Using Azul Zulu JRE with Docker Lucee

Azul Zulu is a smaller JRE than the OPENJDK one so this is one way to reduce our docker file size

Posted by Mark Drew on July 26, 2022

Tagged under lucee,jre,azul,zulu,docker

In our previous posts about building a lucee docker image and adding a password we got our image down to a comfortable 239MB

In the cfml slack, Brad Wood mentioned that are other projects to bring down the size of Lucee, such as Pete Freitag’s Minibox which comes in at about 78 Mb! Great work!

These series of posts are really not to compete with that. They are serving to document some practices and methods I use as well as to do some investigations that can fit in other development pipelines I am using.

In that conversation, Brad also mentioned Azul Zulu JDK. Which turns out to be only about 40MB! Let’s give THAT a spin and see if everything works as expected!

As previously mentioned we only need the JRE so that is what I downloaded into our image:

FROM alpine as base
#Install zulu JRE
ADD zulu_jre.tar.gz
RUN tar -xzvf zulu_jre.tar.gz
RUN mv zulu18.32.11-ca-jre18.0.2-linux_musl_aarch64 zulu_jre
ENV PATH=/zulu_jre/bin:$PATH
#Set lucee version
# Download Lucee
ADD${LUCEE_VERSION}.jar lucee-light.jar
RUN mkdir /lucee && \
     unzip -d /lucee && \
     chmod +x /lucee/*.sh && \
     chmod +x /lucee/bin/*.sh && \
     rm -f && \
     rm -rf /lucee/__MACOSX && \
     mv lucee-light.jar /lucee/lib/ext/lucee.jar && \
     mkdir -p /lucee/lucee-server/context/ && \
     mkdir -p /lucee/lucee-server/deploy/
RUN echo ${LUCEE_PASSWORD} > /lucee/lucee-server/context/password.txt 
# Add the admin extension
ADD /lucee/lucee-server/deploy/lucee.admin.extension-
COPY webroot /lucee/webapps/ROOT

FROM alpine as final
COPY --from=base /lucee /lucee
COPY --from=base /zulu_jre /zulu_jre
ENV PATH=/zulu_jre/bin:$PATH
ENTRYPOINT [ "/lucee/" ]

As usual, we are using our alpine base, but now ADDing the Azul Zulu JRE and naming it zulu_jre.tar.gz .

We then unzip it and move it to a folder called zulu_jre, finally, we add it to the Path so we can just call java from anywhere via ENV PATH=/zulu_jre/bin:$PATH

Once done we can do the usual thing we are doing with lucee, and download lucee light, our admin extension and warm up the server by doing RUN LUCEE_ENABLE_WARMUP=true /lucee/

That is our JRE and lucee prepared. Now we create our final image: FROM alpine as final Copy both the JRE and Lucee:

COPY --from=base /lucee /lucee
COPY --from=base /zulu_jre /zulu_jre

And add the jre/bin path to the PATH variable via ENV PATH=/zulu_jre/bin:$PATH

And that is it! Once we build this our image has gone down to 184MB! That gives us some room to breathe huh?

I will say I haven’t run a suite of tests on this JRE so I can’t confirm (nor deny!) if it all works as intended but we shall see. It’s always good to add monitoring and telemetry to your docker apps anyway (a topic for a future post I am sure).

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