Using MicroProfile Config

Table of Contents

Prerequisites
Configure Your App to make use of MicroProfile Config
- Add Dependency on the WildFly MicroProfile BOM
- Add Dependency to MicroProfile Config API
Use the MicroProfile Config API
What’s next?
References

In this guide, you will learn how to setup and use Eclipse MicroProfile Config in your application.

Prerequisites

To complete this guide, you need:

Roughly 10 minutes
JDK 11+ installed with JAVA_HOME configured appropriately
Apache Maven 3.9+

Configure Your App to make use of MicroProfile Config

In order to use MicroProfile Config in your application, you need to update the Maven pom.xml at different places:

Add a dependency on WildFly BOM for MicroProfile in the <dependencyManagement> section
Add a dependency on the MicroProfile Config API in the <dependencies> section

Once these 2 steps have been completed, you will be able to use MicroProfile Config in your application.

Add Dependency on the WildFly MicroProfile BOM

You need to add a dependency on the WildFly MicroProfile BOM org.wildfly.bom:wildfly-microprofile in the <dependencyManagement> section so your application will use the correct version of the MicroProfile Config provided by WildFly.

The dependency is defined as:

<dependency>
    <groupId>org.wildfly.bom</groupId>
    <artifactId>wildfly-microprofile</artifactId>
    <version>${version.wildfly}</version>
    <type>pom</type>
    <scope>import</scope>
</dependency>

It must be added to the <dependencyManagement> of your pom.xml:

<dependencyManagement>
    <dependencies>
    ...
    <!-- copy the dependency here -->
    </dependencies>
</dependencyManagement>

Note	WildFly BOMS are the only dependencies that must be added to the `<dependencyManagement><dependencies>` section. Other dependencies are added directly to the `<dependencies>` section of the Maven `pom`.xml.

Add Dependency to MicroProfile Config API

Next, you need to add a dependency on the MicroProfile Config API org.eclipse.microprofile.config:microprofile-config-api.

The dependency is defined as:

<dependency>
    <groupId>org.eclipse.microprofile.config</groupId>
    <artifactId>microprofile-config-api</artifactId>
    <scope>provided</scope>
</dependency>

It must be added to the <dependencies> of your pom.xml:

<dependencies>
    ...
    <!-- copy the dependency here -->
</dependencies>

Use the MicroProfile Config API

You can now use Eclipe MicroProfile Config in your application.

As an example, you can update the GettingStartedService.java file to configure the text that displays "Hello":

package org.wildfly.examples;

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.inject.Inject;
import org.eclipse.microprofile.config.inject.ConfigProperty;

@ApplicationScoped
public class GettingStartedService {

    @Inject
    @ConfigProperty(name = "hello.text", defaultValue = "Hello")
    String helloText;

    public String hello(String name) {
        return String.format(helloText + " '%s'.", name);
    }
}

In this example, you have annotated a helloText String with a ConfigProperty annotation.

You can now use the hello.text system property or the HELLO_TEXT environment variable to change the output of the hello method. The default value of the helloText is configured in the ConfigProperty annotation with the defaultValue attribute.

Once the GettingStartedService.java file is modified, you can repackage your application and restart it with the HELLO_TEXT environment variable set to Bonjour:

mvn clean package
HELLO_TEXT="Bonjour" ./target/server/bin/standalone.sh

If you now access the application at http://localhost:8080 and type World in the text field, it now returns Bonjour, World.

What’s next?

MicroProfile Config provides multiple options to read the configuration from various sources (System properties, environment variables, ConfigMaps and Secrets from Kubernetes), you can learn more by reading WildFly’s MicroProfile Config Subsystem Configuration Guide or reading the specification at Eclipse MicroProfile Config website.

References

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