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Dockerized Java EE 8 applications with GlassFish 5.0

#javaee #docker saturday, october 21, 2017

GlassFish 5.0 represents the reference implementation of Java EE 8. We can dockerize Java EE 8 applications by using a GlassFish base image, such as the official oracle/glassfish.

The Dockerfile of a zero-dependency Java EE 8 application looks like follows:

FROM oracle/glassfish:5.0

COPY target/application.war $GLASSFISH_HOME/glassfish/domains/domain1/autodeploy/

A Docker container of that image starts the application server and auto-deploys our application.

application.war is packaged a thin WAR deployment artifact, what speeds up build, publishing and deployment times. The WAR file comprises only application-specific classes, no implementation-specific JAR files. If needed, any dependencies are added on top of the base image — before the actual application.

Imagine, we want to add the Prometheus Java API:

FROM oracle/glassfish:5.0

ENV GLASSFISH_LIB=$GLASSFISH_HOME/glassfish/domains/domain1/lib/ext/

# add Prometheus Java API
COPY .../simpleclient-0.0.26.jar $GLASSFISH_LIB
COPY .../simpleclient_common-0.0.26.jar $GLASSFISH_LIB

COPY target/application.war $GLASSFISH_HOME/glassfish/domains/domain1/autodeploy/

The application can already use Java EE 8 standards such as JSON-B. The provided dependency is javax:javaee-api:8.0 — same as the Java EE 7 API with incremented version number.

To see a full example that uses Prometheus, please see Prometheus with Java EE. That example can also run on Java EE 8 and GlassFish 5 by updating the API version to 8.0 and the Docker base image to oracle/glassfish.

Have fun developing Java EE 8 applications for Docker!


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