Run a WildFly Application with JBang in Minutes

Why run WildFly from a Java script?

WildFly provides a standard API set for Java applications. Integrating it with JBang lets you prototype enterprise‑grade microservices quickly without creating a full project or managing server configuration, because all setup is expressed via JBang annotations.

Prerequisites

Install JBang ("JBang: Create Java scripts like a pro").

(Optional) Install WildFly Glow for advanced script control.

Basic example

The WildFly Glow documentation offers a minimal script that defines a Jakarta REST service:

///usr/bin/env jbang "$0" "$@" ; exit $?
//JAVA 17+
//DEPS org.wildfly.bom:wildfly-expansion:${wildfly.version:35.0.1.Final}@pom
//DEPS org.wildfly.glow:wildfly-glow:1.4.1.Final
//DEPS jakarta.ws.rs:jakarta.ws.rs-api
//DEPS jakarta.enterprise:jakarta.enterprise.cdi-api

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.ws.rs.GET;
import jakarta.ws.rs.Path;
import jakarta.ws.rs.ApplicationPath;
import jakarta.ws.rs.core.Application;

@ApplicationPath("/")
public class myapp extends Application {
    @Path("/hello")
    @ApplicationScoped
    public static class Hello {
        @GET
        public String sayHello() {
            return "Hello, WildFly!";
        }
    }
}

Run the script with jbang myapp.java. JBang resolves the dependencies, starts WildFly, and you can test the endpoint with curl http://localhost:8080/myapp/hello, which returns Hello, WildFly!.

Extending the default WildFly installation

WildFly Glow can list available add‑ons: ./wildfly-glow show-add-ons The output includes add‑ons for clustering, databases, Kafka, etc. To include Kafka, add the annotation //GLOW --add-ons=kafka.

Revisiting the basic example with Kafka

The script below adds Kafka support and uses MicroProfile Config to inject a configurable name:

///usr/bin/env jbang "$0" "$@" ; exit $?
//JAVA 17+
//DEPS org.wildfly.bom:wildfly-expansion:${wildfly.version:35.0.1.Final}@pom
//DEPS org.wildfly.glow:wildfly-glow:1.4.1.Final
//DEPS jakarta.ws.rs:jakarta.ws.rs-api
//DEPS jakarta.enterprise:jakarta.enterprise.cdi-api
//DEPS org.eclipse.microprofile.config:microprofile-config-api
//DEPS org.apache.kafka:kafka-clients:3.6.0
//GLOW --add-ons=kafka

import jakarta.enterprise.context.ApplicationScoped;
import jakarta.inject.Inject;
import jakarta.ws.rs.*;
import jakarta.ws.rs.core.Application;
import java.util.Properties;
import org.eclipse.microprofile.config.inject.ConfigProperty;
import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;

@ApplicationPath("/")
public class myapp extends Application {
    @Path("/hello")
    @ApplicationScoped
    public static class Hello {
        @Inject
        @ConfigProperty(name = "nick.name", defaultValue = "WildFly")
        private String configName;

        @GET
        @Path("/{name}")
        public String sayHelloWithParam(@PathParam("name") String name) {
            return sendMessage(name);
        }

        @GET
        public String sayHelloDefault() {
            return sendMessage(configName);
        }

        private String sendMessage(String nameToUse) {
            String message = String.format("Hello, %s!", nameToUse);
            Properties props = new Properties();
            props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
            props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
            props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
            try (KafkaProducer<String, String> producer = new KafkaProducer<>(props)) {
                producer.send(new ProducerRecord<>("greetings", "key", message));
            } catch (Exception e) {
                return "Failed to send message to Kafka: " + e.getMessage();
            }
            return message;
        }
    }
}

Before running the app, start a Kafka broker, e.g. with Docker: docker run -p 9092:9092 apache/kafka:4.0.0 Run the script again ( jbang myapp.java) and test the endpoints: curl http://localhost:8080/myapp/hello returns the default greeting; curl http://localhost:8080/myapp/hello/Frank returns a personalized greeting and sends the message to the Kafka topic greetings. To view messages, use the Kafka console consumer:

/opt/kafka/bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic greetings --from-beginning

Conclusion

The combination of WildFly, JBang, and WildFly Glow lets you embed a full Java EE application server in a single script, enabling rapid development, testing, and prototyping of enterprise features such as Kafka integration without a traditional project structure.