jeperez / petclinic-docker-jrebel

A demonstration of JRebel for updating the Java application running in a Docker container

Spring PetClinic Sample Application

This repo is a fork of the spring-petclinic/spring-framework-petclinic. The intent of the repository is to demonstrate, how to use JRebel to hot reload Java classes in a web application that is started in a Docker container.

The extra artifacts that are added compared to the original repositories:

• jrebel/ -- JRebel standalone distribution
• docker-compose.yml -- Docker Compose configuration that describes all the dependencies and configuration to start the application in the Docker container
• src/main/resources/rebel-remote.xml -- A configuration file for JRebel Remoting to recognize the module as "reloadable"

docker-compose.yml

The configuration file describes the environment and dependencies that are required for this example.

petclinic:
  image: tomcat:8.0
  ports:
    - "8080:8080"
  volumes:
    - "./jrebel/jrebel.jar:/jrebel.jar"
    - "./jrebel/lib/libjrebel64.so:/libjrebel64.so"
    - "./target/petclinic.war:/usr/local/tomcat/webapps/petclinic.war"
    - "~/.jrebel:/.jrebel"
 environment:
    - "JAVA_OPTS=-agentpath:/libjrebel64.so -Drebel.remoting_plugin=true"

The configuration uses Tomcat Docker image, hence the web archive of the application should be mapped to /usr/local/tomcat/webapps/ folder. The binaries from JRebel distribution -- jrebel.jar and libjrebel64.so -- are required for the agent to work. The local .jrebel is optional, but suggested to persist JRebel caches in order to make the application startup faster in case of restarts.

For more imformation about JRebel Remoting see the official documentation: https://manuals.zeroturnaround.com/jrebel/remoteserver/index.html

Running the application

!!!Before you start - make sure that Docker is installed on your machine!!!

      git clone --depth 1 https://github.com/antonarhipov/petclinic-docker-jrebel.git
      cd petclinic-docker-jrebel
      ./mvnw -DskipTests clean package
      docker-compose up

To start updating the application:

• Import the Maven project into your IDE of choice
• Generate rebel.xml configuration file
• Configure the remote server URL in JRebel settings. In this case, the URL is http://localhost:8080. (The IDE plugin will show a warning -- safely ignore)
• Make changes to the source code and synchronize the project via JRebel IDE plugin