Overview of how the ray images are built:
Images without a "-cpu" or "-gpu" tag are built on ubuntu/focal. They are just an alias for -cpu (e.g. ray:latest is the same as ray:latest-cpu).
ubuntu/focal
+-- base-deps:cpu
+-- ray-deps:cpu
+-- ray:cpu
+-- ray-ml:cpu
nvidia/cuda
+-- base-deps:gpu
+-- ray-deps:gpu
+-- ray:gpu
+-- ray-ml:gpu