Convert FROM specification to ARG (#727)

all-spark-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-FROM jupyter/pyspark-notebook
+ARG BASE_CONTAINER=jupyter/pyspark-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

base-notebook/Dockerfile

@@ -3,7 +3,8 @@
 
 # Ubuntu 18.04 (bionic) from 2018-05-26
 # https://github.com/docker-library/official-images/commit/aac6a45b9eb2bffb8102353c350d341a410fb169
-FROM ubuntu:bionic-20180526@sha256:c8c275751219dadad8fa56b3ac41ca6cb22219ff117ca98fe82b42f24e1ba64e
+ARG BASE_CONTAINER=ubuntu:bionic-20180526@sha256:c8c275751219dadad8fa56b3ac41ca6cb22219ff117ca98fe82b42f24e1ba64e
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

datascience-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-FROM jupyter/scipy-notebook
+ARG BASE_CONTAINER=jupyter/scipy-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

minimal-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-
-FROM jupyter/base-notebook
+ARG BASE_CONTAINER=jupyter/base-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

pyspark-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-FROM jupyter/scipy-notebook
+ARG BASE_CONTAINER=jupyter/scipy-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

r-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-FROM jupyter/minimal-notebook
+ARG BASE_CONTAINER=jupyter/minimal-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

scipy-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-FROM jupyter/minimal-notebook
+ARG BASE_CONTAINER=jupyter/minimal-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 

tensorflow-notebook/Dockerfile

 # Copyright (c) Jupyter Development Team.
 # Distributed under the terms of the Modified BSD License.
-FROM jupyter/scipy-notebook
+ARG BASE_CONTAINER=jupyter/scipy-notebook
+FROM $BASE_CONTAINER
 
 LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"