Running a Spring Boot App with Docker

Step 1: install docker

I followed these instructions for Ubuntu 12.04.

In addition to that I also added my user to the 'docker' group.

 sudo usermod -a -G docker $USER

This allows the user to run docker without having to type 'sudo' each time.

For the rest of the steps I mostly followed as described here with some minor variations because I was using the 'New Spring Starter' wizard in STS which does some of the pom setup for us.

Step 2: create a boot app

In STS use the 'New Spring Starter' wizard to create a new web app (select the 'web' starter dependency in the wizard).

I called my app 'spring-boot-docker' and also changed the 'artifact-id' to 'spring-boot-docker'.

You can add some stuff to your app if you want (a hello world page). I was content with what boot generated... which is an webserver that only serves up 404 error pages.

Step 3: dockerify the app

Create a 'docker' folder at the root of your project.

Create a file 'docker/Dockerfile' and put this content in it:

  FROM dockerfile/java:oracle-java7
  ADD spring-boot-docker-0.0.1-SNAPSHOT.jar /opt/spring-boot-docker/
  EXPOSE 8080
  WORKDIR /opt/spring-boot-docker/
  CMD ["java", "-jar", "spring-boot-maven-docker.jar"]

Add this to the pom:

<plugin>
    <artifactId>maven-resources-plugin</artifactId>
    <executions>
        <execution>
            <id>copy-resources</id>
            <phase>validate</phase>
            <goals>
                <goal>copy-resources</goal>
            </goals>
            <configuration>
                <outputDirectory>${basedir}/target/</outputDirectory>
                <resources>
                    <resource>
                        <directory>docker</directory>
                        <filtering>true</filtering>
                    </resource>
                </resources>
            </configuration>
        </execution>
    </executions>
</plugin>

Step 4: Create docker image

First we need to build our stuff with maven. From the root of the project:

 mvn clean install

Then we can build the image

 cd target
 docker build -t spring-boot-docker .

Step 5: Run the image

Check that the image was create and determine its id:

 docker images

This shows you a list of images find the 'spring-boot-docker' one and write down its ID to use in the next command:

 docker run -p 8080:8080 9969adf59c45

You can now connect to http://localhost:8080/

Note: unless you actually added something to your app (like a hello world page) you'll get a 404 error page.