malincrist / docker-java-hello-world Goto Github PK

This project provides a simple example of using Docker containers to build and run a Java application without installing Java. The sample is referenced in the DZone article Containers are the new Build Artifact.

This sample does not use the Smartsheet API.

When building a Java application we need a Java Development Kit (JDK). We can use an existing Docker image with a JDK in it to build our class.

docker run -it -v $(pwd):/build openjdk:8u131-jdk-alpine javac /build/HelloWorld.java

We can then take our Java class file (aka our build artifact) and bundle it into a container image.

docker build -t hello-world:8u131 -f Dockerfile-8u131 .

Once we have a compiled Java class we can simply execute it with a Java Runtime Environment (JRE).

docker run -it --rm=true hello-world:8u131

Let's assume we also want to run our Java class in a Java 9 environment to test it. We can easily take the same artifact (our HelloWorld.class file) that was compiled with Java 8u131 and run it in a Java 9 container. We use a different Dockerfile which specifies the Java 9 JVM as the base image. Then we build it and tag it so we have both the Java 8 and Java 9 images to run either.

docker build -t hello-world:9b170 -f Dockerfile-9b170 .
docker run -it --rm=true hello-world:9b170