With @ConfigurationProperties in Spring Boot we can bind configuration properties to Java classes. The class annotated with @ConfigurationProperties can be injected into other classes and used in our code. We can use the type Duration to configure properties that express a duration. When we set the value of the property we can use:

With @ConfigurationProperties in Spring Boot we can bind configuration properties to Java classes. The class annotated with @ConfigurationProperties can be injected into other classes and used in our code. We can use the type DataSize to configure properties that express a size in bytes. When we set the value of the property we can use a long value. The size is then in bytes as that is the default unit. We can also add a unit to the value. Valid units are B for bytes, KB for kilobytes, MB for megabytes, GB for gigabytes and TB for terabytes.

We can also use the @DataSizeUnit annotation to specify the unit of the property in our class annotated with @ConfigurationProperties. In that case a the value without a unit assigned to the property is already in the specified unit.

Spring Boot 3 requires at least Java 17, but that also means the Java version used by Gradle must also be at least 17. Otherwise we will get the following error message when we build our Spring Boot project in IntelliJ using Gradle:

The issue is that the Spring Boot Gradle plugin 3.1.5 requires Java 17, but our project is using Java 11. We can fix this by explicitly setting the Java version that Gradle uses in IntelliJ. Go to Settings > Build, Execution, Deployment > Build Tools > Gradle and change the JVM used for Gradle to a JDK version of at least version 17.

WireMock is a stub framework that helps you create stubs for outgoing HTTP traffic during your tests. Most people use WireMock in their test suite during build time of the application. Spin up the WireMock server, configure some stub rules, run the application tests, and tear everything down. This is a good way of testing your HTTP clients, using real traffic towards an external server.

When consuming event streams in Apache Kafka, there are various ways of handling exceptions. This blog post will give a detailed example of publishing dead-letter records with Spring Kafka. Areas where we deviate from the defaults will be highlighted, along with the considerations, and tests are provided.

A Spring Boot application typically consists of several components handling the business functionality and probably some configuration to configure all these components. This configuration consists of defining some properties, setting up some beans with the right conditions and dependencies and wrapping it all together into a class structure. Nevertheless, the configuration of our Spring Boot application is also code. Let’s threat is as code.

In this blog we will se how we can improve our Spring Boot Configuration by splitting up the configuration from the properties and how this effects the design principles.

WebFlux is the reactive web framework for Spring. The programming model is easy but using it could be cumbersome if you don’t know the consequences when used incorrectly. This post will show what the consequences are when the reactive-stack is not used correctly. It will answer the question: why is my (health) endpoint sometimes so slow?

TL DR; Don’t block the event loop

Spring offers several frameworks to implement server side rendered web pages and REST APIS. In this blog I compare three options:

When creating a Spring Boot Rest service, you can configure Spring to convert a LocalDateTime to display as a ISO-8601 date string when returning a JSON response. To get this working you have to do a few things. Firstly, you need the following dependency: com.fasterxml.jackson.datatype:jackson-datatype-jsr310

This dependency has all the JSON serialisers and deserialisers for the Java 8 time API, and when you use Spring Boot with auto configuration, it should load all the correct serialisers. Secondly, you need to add the following to your application properties: