Quarkus - Configuring Your Application

Hardcoded values in your code are a no go (even if we all did it at some point ;-)). In this guide, we learn how to configure your application.

Prerequisites

To complete this guide, you need:

  • between 5 and 10 minutes

  • an IDE

  • JDK 1.8+ installed with JAVA_HOME configured appropriately

  • Apache Maven 3.6.2+

Solution

We recommend that you follow the instructions in the next sections and create the application step by step. However, you can go right to the completed example.

Clone the Git repository: git clone https://github.com/quarkusio/quarkus-quickstarts.git, or download an archive.

The solution is located in the config-quickstart directory.

Creating the Maven project

First, we need a new project. Create a new project with the following command:

mvn io.quarkus:quarkus-maven-plugin:1.12.0.Final:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=config-quickstart \
    -DclassName="org.acme.config.GreetingResource" \
    -Dpath="/greeting"
cd config-quickstart

It generates:

  • the Maven structure

  • a landing page accessible on http://localhost:8080

  • example Dockerfile files for both native and jvm modes

  • the application configuration file

  • an org.acme.config.GreetingResource resource

  • an associated test

Create the configuration

By default, Quarkus reads configuration properties from several sources. For the purpose of this guide, we will use an application configuration file located in src/main/resources/application.properties. Edit the file with the following content:

# Your configuration properties
greeting.message = hello
greeting.name = quarkus

Injecting configuration properties

Quarkus uses MicroProfile Config annotations to inject the configuration properties in the application.

@ConfigProperty(name = "greeting.message") (1)
String message;
1 You can use @Inject @ConfigProperty or just @ConfigProperty. The @Inject annotation is not necessary for members annotated with @ConfigProperty. This behavior differs from MicroProfile Config.
If the application attempts to inject a configuration property that is not set, an error is thrown. So you can quickly know when your configuration is complete.

Edit the org.acme.config.GreetingResource, and introduce the following configuration properties:

@ConfigProperty(name = "greeting.message") (1)
String message;

@ConfigProperty(name = "greeting.suffix", defaultValue="!") (2)
String suffix;

@ConfigProperty(name = "greeting.name")
Optional<String> name; (3)
1 If you do not provide a value for this property, the application startup fails with javax.enterprise.inject.spi.DeploymentException: No config value of type [class java.lang.String] exists for: greeting.message.
2 The default value is injected if the configuration does not provide a value for greeting.suffix.
3 This property is optional - an empty Optional is injected if the configuration does not provide a value for greeting.name.

Now, modify the hello method to use the injected properties:

@GET
@Produces(MediaType.TEXT_PLAIN)
public String hello() {
    return message + " " + name.orElse("world") + suffix;
}

Once set, check the application with:

$ curl http://localhost:8080/greeting
hello quarkus!
As an alternative to injecting multiple related configuration values, you can also use the @io.quarkus.arc.config.ConfigProperties annotation to group these properties together. See the Configuration Reference Guide for more information.

Update the test

We also need to update the functional test to reflect the changes made to the endpoint. Edit the src/test/java/org/acme/config/GreetingResourceTest.java file and change the content of the testHelloEndpoint method to:

package org.acme.config;

import io.quarkus.test.junit.QuarkusTest;
import org.junit.jupiter.api.Test;

import static io.restassured.RestAssured.given;
import static org.hamcrest.CoreMatchers.is;

@QuarkusTest
public class GreetingResourceTest {

    @Test
    public void testHelloEndpoint() {
        given()
          .when().get("/greeting")
          .then()
             .statusCode(200)
             .body(is("hello quarkus!")); // Modified line
    }

}

Package and run the application

Run the application with: ./mvnw compile quarkus:dev. Open your browser to http://localhost:8080/greeting.

Changing the configuration file is immediately reflected. You can add the greeting.suffix, remove the other properties, change the values, etc.

As usual, the application can be packaged using ./mvnw clean package and executed using the target/quarkus-app/quarkus-run.jar file. You can also generate the native executable with ./mvnw clean package -Pnative.

Programmatically access the configuration

You can also access the configuration programmatically. It can be handy to achieve dynamic lookup, or retrieve configured values from classes that are neither CDI beans or JAX-RS resources.

You can access the configuration programmatically using org.eclipse.microprofile.config.ConfigProvider.getConfig() such as in:

String databaseName = ConfigProvider.getConfig().getValue("database.name", String.class);
Optional<String> maybeDatabaseName = ConfigProvider.getConfig().getOptionalValue("database.name", String.class);

Configuration Profiles

Quarkus supports the notion of configuration profiles. These allow you to have multiple configuration values in the same file and select between them via a profile name.

The syntax for this is %{profile}.config.key=value. For example if I have the following:

quarkus.http.port=9090
%dev.quarkus.http.port=8181

Then the Quarkus HTTP port will be 9090, unless the dev profile is active, in which case it will be 8181.

See the Configuration Reference Guide for more information about configuration profiles.

Configuring Quarkus

Quarkus itself is configured via the same mechanism as your application. Quarkus reserves the quarkus. namespace for its own configuration. For example to configure the HTTP server port you can set quarkus.http.port in application.properties. All the Quarkus configuration properties are documented and searchable.

As mentioned above, properties prefixed with quarkus. are effectively reserved for configuring Quarkus itself and therefore quarkus. should never be used as prefix for application specific properties.

In the previous examples using quarkus.message instead of greeting.message would result in unexpected behavior.

Quarkus does much of its configuration and bootstrap at build time and some configuration properties are read and used during the build. These properties are fixed at build time and it’s not possible to change them at runtime. You always need to repackage your application in order to reflect changes of such properties.

The properties fixed at build time are marked with a lock icon () in the list of all configuration options.

However, some extensions do define properties overridable at runtime. A canonical example is the database URL, username and password which is only known specifically in your target environment.

  1. System properties

  2. Environment variables

  3. An environment file named .env placed in the current working directory

  4. A configuration file placed in $PWD/config/application.properties

See the Configuration Reference Guide for more information.