Chapter 4. Developing and deploying Eclipse Vert.x runtime application

In addition to using an example, you can create a new Eclipse Vert.x application from scratch and deploy it to OpenShift or stand-alone Red Hat Enterprise Linux.

4.1. Developing Eclipse Vert.x application

For a basic Eclipse Vert.x application, you need to create the following:

  • A Java class containing Eclipse Vert.x methods.
  • A pom.xml file containing information required by Maven to build the application.

The following procedure creates a simple Greeting application that returns "Greetings!" as response.

Prerequisites

  • Maven installed.
  • OpenJDK 8 or OpenJDK 11 installed.

Procedure

  1. Create a new directory myApp, and navigate to it. 

    $ mkdir myApp
$ cd myApp

    This is the root directory for the application.

  2. Create directory structure src/main/java/com/example/ in the root directory, and navigate to it. 

    $ mkdir -p src/main/java/com/example/
$ cd src/main/java/com/example/

  3. Create a Java class file MyApp.java containing the application code. 

    package com.example;

import io.vertx.core.AbstractVerticle;
import io.vertx.core.Future;

public class MyApp extends AbstractVerticle {

    @Override
    public void start(Future<Void> fut) {
        vertx
            .createHttpServer()
            .requestHandler(r ->
                r.response().end("Greetings!"))
            .listen(8080, result -> {
                if (result.succeeded()) {
                    fut.complete();
                } else {
                    fut.fail(result.cause());
                }
            });
    }
}

  4. Create a pom.xml file in the application root directory myApp with the following content: 

    <?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.example</groupId>
  <artifactId>my-app</artifactId>
  <version>1.0.0-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>My Application</name>
  <description>Example application using Vert.x</description>

  <properties>
    <vertx.version>3.8.5.redhat-00005</vertx.version>
    <vertx-maven-plugin.version>1.0.20</vertx-maven-plugin.version>
    <vertx.verticle>com.example.MyApp</vertx.verticle>

    <!-- Specify the JDK builder image used to build your application. -->
    <fabric8.generator.from>registry.access.redhat.com/redhat-openjdk-18/openjdk18-openshift:latest</fabric8.generator.from>

    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
  </properties>

  <!-- Import dependencies from the Vert.x BOM. -->
  <dependencyManagement>
    <dependencies>
      <dependency>
        <groupId>io.vertx</groupId>
        <artifactId>vertx-dependencies</artifactId>
        <version>${vertx.version}</version>
        <type>pom</type>
        <scope>import</scope>
      </dependency>
    </dependencies>
  </dependencyManagement>

  <!-- Specify the Vert.x artifacts that your application depends on. -->
  <dependencies>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-core</artifactId>
    </dependency>
    <dependency>
      <groupId>io.vertx</groupId>
      <artifactId>vertx-web</artifactId>
    </dependency>
  </dependencies>

  <!-- Specify the repositories containing Vert.x artifacts. -->
  <repositories>
    <repository>
      <id>redhat-ga</id>
      <name>Red Hat GA Repository</name>
      <url>https://maven.repository.redhat.com/ga/</url>
    </repository>
  </repositories>

  <!-- Specify the repositories containing the plugins used to execute the build of your application. -->
  <pluginRepositories>
    <pluginRepository>
      <id>redhat-ga</id>
      <name>Red Hat GA Repository</name>
      <url>https://maven.repository.redhat.com/ga/</url>
    </pluginRepository>
  </pluginRepositories>

  <!-- Configure your application to be packaged using the Vert.x Maven Plugin. -->
  <build>
    <plugins>
      <plugin>
        <groupId>io.reactiverse</groupId>
        <artifactId>vertx-maven-plugin</artifactId>
        <version>${vertx-maven-plugin.version}</version>
        <executions>
          <execution>
            <id>vmp</id>
            <goals>
              <goal>initialize</goal>
              <goal>package</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

  5. Build the application using Maven from the root directory of the application. 

    $ mvn vertx:run

  6. Verify that the application is running.

    Using curl or your browser, verify your application is running at http://localhost:8080. 

    $ curl http://localhost:8080
Greetings!

Additional information

  • As a recommended practice, you can configure liveness and readiness probes to enable health monitoring for your application when running on OpenShift. To learn how application health monitoring on OpenShift works, try the Health Check example.

4.2. Deploying Eclipse Vert.x application to OpenShift

To deploy your Eclipse Vert.x application to OpenShift, configure the pom.xml file in your application and then use the Fabric8 Maven plugin. You can specify an OpenJDK image by replacing the fabric8.generator.from URL in the pom.xml file.

4.2.1. OpenJDK images for Red Hat Enterprise Linux

You can select the OpenJDK image used to build and deploy your application to OpenShift. OpenJDK images are available for RHEL 7 and RHEL 8 with OpenJDK 8 or OpenJDK 11.

Docker or podman authentication into the Red Hat Container Catalog is required to access RHEL 8 images. The authentication procedures are provided in the Red Hat Container Catalog links in the following table.

OSJDKRed Hat Container Catalog

RHEL 7

OpenJDK 8

RHEL 7 with OpenJDK 8

RHEL 7

OpenJDK 11

RHEL 7 with OpenJDK 11

RHEL 8

OpenJDK 8

RHEL 8 with OpenJDK 8

RHEL 8

OpenJDK 11

RHEL 8 with OpenJDK 11

Note

The use of a RHEL 8-based container on a RHEL 7 host, for example with OpenShift 3 or OpenShift 4, has limited support. For more information, see the Red Hat Enterprise Linux Container Compatibility Matrix.

4.2.2. Preparing Eclipse Vert.x application for OpenShift deployment

For deploying your Eclipse Vert.x application to OpenShift, it must contain:

  • Launcher profile information in the application’s pom.xml file.
  • A deployment yaml file containing environment details.

