This guide explains how your Quarkus application can read configuration properties at runtime from the Spring Cloud Config Server.

Prerequisites

To complete this guide, you need:

  • Roughly 15 minutes

  • An IDE

  • JDK 17+ installed with JAVA_HOME configured appropriately

  • Apache Maven ${proposed-maven-version}

  • Optionally the Quarkus CLI if you want to use it

  • Optionally Mandrel or GraalVM installed and configured appropriately if you want to build a native executable (or Docker if you use a native container build)

Solution

We recommend that you follow the instructions in the next sections and create the application step by step.

Stand up a Config Server

To stand up the Config Server required for this guide, please follow the instructions outlined here. The end result of that process is a running Config Server that will provide the Hello world value for a configuration property named message when the application querying the server is named a-bootiful-client.

Creating the Maven project

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

CLI
quarkus create app org.acme:spring-cloud-config-quickstart \
    --extension='rest,spring-cloud-config-client' \
    --no-code
cd spring-cloud-config-quickstart

To create a Gradle project, add the --gradle or --gradle-kotlin-dsl option.

For more information about how to install and use the Quarkus CLI, see the Quarkus CLI guide.

Maven
mvn io.quarkus.platform:quarkus-maven-plugin:${project.version}:create \
    -DprojectGroupId=org.acme \
    -DprojectArtifactId=spring-cloud-config-quickstart \
    -Dextensions='rest,spring-cloud-config-client' \
    -DnoCode
cd spring-cloud-config-quickstart

To create a Gradle project, add the -DbuildTool=gradle or -DbuildTool=gradle-kotlin-dsl option.

For Windows users:

  • If using cmd, (don’t use backward slash \ and put everything on the same line)

  • If using Powershell, wrap -D parameters in double quotes e.g. "-DprojectArtifactId=spring-cloud-config-quickstart"

This command generates a project which imports the spring-cloud-config-client extension.

If you already have your Quarkus project configured, you can add the spring-cloud-config-client extension to your project by running the following command in your project base directory:

CLI
quarkus extension add spring-cloud-config-client
Maven
./mvnw quarkus:add-extension -Dextensions='spring-cloud-config-client'
Gradle
./gradlew addExtension --extensions='spring-cloud-config-client'

This will add the following to your build file:

pom.xml
<dependency>
    <groupId>io.quarkus</groupId>
    <artifactId>quarkus-spring-cloud-config-client</artifactId>
</dependency>
build.gradle
implementation("io.quarkus:quarkus-spring-cloud-config-client")

GreetingController

First, create a simple GreetingResource Jakarta REST resource in the src/main/java/org/acme/spring/cloud/config/client/GreetingResource.java file that looks like:

package org.acme.spring.spring.cloud.config.client;

import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

@Path("/hello")
public class GreetingResource {

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return "hello";
    }
}

As we want to use configuration properties obtained from the Config Server, we will update the GreetingResource to inject the message property. The updated code will look like this:

package org.acme.spring.spring.cloud.config.client;

import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.Produces;
import jakarta.ws.rs.core.MediaType;

import org.eclipse.microprofile.config.inject.ConfigProperty;

@Path("/hello")
public class GreetingResource {

    @ConfigProperty(name = "message", defaultValue="hello default")
    String message;

    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String hello() {
        return message;
    }
}

Configuring the application

Quarkus provides various configuration knobs under the quarkus.spring-cloud-config root. For the purposes of this guide, our Quarkus application is going to be configured in application.properties as follows:

# use the same name as the application name that was configured when standing up the Config Server
quarkus.application.name=a-bootiful-client
# enable retrieval of configuration from the Config Server - this is off by default
quarkus.spring-cloud-config.enabled=true
# configure the URL where the Config Server listens to HTTP requests - this could have been left out since http://localhost:8888 is the default
quarkus.spring-cloud-config.url=http://localhost:8888

If you are using Gradle, the Gradle setting rootProject.name has precedence over quarkus.application.name so be sure to set the Gradle property to the application name you want the Spring Cloud Config server to see.

Package and run the application

Run the application with:

CLI
quarkus dev
Maven
./mvnw quarkus:dev
Gradle
./gradlew --console=plain quarkusDev

Open your browser to http://localhost:8080/greeting.

The result should be: Hello world as it is the value obtained from the Spring Cloud Config server.

Run the application as a native executable

You can of course create a native image using the instructions of the Building a native executable guide.

More Spring guides

Quarkus has more Spring compatibility features. See the following guides for more details:

Spring Cloud Config Client Reference