When we use Helidon SE we can use the Config class to pass configuration properties to our application. The static method create() creates a default configuration. The Config class is then configured to support different input sources. This configuration reads configuration properties from the following sources in order:

The last input source behaves differently based on which classes that can parse a configuration file are on the classpath of our application. If we use the helidon-config artifact on the classpath then the configuration file read is application.properties. To read a JSON formatted configuration file we must add the helidon-config-hocon artifact to the classpath. The file that is read is application.json. With the same artifact we can read a HOCON formatted configuration file that is named application.conf. Finally if we add the helidon-config-yaml artifact to the classpath we can read a YAML formatted configuration file that is named application.yaml or application.yml. Helidon SE will only read one configuration file from the classpath with the following order of preference: