java

NAIS Java baseimage

Basic Usage

We support three (four) ways of running your app:

1. A fat jar called app.jar
2. An exploded/layered spring-boot jar
3. An exploded war
4. Custom run script

Create a Dockerfile containing:

Simplest example

The simplest way of running your app is to create a far jar and copy it into your container as app.jar. Since the default working directory is /app, there's no need to specify the path.

FROM ghcr.io/navikt/baseimages/temurin:<version>
COPY target/my-awesome.jar app.jar

If you want to use another name for your file, set it using APP_JAR:

FROM ghcr.io/navikt/baseimages/temurin:<version>
ENV APP_JAR=my-awesome.jar
COPY target/my-awesome.jar .

Using exploded/layered Spring-Boot JAR

See the Spring Boot documentation for more information. Example provided below for NAV.

FROM eclipse-temurin:<java-version>-jre as builder

WORKDIR application
COPY target/my-awesome.jar app.jar

# Extract layers
RUN java -Djarmode=layertools -jar app.jar extract

FROM ghcr.io/navikt/baseimages/temurin:<java-version>

# Copy extracted layers into container
COPY --from=builder --chown=apprunner:apprunner application/dependencies/ ./
COPY --from=builder --chown=apprunner:apprunner application/spring-boot-loader/ ./
COPY --from=builder --chown=apprunner:apprunner application/snapshot-dependencies/ ./
COPY --from=builder --chown=apprunner:apprunner application/application/ ./

Using exploded WAR?

Supply the name of your main class as an environment variable called MAIN_CLASS if the name of your main class is not the default "Main".

Customisation

Custom runtime options may be specified using the environment variable JAVA_OPTS.

Start up scripts

You can add custom behavior to your container by copying .sh files to the /init-scripts dir. The files are sourced which means that you can export environment variables or extend the existing ones like JAVA_OPTS.

Run script

If none of the other ways of running an app suits you, you can create a custom run-script at /run-java.sh. Be sure to include the different environment variables JAVA_OPTS, DEFAULT_JVM_OPTS and RUNTIME_OPTS to get all the goodies that the baseimage sets up for you.

# copy into the container as /run-java.sh
exec java ${DEFAULT_JVM_OPTS} ${JAVA_OPTS} -jar app.jar ${RUNTIME_OPTS} $@

We highly recommend that you write your app so that you don't need this feature.