Spring Boot spring-boot:build-image: how to configure direct memory (MaxDirectMemorySize)?

Question

I use the spring-boot:build-image maven target for building a docker image of my Spring Boot application. I have following setup in my pom.xml

<plugin>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-maven-plugin</artifactId>
    <version>${spring.boot.version}</version>
    <configuration>
        <image>
            <builder>paketobuildpacks/builder:full</builder>
            <runImage>gcr.io/paketo-buildpacks/run:full-cnb</runImage>
            <env>
                <BP_JVM_VERSION>17</BP_JVM_VERSION>
                <JAVA_TOOL_OPTIONS>-XX:MaxDirectMemorySize=64M</JAVA_TOOL_OPTIONS>
            </env>
        </image>
    </configuration>
</plugin>

How can I change the MaxDirectMemorySize? The JAVA_TOOL_OPTIONS environment doesn't work. I still get following console log output on startup:

Calculated JVM Memory Configuration: -XX:MaxDirectMemorySize=10M -Xmx1310134K -XX:MaxMetaspaceSize=275017K -XX:ReservedCodeCacheSize=240M -Xss1M (Total Memory: 2G, Thread Count: 250, Loaded Class Count: 46141, Headroom: 0%)
Picked up JAVA_TOOL_OPTIONS: -Djava.security.properties=/layers/paketo-buildpacks_bellsoft-liberica/java-security-properties/java-security.properties -XX:+ExitOnOutOfMemoryError -XX:ActiveProcessorCount=4 -XX:MaxDirectMemorySize=10M -Xmx1310134K -XX:MaxMetaspaceSize=275017K -XX:ReservedCodeCacheSize=240M -Xss1M -XX:+UnlockDiagnosticVMOptions -XX:NativeMemoryTracking=summary -XX:+PrintNMTStatistics -Dorg.springframework.cloud.bindings.boot.enable=true

How can I increase the max direct memory size? Thanks a lot!

Answer 1

I believe you are trying to apply a runtime configuration (JAVA_TOOL_OPTIONS) to build informations.

According to the spring documentation at https://docs.spring.io/spring-boot/docs/3.0.x/maven-plugin/reference/htmlsingle/#build-image.examples.runtime-jvm-configuration, you should change this to.

        <env>
            <BP_JVM_VERSION>17</BP_JVM_VERSION>
            <BPE_APPEND_JAVA_TOOL_OPTIONS>-XX:MaxDirectMemorySize=64M</BPE_APPEND_JAVA_TOOL_OPTIONS>
        </env>

Does that make it work for you?