Instructions

In order to use a Spring Boot project which is packaged as a WAR and which contains by example JSP pages, JSP Standard Tag Library (JSTL), ... some modifications are required to build/deploy correctly the project as a container on OpenShift or Kubernetes platform.

The modifications described hereafter assume that you use the Fabric8 Maven Plugin like also the Spring Boot Maven Plugin

• Enable the repackaging of the WAR to include the Spring Boot classes used to launch the application and to update the MANIFEST.mf file definition with the following properties :

  • Main-Class: org.springframework.boot.loader.WarLauncher
  • Spring-Boot-Classes: WEB-INF/classes/
  • Spring-Boot-Lib: WEB-INF/lib/
  • Spring-Boot-Version: 1.5.8.RELEASE

  Set this option using the goal repackage of the Spring Boot maven plugin. See the xml tag <execution><execution><goals><goal>repackage</goal> defined under the Spring Boot maven plugin

• Add an env var <ARTIFACT_COPY_ARGS>*.war</ARTIFACT_COPY_ARGS> to specify during the creation of the Docker image to copy the war file instead of the uber jar which is the by default option when a Microservice is created. This en var will be used by OpenShift during the S2I Build Process with the war binary content pushed.

  Such information should be defined using the Fabric8 Maven Plugin by adding within the <configuration> xml tag, the definition of the Docker image to be created with the env var.

     <configuration>
         <images>
             <image>
                 <name>${project.artifactId}:%t</name>
                 <alias>spring-boot-mvc-jsp</alias>
                 <build>
                     <from>redhat-openjdk-18/openjdk18-openshift</from>
                     <assembly>
                         <basedir>/deployments</basedir>
                         <descriptorRef>artifact</descriptorRef>
                     </assembly>
                     <env>
                         <ARTIFACT_COPY_ARGS>*.war</ARTIFACT_COPY_ARGS>
                         <JAVA_APP_DIR>/deployments</JAVA_APP_DIR>
                     </env>
                     <ports>
                         <port>8080</port>
                     </ports>
                 </build>
             </image>
         </images>
     </configuration> 

• Define next, an env var JAVA_APP_JAR=mvc-jsp-0.0.1-SNAPSHOT.war for the DeploymentConfig file to specify to use the war included within the Docker image as the Java application to be launched.

  This modification can be done by specifying an env var within the DeploymentConfig resource under the specification of the container to be created. The parameter will be used by OpenShift when it will create the pod and the linux container defined. The env var must be specified within the src/main/fabric8/deployment.yml file that the Fabric8 Maven Plugin will use.

    spec:
      template:
        spec:
          containers:
          - env:
            - name: JAVA_APP_JAR
              value: ${project.artifactId}-${project.version}.war

Deploy project

mvn clean fabric8:deploy -Popenshift