Run the Micronaut application on a random port

Use the following application configuration to run the Micronaut application on a random port.

micronaut:
  server:
    port: -1

 

Find the below working application.

 

Step 1: Create new maven project ‘micronaut-rest-random-port’.

 

Step 2: Update pom.xml with maven dependencies.

 

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.sample.app</groupId>
    <artifactId>micronaut-rest-random-port</artifactId>
    <version>0.1</version>
    <packaging>jar</packaging>

    <parent>
        <groupId>io.micronaut</groupId>
        <artifactId>micronaut-parent</artifactId>
        <version>3.7.4</version>
    </parent>

    <properties>
        <packaging>jar</packaging>
        <jdk.version>11</jdk.version>
        <release.version>11</release.version>
        <micronaut.version>3.7.3</micronaut.version>
        <micronaut.runtime>netty</micronaut.runtime>
        <exec.mainClass>com.sample.app.App</exec.mainClass>
    </properties>

    <repositories>
        <repository>
            <id>central</id>
            <url>https://repo.maven.apache.org/maven2</url>
        </repository>
    </repositories>

    <dependencies>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-inject</artifactId>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-validation</artifactId>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-http-client</artifactId>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-http-server-netty</artifactId>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>io.micronaut</groupId>
            <artifactId>micronaut-jackson-databind</artifactId>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>jakarta.annotation</groupId>
            <artifactId>jakarta.annotation-api</artifactId>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>ch.qos.logback</groupId>
            <artifactId>logback-classic</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>io.micronaut.test</groupId>
            <artifactId>micronaut-test-junit5</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-api</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-engine</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>io.micronaut.build</groupId>
                <artifactId>micronaut-maven-plugin</artifactId>
            </plugin>

            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <!-- Uncomment to enable incremental compilation -->
                    <!-- <useIncrementalCompilation>false</useIncrementalCompilation> -->

                    <annotationProcessorPaths
                        combine.children="append">
                        <path>
                            <groupId>io.micronaut</groupId>
                            <artifactId>micronaut-http-validation</artifactId>
                            <version>${micronaut.version}</version>
                        </path>
                    </annotationProcessorPaths>

                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

 

Step 3: Create application.yml file under src/main/resources folder.

 

application.yml

micronaut:
  server:
    port: -1

 

Step 4: Define AppEventListeners class.

 

AppEventListeners.java

package com.sample.app.listeners;

import io.micronaut.runtime.event.annotation.EventListener;
import io.micronaut.runtime.server.EmbeddedServer;
import io.micronaut.runtime.server.event.ServerStartupEvent;
import jakarta.inject.Inject;
import jakarta.inject.Singleton;

@Singleton
public class AppEventListeners {

    @Inject
    EmbeddedServer embeddedServer;

    @EventListener
    public void onStartup(ServerStartupEvent event) {
        System.out.println("host : " + embeddedServer.getHost());
        System.out.println("port : " + embeddedServer.getPort());
    }
}

Above class print the server host and port details.

 

Step 5: Define main application class.

 

App.java

package com.sample.app;

import io.micronaut.runtime.Micronaut;

public class App {

    public static void main(String[] args) {
        Micronaut.run(App.class);
    }
}

Total project structure looks like below.

Build the project using mvn package command.

Navigate to the folder where pom.xml is located and execute the command ‘mvn package’.

 

Upon command successful execution, you can see the jar file ‘micronaut-rest-random-port-0.1.jar’ in project target folder.

 

$ls ./target    
classes
generated-sources
generated-test-sources
maven-archiver
maven-status
micronaut-rest-random-port-0.1.jar
original-micronaut-rest-random-port-0.1.jar
test-classes

 

Execute below command to run the application.

java -jar ./target/micronaut-rest-random-port-0.1.jar

 

You will see host and port details in the console log.

host : localhost
port : 57205
16:54:38.696 [main] INFO io.micronaut.runtime.Micronaut - Startup completed in 676ms. Server Running: http://localhost:57205

 

You can download this application from this link.

 

 

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