This S2I example is intentionally NOT using Spring Boot, Vert.x, Dropwizard, Wildfly Swarm or whatever other simple "fat JAR" (non-WAR/EAR) Java server framework, but for clarity simply uses the simplest possible Java server application with a main() class. You can easily apply this example to whatever standalone Java application you want to container-ize with S2I. (We're using the Java built-in com.sun.net.httpserver.HttpServer; JUST for illustration of S2I.)

For local building, install s2i either from source https://github.com/openshift/source-to-image/releases/ or e.g. via:

sudo dnf install source-to-image

s2i build https://github.com/kubesphere/s2i-java-container --context-dir=java/examples/maven/ kubespheredev/java-8-centos7 s2i-java-maven-example

NB The --copy ensures that the latest content of the current directory and not only it's commited .git content is used (see S2I #418).

Now run it like this:

docker run -p 8080:8080 s2i-java-example

and see "hello, world" when accessing http://localhost:8080 - it works!

All JVM options documented on https://github.com/kubesphere/s2i-java-container/tree/master/java/images/centos are typically specified in .s2i/environment, but for quick testing can obviously also be specified on the docker run CLI like so:

docker run -e "JAVA_MAIN_CLASS=io.kubesphere.devops.s2i.example.Server" -p 8080:8080 s2i-java-example

• Why isn't it incremental? Keeps re-downloading Maven basics, every time..
• Support Gradle!
• Monitoring..
• Sources should not be runtime container?!

• https://github.com/kubesphere/s2i-java-container
• https://github.com/kubesphere/s2i-java-container/tree/master/java/images/centos
• https://github.com/kubesphere/s2ioperator