I ran into similar issues when following the instructions.
For me, it solved the problems by first creating the builder images locally.
From within the buildpack folder, execute:
docker build -t mendix-rootfs:app -f rootfs-app.dockerfile .
docker build -t mendix-rootfs:builder -f rootfs-builder.dockerfile .
You can then build your app via:
docker build --tag fancydockeruser/fancymendixapp:latest .
The above only works if you have your deployment package extracted to the projects folder within the buildpack. If the location is different, you'll have to used the --build-arg BUILD_PATH="./{project folder}" with the command above.
Good luck!
John
Have a look at: https://github.com/docker/compose/issues/8449
Try adding --platform=linux/amd64 into the two “FROM” build stage that you have inside the Dockerfile.
It should look like this:
.
.
# Build stage
FROM --platform=linux/amd64 ${BUILDER_ROOTFS_IMAGE} AS builder
.
.
FROM --platform=linux/amd64 ${ROOTFS_IMAGE}
Let me know if it’s working out for you….
KH