How to specify target architecture when using Spring Boot gradle task bootBuildImage

I'm trying to build an ARM image on an amd64 node.

This documentation about buildpacks states that I can do it using heroku/builder:24 as the builder image and passing the platform as a parameter --platform linux/arm64

I'm using bootBuildImage gradle task to build my image. I learned how to specify a builder image like:

bootBuildImage {
    archiveFile = war.archiveFile
    if (System.getenv('CI')) {
        builder = "heroku/builder:24"
//...

But I couldn't find any way to pass the platform. Isn't this impossible using the gradle task? Should I revert to building my images using Dockerfiles or using buildpack commands directly?

The future release of Spring Boot, 3.4.0, will provide you with the option to choose the target platform

https://docs.spring.io/spring-boot/3.4-SNAPSHOT/gradle-plugin/packaging-oci-image.html#build-image.customization

bootBuildImage {
    imagePlatform = "linux/arm64"
    [etc]

Like @Daniel Mikusa suggested in the comments, you will need a host that can provide an ARM 64 capability; such as Mac Silicons or probably Linux hosts with arm64 emulation enabled and configured in the Docker Daemon