Dockerfile

Light-codegen generates a docker folder in the root of the target project, and this folder contains several Dockerfiles to build different Docker images.

For 1.6.x Java 8 branch, we have a default Dockerfile based on the Alpine image and Dockerfile-RedHat based on the RedHat image for some enterprise customers.

When we move to Java 11, we have added several more Dockerfiles.

Dockerfile

FROM openjdk:11.0.3-slim
ADD /target/light-router.jar server.jar
CMD ["/bin/sh","-c","java -Dlight-4j-config-dir=/config -Dlogback.configurationFile=/config/logback.xml -jar /server.jar"]

It is the default Dockerfile based on openjdk:11.0.3-slim. It is several hundreds of MB in size but it is official image.

Dockerfile-Debug

FROM openjdk:11.0.3-slim
ADD /target/light-router.jar server.jar
CMD ["/bin/sh","-c","java -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005 -Dlight-4j-config-dir=/config -Dlogback.configurationFile=/config/logback.xml -jar /server.jar"]

This is very similar to the default one with agentlib:jdwp added to the command line. It supports the remote debugging from the IDE.

Dockerfile-RedHat

We still want to support RedHat JDK 11 but currently, we only have a placeholder here.

Dockerfile-Zulu

FROM azul/zulu-openjdk-alpine:11 as packager

RUN { \
        java --version ; \
        echo "jlink version:" && \
        jlink --version ; \
    }

ENV JAVA_MINIMAL=/opt/jre

# build modules distribution
RUN jlink \
    --verbose \
    --add-modules \
        java.base,java.sql,java.naming,java.desktop,java.xml,jdk.crypto.cryptoki \
    --compress 2 \
    --strip-debug \
    --no-header-files \
    --no-man-pages \
    --output "$JAVA_MINIMAL"

# Second stage, add only our minimal "JRE" distr and our app
FROM alpine

ENV JAVA_MINIMAL=/opt/jre
ENV PATH="$PATH:$JAVA_MINIMAL/bin"

COPY --from=packager "$JAVA_MINIMAL" "$JAVA_MINIMAL"
COPY /target/light-router.jar server.jar
CMD ["/bin/sh","-c","java -Dlight-4j-config-dir=/config -Dlogback.configurationFile=/config/logback.xml -jar /server.jar"]

This is the smallest image, and the final size for the light-router is just about 75MB. It is based on the Alpine Linux and uses Jlink to include only the modules that light-4j needs.