Chapter 1. Configuring your Red Hat build of Quarkus applications by using a YAML file

You can use configuration options to change the settings of your application in a single configuration file. Red Hat build of Quarkus supports configuration profiles that you can use to group related properties and switch between profiles as required.

By default, Quarkus reads properties from the application.properties file located in the src/main/resources directory. You can also configure Quarkus to read properties from a YAML file instead.

When you add the quarkus-config-yaml dependency to your project pom.xml file, you can configure and manage your application properties in the application.yaml file. For more information, see Adding YAML configuration support.

Red Hat build of Quarkus also supports MicroProfile Config, which you can use to load your application’s configuration from other sources.

You can use the MicroProfile Config specification from the Eclipse MicroProfile project to inject configuration properties into your application and access them by using a method defined in your code.

Quarkus can also read application properties from different origins, including the following sources:

Red Hat build of Quarkus supports YAML configuration files through the SmallRye Config implementation of Eclipse MicroProfile Config. You can add the Quarkus Config YAML extension and use the YAML configuration file over the properties file for configuration. Quarkus supports the use of application.yml and application.yaml as the name of the YAML file.

The YAML configuration file takes precedence over the application.properties file. To avoid errors, you can delete the application.properties file and use only one type of configuration file.

You can combine property references and text strings into property expressions and use these expressions as values in your Quarkus configuration.

Like variables, property expressions substitute configuration property values dynamically, avoiding hard-coded values.

You can expand an expression in one configuration source with a value defined in another.

The application resolves a property expression when java.util.Properties reads the property value from a configuration source: at compile time if read then, and at runtime if overridden at that point.

If the application cannot resolve the value of a property in an expression, and the property does not have a default value, your application throws a NoSuchElementException error.

mach: 3
x:
  factor: 2.23694

display:
  mach: ${mach}
  unit:
    name: "mph"
    factor: ${x.factor}

To configure your application properties at runtime, add your application.yaml file to the config directory.

When config/application.yaml and src/main/resources/application.yaml share properties, values from config/application.yaml override those in src/main/resources/application.yaml.

Ensure that the config/application.yaml file is in the root of the working directory relative to the Quarkus application runner, as outlined in the following example:

├── config
│    └── application.yaml
├── my-app-runner

Structured formats such as YAML only support a subset of the possible configuration namespace. The following procedure shows how to resolve a conflict between two configuration properties, quarkus.http.cors and quarkus.http.cors.methods, where one property is the prefix of another.