Fix mybinder

Even after #395 the demos do not work on mybinder.org. After some investigation it turned out that some tweaks are to the binder Dockerfile are required.

This changes fixes a warning that the NB_USER and NB_UID args were not consumed. Those are now consumed - verifying the non-root user name and ID are the same as the ones used in the [base image](https://github.com/projectnessie/nessie-demos/pkgs/container/nessie-binder-demos).

The actual fix is the ENTRYPOINT in the binder Dockerfile, which seems to be required, because binder passes custom arguments to jupyter.

See https://mybinder.org/v2/gh/snazy/nessie-demos/fix-mybinder?labpath=notebooks%2Fnessie-iceberg-demo-nba.ipynb

binder/Dockerfile

@@ -1,4 +1,4 @@
-# Base image to use for demos.
+# Base image to use for demos in (my)binder.
 
 # Tag will be automatically generated through pre-commit hook if any changes
 # happened in the docker/ folder
@@ -12,3 +12,22 @@ COPY notebooks/*.ipynb notebooks/
 
 # Copy all the needed datasets for the demos
 COPY datasets/ datasets/
+
+# install the notebook package
+RUN pip install --no-cache --upgrade pip && \
+    pip install --no-cache notebook jupyterlab traitlets
+
+ARG NB_USER
+ARG NB_UID
+
+# Verify that the requested notebook user name+id match the current ones
+RUN id -nu | grep -q $NB_USER
+RUN id -u | grep -q $NB_UID
+
+# Add a custom entrypoint script (required by binder due to custom args)
+USER root
+COPY binder/entrypoint-demos.sh /entrypoint-demos.sh
+RUN chmod +x /entrypoint-demos.sh
+WORKDIR ${HOME}
+USER ${USER}
+ENTRYPOINT ["/entrypoint-demos.sh"]

binder/entrypoint-demos.sh

@@ -0,0 +1,31 @@
+#!/usr/bin/env bash
+#
+# Copyright (C) 2020 Dremio
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+set -e
+
+echo ""
+echo "HELLO WORLD"
+echo "HELLO WORLD"
+echo "HELLO WORLD"
+echo "HELLO WORLD"
+echo ""
+echo "$@" >> /dev/stderr
+echo "$@"
+echo ""
+echo ""
+echo ""
+
+exec "$@"