The SDK headers are baked into the docker image along with the build tools. Once you've loaded the image with
docker load < spark_sdk.img you can run this command to copy them out to your local file system
docker run --rm -it -v $PWD:/out spark_sdk /bin/tar -cvf /out/headers.tar /sdk/include This will copy the headers to the current directory in headers.tar. We still recommend doing the actual build inside the docker environment but having a copy of the headers can be useful for setting up your development environment.