[CI] Fix-Up Docker Build (Use Python) (#11139)

docker/README.md

@@ -0,0 +1,17 @@
+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
+```

docker/base-deps/Dockerfile

@@ -1,6 +1,6 @@
 # The base-deps Docker image installs main libraries needed to run Ray
 
-# The GPU option is nvidia/cuda:11.0-cudnn8-runtime-ubuntu18.04
+# The GPU option is nvidia/cuda:10.1-cudnn8-runtime-ubuntu18.04
 ARG BASE_IMAGE="ubuntu:focal"
 FROM ${BASE_IMAGE}
 # If this arg is not "autoscaler" then no autoscaler requirements will be included

docker/ray-deps/Dockerfile

@@ -1,5 +1,5 @@
 ARG GPU=""
-FROM rayproject/base-deps:latest"$GPU"
+FROM rayproject/base-deps:nightly"$GPU"
 # If this arg is not "autoscaler" then no autoscaler requirements will be included
 ARG AUTOSCALER="autoscaler"
 ARG WHEEL_PATH

docker/ray-ml/Dockerfile

@@ -1,5 +1,5 @@
 ARG GPU
-FROM rayproject/ray:latest"$GPU"
+FROM rayproject/ray:nightly"$GPU"
 
 # We have to uninstall wrapt this way for Tensorflow compatibility
 COPY requirements.txt ./

docker/ray/Dockerfile

@@ -1,5 +1,5 @@
 ARG GPU
-FROM rayproject/ray-deps:latest"$GPU"
+FROM rayproject/ray-deps:nightly"$GPU"
 ARG WHEEL_PATH
 # For Click
 ENV LC_ALL=C.UTF-8