Micronaut is a versatile framework for building microservices and serverless applications, known for its flexibility and minimal footprint. It’s no surprise that many developers prefer configuring Micronaut applications using YAML files for their readability and structure. However, you might encounter an issue where Micronaut fails to read properties from your application.yml file. Let’s dive into this problem and explore the solution.

The Problem

Imagine you’ve created a Micronaut project and started adding properties to your application.yml file, like database connection details, server ports, and other configuration options. But when you run your application, you notice that it doesn’t pick up these properties, and you’re left scratching your head.

The Missing Piece

The culprit behind this issue is often a missing dependency. Unlike application.properties, which Micronaut can read without any extra configuration, application.yml relies on the SnakeYAML library to parse the YAML format.

The Solution

To resolve this problem, you need to explicitly include the SnakeYAML library as a dependency in your project. Here’s how to do it:

1. Open Your Build File: Depending on whether you’re using Gradle or Maven, open your project’s build file.
2. Add SnakeYAML Dependency: Insert the SnakeYAML dependency into your project’s dependencies section. Below are examples for both Gradle and Maven:

dependencies {
    implementation "org.yaml:snakeyaml:1.29" // Use the latest version if available
}

Maven (In the pom.xml file)

<dependencies>
    <dependency>
        <groupId>org.yaml</groupId>
        <artifactId>snakeyaml</artifactId>
        <version>1.29</version> <!-- Use the latest version if available -->
    </dependency>
</dependencies>

3. Sync or Refresh Dependencies: After adding the dependency, sync your Gradle project or refresh your Maven project to download the SnakeYAML library.

4. Restart Your Application: Stop and restart your Micronaut application. It should now correctly read properties from your application.yml file.

Conclusion

While Micronaut’s compatibility with application.properties is seamless, reading properties from application.yml requires you to include the SnakeYAML library explicitly. Once you’ve added this dependency, you can enjoy the readability and structure that YAML offers for configuring your Micronaut applications.

Don’t let configuration hiccups slow down your development. By following these steps, you can ensure that your Micronaut application smoothly reads properties from your application.yml file, allowing you to focus on building fantastic microservices and serverless apps.