matters? Understanding this flow helps in: ✔ Debugging production issues ✔ Writing better APIs ✔ Improving performance Spring Boot hides complexity… But knowing what’s inside makes you a better backend developer. More deep dives coming #Java #SpringBoot #BackendDevelopment #Microservices

🚀 Spring Boot: More Than Just REST! I recently created this visual to better understand how Spring Boot simplifies application development using powerful features like auto-configuration, dependency injection, and embedded servers. This diagram highlights how different components—Controller, Service, Repository, and Database—work together seamlessly within the Spring ecosystem. Building visuals like this really helps me connect concepts with real-world application flow 💡 📌 Always learning, always improving! #SpringBoot #Java #BackendDevelopment #SoftwareEngineering #LearningJourney #FullStackDeveloper #Tech

Spring Boot 4.1.0-M4 is out now and if you are using M3 there is something you should know. They changed their mind about the RabbitMQ updates. So if you made changes to those settings you need to change them Also that problem where the application.properties file was not working right? It is fixed now. Now let us look at the picture. Spring Boot 4 is like a new beginning. It uses Spring Framework 7. It needs JDK 17 to work. It also has some features like trying again if something fails and it is safer when dealing with empty values. It even supports versions of REST without needing extra work. If you are still using Boot 3.x do not worry. They also released 3.5.13 on the day. You are not behind. If you are starting a new project in 2026 Spring Boot 4 is the way to go. You should start reading the guide on how to move to Boot 4 before your team tells you to do it when you're, in a hurry. #SpringBoot #Java #BackendDevelopment #FullStackDeveloper #SoftwareEngineering #JavaDeveloper #REST #SpringFramework #Microservices #Coding #SoftwareDeveloper #TechNews #OpenSource #DeveloperLife

⚠️ 5 Common mistakes developers make in Spring Boot (I’ve made some of these too) After working with Spring Boot in real projects, I’ve seen a few mistakes that can cause serious issues later. Here are some important ones 👇 --- 1️⃣ Putting everything in Controller ❌ Business logic inside controller ✅ Use Service layer for logic 👉 Keeps code clean & maintainable --- 2️⃣ Not handling exceptions properly ❌ Try-catch everywhere ✅ Use @ControllerAdvice for global exception handling --- 3️⃣ Ignoring proper logging ❌ Using System.out.println ✅ Use logging frameworks (SLF4J + Logback) --- 4️⃣ Not using DTOs ❌ Exposing entity directly in APIs ✅ Use DTOs to control data flow --- 5️⃣ Too many database calls ❌ Multiple queries in loops ✅ Optimize using joins / batch operations --- 💡 Key takeaway: Spring Boot makes development fast… But writing clean, scalable code is still your responsibility. Avoiding these mistakes early can save a lot of time in production. I’m sharing these based on my experience — hope it helps someone 👍 #Java #SpringBoot #BackendDevelopment #Microservices