Spring boot plugin docker OCI image and JasperReports

Question

we are trying to switch the building of our Docker container to benefit from the OCI images generated by the spring boot gradle plugin.

As of now, we use the classic method: we have our own Dockerfile where all the customizing is done - including installing the necessary packages.

Using the gradle plugin as described here: https://docs.spring.io/spring-boot/docs/current/gradle-plugin/reference/htmlsingle/#build-image works quite well and almost everything is functional.

But we rely on JasperReports, and when we try to generate PDF, following error is thrown: java.lang.NullPointerException: Cannot load from short array because "sun.awt.FontConfiguration.head" is null. This is the reason why we included fonts packages in our custom Dockerfile.

I could not find a buildpack to include in order to have fonts support.

How can this be achieved?

user_14447357 · Answer

After more research, it seems that the only solution is to implement our own OCI run image:

FROM paketobuildpacks/run:base-cnb

USER root

RUN apt-get update \
  && apt-get install -y --no-install-recommends \
    libfreetype6 \
    fontconfig \
  && rm -rf /var/lib/apt/lists/*

USER cnb

Then the gradle/maven plugin has to be configured to use it. See Spring's documentation: https://docs.spring.io/spring-boot/docs/current/gradle-plugin/reference/htmlsingle/#build-image.examples.custom-image-builder

user_19785805 · Answer

You can add file fontconfig.bfc from JDK to your image. It's needed to add fonts to your image. There is short sample you also need to add fonts for your image:

https://github.com/mathter/java.notes

https://github.com/mathter/java.notes/tree/main/jasperreports/src/main/docker https://github.com/mathter/java.notes/tree/main/jasperreports/src/main/resources

Spring boot plugin docker OCI image and JasperReports

2 Answers