YAML (YAML Ain’t Markup Language) is a human-readable data serialization language that is commonly used for configuration files in various applications, including Spring Boot. YAML is easy to read and write compared to other data serialization languages such as XML or properties files.

In this post, we will show how to use YAML in a Spring Boot application to configure a list of strings.

Setting up a YAML file

To use YAML in a Spring Boot application, you need to create a YAML file in the classpath of your project. In most cases, this would be the src/main/resources folder. For this example, let’s create a file named application.yml.

  - value1
  - value2
  - value3

In this YAML file, we have defined a list of strings under the strings key.

Accessing YAML configuration in code

To access the YAML configuration in code, we use the @Value annotation in a field or setter method. The syntax of the @Value annotation is @Value("${key}"), where key is the name of the configuration property you want to access. In our example, the key is strings.

private List<String> strings;

With the above code, the list of strings defined in the application.yml file will be automatically populated into the strings field when the application starts.

Using YAML configuration

Using YAML for configuration in Spring Boot has several advantages. For example, it allows you to structure your configuration in a hierarchical way, which makes it easier to manage and maintain complex configurations. Additionally, YAML supports the use of comments, which can help to document your configuration and make it more readable.

It’s also worth mentioning that YAML supports different data types, including strings, numbers, booleans, and lists, which can come in handy when you need to configure more complex data structures.

If you are migrating from a properties file or XML configuration to YAML, you can easily convert your existing configuration by using a YAML to properties or XML converter tool. This will help you to quickly transition to YAML without having to rewrite your entire configuration.

It’s also worth mentioning that YAML has good support in various programming languages and can be used in many other applications besides Spring Boot. This makes YAML a good choice if you want to standardize your configuration format across multiple projects or applications.

When it comes to security, YAML is just as secure as other data serialization languages. However, it’s important to be mindful of the potential risks involved in using external configuration files, such as sensitive information exposure and unauthorized access. To mitigate these risks, you can use encryption and authentication methods to secure your YAML configuration files.

If you need to validate the configuration in your YAML file, you can use a YAML schema to specify the expected structure and data types of your configuration. This can help to prevent invalid configurations and ensure that your application behaves as expected.

In addition to YAML, Spring Boot also supports other configuration formats, such as properties and XML. You can use the format that best fits your needs, or even switch between formats as needed. This gives you the flexibility to choose the configuration format that works best for your specific use case.


In conclusion, using YAML for configuration in a Spring Boot application can simplify the configuration process and make it easier to manage and maintain complex configurations. Whether you are starting a new project or migrating from an existing configuration, YAML is definitely worth considering as your configuration format.

Leave a Reply