Chapter 4. Developing and deploying Thorntail application

In addition to using an example, you can create new Thorntail applications from scratch and deploy them to OpenShift.

4.1. Creating an application from scratch

Creating a simple Thorntail–based application with a REST endpoint from scratch.

Prerequisites

  • OpenJDK 8 or OpenJDK 11 installed
  • Maven 3.5.0 installed

Procedure

  1. Create a directory for the application and navigate to it:

    $ mkdir myApp
    $ cd myApp

    We recommend you start tracking the directory contents with Git. For more information, see Git tutorial.

  2. In the directory, create a pom.xml file 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/maven-v4_0_0.xsd">
      <modelVersion>4.0.0</modelVersion>
    
      <groupId>com.example</groupId>
      <artifactId>restful-endpoint</artifactId>
      <version>1.0.0-SNAPSHOT</version>
      <packaging>war</packaging>
    
      <name>Thorntail Example</name>
    
      <properties>
        <version.thorntail>2.4.0.Final-redhat-00013</version.thorntail>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <failOnMissingWebXml>false</failOnMissingWebXml>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    
        <!-- 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>
      </properties>
    
      <dependencyManagement>
        <dependencies>
          <dependency>
            <groupId>io.thorntail</groupId>
            <artifactId>bom</artifactId>
            <version>${version.thorntail}</version>
            <scope>import</scope>
            <type>pom</type>
          </dependency>
        </dependencies>
      </dependencyManagement>
      <dependencies>
        <dependency>
          <groupId>io.thorntail</groupId>
          <artifactId>jaxrs</artifactId>
        </dependency>
      </dependencies>
    
      <build>
        <finalName>restful-endpoint</finalName>
        <plugins>
          <plugin>
            <groupId>io.thorntail</groupId>
            <artifactId>thorntail-maven-plugin</artifactId>
            <version>${version.thorntail}</version>
            <executions>
              <execution>
                <goals>
                  <goal>package</goal>
                </goals>
              </execution>
            </executions>
          </plugin>
        </plugins>
      </build>
    
      <!-- Specify the repositories containing RHOAR artifacts -->
      <repositories>
        <repository>
          <id>redhat-ga</id>
          <name>Red Hat GA Repository</name>
          <url>https://maven.repository.redhat.com/ga/</url>
        </repository>
      </repositories>
    
      <pluginRepositories>
        <pluginRepository>
          <id>redhat-ga</id>
          <name>Red Hat GA Repository</name>
          <url>https://maven.repository.redhat.com/ga/</url>
        </pluginRepository>
      </pluginRepositories>
    
    </project>
  3. Create a directory structure for your application:

    mkdir -p src/main/java/com/example/rest
  4. In the src/main/java/com/example/rest directory, create the source files:

    • HelloWorldEndpoint.java with the class that serves the HTTP endpoint:

      package com.example.rest;
      
      import javax.ws.rs.Path;
      import javax.ws.rs.core.Response;
      import javax.ws.rs.GET;
      import javax.ws.rs.Produces;
      
      @Path("/hello")
      public class HelloWorldEndpoint {
      
        @GET
        @Produces("text/plain")
        public Response doGet() {
          return Response.ok("Hello from Thorntail!").build();
        }
      }
    • RestApplication.java with the application context:

      package com.example.rest;
      
      import javax.ws.rs.core.Application;
      import javax.ws.rs.ApplicationPath;
      
      @ApplicationPath("/rest")
      public class RestApplication extends Application {
      }
  5. Execute the application using Maven:

    $ mvn thorntail:run

Results

Accessing the http://localhost:8080/rest/hello URL in your browser should return the following message:

Hello from Thorntail!

After finishing the procedure, there should be a directory on your hard drive with the following contents:

myApp
├── pom.xml
└── src
    └── main
        └── java
            └── com
                └── example
                    └── rest
                        ├── HelloWorldEndpoint.java
                        └── RestApplication.java

4.2. Deploying Thorntail application to OpenShift

To deploy your Thorntail 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 Thorntail application for OpenShift deployment

For deploying your Thorntail application to OpenShift, it must contain:

  • Launcher profile information in the application’s pom.xml file.

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:

    ...
    
    <profiles>
        <profile>
          <id>openshift</id>
          <build>
            <plugins>
              <plugin>
                <groupId>io.fabric8</groupId>
                <artifactId>fabric8-maven-plugin</artifactId>
                <version>4.1.0</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>

4.2.3. Deploying Thorntail application to OpenShift using Fabric8 Maven plugin

To deploy your Thorntail 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/rest/hello
      Hello from Thorntail!

4.3. Deploying Thorntail application to standalone Red Hat Enterprise Linux

To deploy your Thorntail application to standalone 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 Thorntail application for standalone Red Hat Enterprise Linux deployment

For deploying your Thorntail application to standalone 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.thorntail</groupId>
            <artifactId>thorntail-maven-plugin</artifactId>
            <version>${version.thorntail}</version>
            <executions>
              <execution>
                <goals>
                  <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 Thorntail application to standalone Red Hat Enterprise Linux using jar

To deploy your Thorntail application to standalone 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-thorntail.jar
  2. Verify the deployment.

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

    $ curl http://localhost:8080