In the following procedure, a profile with Fabric8 Maven plugin is used for building and deploying the application to OpenShift.

Prerequisites

Procedure

  1. Add the following content to the pom.xml file in the application root directory: 

    <!-- Specify the JDK builder image used to build your application. -->
<properties>
  <fabric8.generator.from>registry.access.redhat.com/redhat-openjdk-18/openjdk18-openshift:latest</fabric8.generator.from>
</properties>

...

<profiles>
    <profile>
      <id>openshift</id>
      <build>
        <plugins>
          <plugin>
            <groupId>io.fabric8</groupId>
            <artifactId>fabric8-maven-plugin</artifactId>
            <version>4.3.0</version>
            <executions>
              <execution>
                <goals>
                  <goal>resource</goal>
                  <goal>build</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
        </plugins>
      </build>
    </profile>
</profiles>

  2. Replace the fabric8.generator.from property in the pom.xml file to specify OpenJDK image.

    • RHEL 7 with OpenJDK 8 

      <fabric8.generator.from>registry.access.redhat.com/redhat-openjdk-18/openjdk18-openshift:latest</fabric8.generator.from>

    • RHEL 7 with OpenJDK 11 

      <fabric8.generator.from>registry.access.redhat.com/openjdk/openjdk-11-rhel7:latest</fabric8.generator.from>

    • RHEL 8 with OpenJDK 8 

      <fabric8.generator.from>registry.redhat.io/openjdk/openjdk-8-rhel8:latest</fabric8.generator.from>

    • RHEL 8 with OpenJDK 11 

      <fabric8.generator.from>registry.redhat.io/openjdk/openjdk-11-rhel8:latest</fabric8.generator.from>

  3. Create deployment.yaml file in src/main/fabric8 directory with the following content: 

    spec:
  template:
    spec:
      containers:
        - name: vertx
          env:
            - name: KUBERNETES_NAMESPACE
              valueFrom:
                fieldRef:
                  apiVersion: v1
                  fieldPath: metadata.namespace
            - name: JAVA_OPTIONS
              value: '-Dvertx.cacheDirBase=/tmp -Dvertx.jgroups.config=default'

4.2.3. Deploying Eclipse Vert.x application to OpenShift using Fabric8 Maven plugin

To deploy your Eclipse Vert.x application to OpenShift, you must perform the following:

  • Log in to your OpenShift instance.
  • Deploy the application to the OpenShift instance.

Prerequisites

  • oc CLI client installed.
  • Maven installed.

Procedure

  1. Log in to your OpenShift instance with the oc client. 

    $ oc login ...

  2. Create a new project in the OpenShift instance. 

    $ oc new-project MY_PROJECT_NAME

  3. Deploy the application to OpenShift using Maven from the application’s root directory. The root directory of an application contains the pom.xml file. 

    $ mvn clean fabric8:deploy -Popenshift

    This command uses the Fabric8 Maven Plugin to launch the S2I process on OpenShift and start the pod.

  4. Verify the deployment.

    1. Check the status of your application and ensure your pod is running. 

      $ oc get pods -w
NAME                             READY     STATUS      RESTARTS   AGE
MY_APP_NAME-1-aaaaa               1/1       Running     0          58s
MY_APP_NAME-s2i-1-build           0/1       Completed   0          2m

      The MY_APP_NAME-1-aaaaa pod should have a status of Running once it is fully deployed and started.

      Your specific pod name will vary.

    2. Determine the route for the pod.

      Example Route Information

      $ oc get routes
NAME                 HOST/PORT                                                     PATH      SERVICES        PORT      TERMINATION
MY_APP_NAME         MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME      MY_APP_NAME      8080

      The route information of a pod gives you the base URL which you use to access it.

      In this example, http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME is the base URL to access the application.

    3. Verify that your application is running in OpenShift. 

      $ curl http://MY_APP_NAME-MY_PROJECT_NAME.OPENSHIFT_HOSTNAME
Greetings!

4.3. Deploying Eclipse Vert.x application to stand-alone Red Hat Enterprise Linux

To deploy your Eclipse Vert.x application to stand-alone Red Hat Enterprise Linux, configure the pom.xml file in the application, package it using Maven and deploy using the java -jar command.

Prerequisites

  • RHEL 7 or RHEL 8 installed.

4.3.1. Preparing Eclipse Vert.x application for stand-alone Red Hat Enterprise Linux deployment

For deploying your Eclipse Vert.x application to stand-alone Red Hat Enterprise Linux, you must first package the application using Maven.

Prerequisites

  • Maven installed.

Procedure

  1. Add the following content to the pom.xml file in the application’s root directory: 

      ...
  <build>
    <plugins>
      <plugin>
        <groupId>io.reactiverse</groupId>
        <artifactId>vertx-maven-plugin</artifactId>
        <version>${vertx-maven-plugin.version}</version>
        <executions>
          <execution>
            <id>vmp</id>
            <goals>
              <goal>initialize</goal>
              <goal>package</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
  ...

  2. Package your application using Maven. 

    $ mvn clean package

    The resulting JAR file is in the target directory.

4.3.2. Deploying Eclipse Vert.x application to stand-alone Red Hat Enterprise Linux using jar

To deploy your Eclipse Vert.x application to stand-alone Red Hat Enterprise Linux, use java -jar command.

Prerequisites

  • RHEL 7 or RHEL 8 installed.
  • OpenJDK 8 or OpenJDK 11 installed.
  • A JAR file with the application.

Procedure

  1. Deploy the JAR file with the application. 

    $ java -jar my-app-fat.jar

  2. Verify the deployment.

    Use curl or your browser to verify your application is running at http://localhost:8080: 

    $ curl http://localhost:8080