docker-maven.adoc

Docker Maven Plugin

Maven plugin allows you to manage Docker images and containers from pom.xml. It comes with predefined goals:

Goal	Description
docker:start	Create and start containers
docker:stop	Stop and destroy containers
docker:build	Build images
docker:push	Push images to a registry
docker:remove	Remove images from local docker host
docker:logs	Show container logs

Run Java EE Application

1. Clone the workspace as:

   git clone https://github.com/javaee-samples/javaee7-docker-maven.git

2. Build the image as:

   mvn package -Pdocker

3. Verify the image as:

   docker images
   REPOSITORY                        TAG                 IMAGE ID            CREATED             VIRTUAL SIZE
   arungupta/javaee7-docker-maven    latest              2e51b3fca40f        4 seconds ago       581.5 MB

4. Run the container as:

   mvn install -Pdocker

5. Access your application at http://dockerhost:8080/javaee7-docker-maven/resources/persons. It shows the output as:

   curl http://dockerhost:8080/javaee7-docker-maven/resources/persons
   <?xml version="1.0" encoding="UTF-8" standalone="yes"?><collection><person><name>Penny</name></person><person><name>Leonard</name></person><person><name>Sheldon</name></person><person><name>Amy</name></person><person><name>Howard</name></person><person><name>Bernadette</name></person><person><name>Raj</name></person><person><name>Priya</name></person></collection>

Understand Plugin Configuration

pom.xml is updated to include docker-maven-plugin as:

<plugin>
    <groupId>org.jolokia</groupId>
    <artifactId>docker-maven-plugin</artifactId>
    <version>0.11.5</version>
    <configuration>
        <images>
            <image>
                <alias>user</alias>
                <name>arungupta/javaee7-docker-maven</name>
                <build>
                    <from>arungupta/wildfly:8.2</from>
                    <assembly>
                        <descriptor>assembly.xml</descriptor>
                        <basedir>/</basedir>
                    </assembly>
                    <ports>
                        <port>8080</port>
                    </ports>
                </build>
                <run>
                    <ports>
                        <port>8080:8080</port>
                    </ports>
                </run>
            </image>
        </images>
    </configuration>
    <executions>
        <execution>
            <id>docker:build</id>
            <phase>package</phase>
            <goals>
                <goal>build</goal>
            </goals>
        </execution>
        <execution>
            <id>docker:start</id>
            <phase>install</phase>
            <goals>
                <goal>start</goal>
            </goals>
        </execution>
    </executions>
</plugin>

Each image configuration has three parts:

1. Image name and alias

2. <build> that defines how the image is created. Base image, build artifacts and their dependencies, ports to be exposed, etc to be included in the image are specified here. Assembly descriptor format is used to specify the artifacts to be included and is defined in the src/main/docker directory.

   assembly.xml in our case looks like:

   <assembly . . .>
     <id>javaee7-docker-maven</id>
     <dependencySets>
       <dependencySet>
         <includes>
           <include>org.javaee7.sample:javaee7-docker-maven</include>
         </includes>
         <outputDirectory>/opt/jboss/wildfly/standalone/deployments/</outputDirectory>
         <outputFileNameMapping>javaee7-docker-maven.war</outputFileNameMapping>
       </dependencySet>
     </dependencySets>
   </assembly>

3. <run> that defines how the container is run. Ports that need to be exposed are specified here.

In addition, package phase is tied to docker:build goal and install phase is tied to docker:start goal.