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spring-bootdockerbuildpackjava-fontpaketo

How to add extra linux dependencies into a spring-boot buildpack image?

I updated my spring-boot application to use buildpacks to create my docker-image instead of a dockerfile. I also use Apache POI in my application and since that update I get an error when generating an xlsx file. After some digging, I think it happens because the fontconfig and/or ttf-dejavu packages are missing. But how do I add these in the dockerimage? With a dockerfile I would just add something like

RUN apt-get update && apt-get install fontconfig ttf-dejavu

But how do I achieve the same with buildpacks?

Solution

  • This answer assumes that by "... spring-boot application to use buildpacks" you mean the use of the spring-boot:build-image maven goal.

    The issue lays with the default builder (gcr.io/paketo-buildpacks/builder:base) used by the maven plugin. Builder is responsible for configuring the OS image, and the "base" builder doesn't include fontconfig package. .

    The easiest way to enable fontconfig package is to use the "full" builder (gcr.io/paketo-buildpacks/builder:full-cf or gcr.io/paketo-buildpacks/builder:latest); you can do so for example in one of the following ways:

    • by specifying the builder configuration parameter in the maven plugin,

      <project>
<build>
   <plugins>
       <plugin>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-maven-plugin</artifactId>
           <version>2.3.3.BUILD-SNAPSHOT</version>
           <configuration>
               <image>
                   <builder>gcr.io/paketo-buildpacks/builder:latest</builder>
               </image>
           </configuration>
       </plugin>
   </plugins>
</build>
</project>

    • or directly on your mvn command line by adding -Dspring-boot.build-image.builder=gcr.io/paketo-buildpacks/builder:latest.

    However, this is not ideal because the full OS image is much larger (approx. 1.45GB for "full" vs. 644MB for "base" - observed in docker image listing), a fair bit of overhead "just" for enabling fontconfig.

    A more involved approach would require creating a custom builder with custom mixins, in order to create a tailored "base" image with the extra packages. But I personally found it easier to just use the dockerfile approach in this scenario. Some articles on creating a custom builder: