[SPARK-32204][SPARK-32182][DOCS] Add a quickstart page with Binder integration in PySpark documentation

### What changes were proposed in this pull request?

This PR proposes to:
- add a notebook with a Binder integration which allows users to try PySpark in a live notebook. Please [try this here](https://mybinder.org/v2/gh/HyukjinKwon/spark/SPARK-32204?filepath=python%2Fdocs%2Fsource%2Fgetting_started%2Fquickstart.ipynb).
- reuse this notebook as a quickstart guide in PySpark documentation.

Note that Binder turns a Git repo into a collection of interactive notebooks. It works based on Docker image. Once somebody builds, other people can reuse the image against a specific commit.
Therefore, if we run Binder with the images based on released tags in Spark, virtually all users can instantly launch the Jupyter notebooks.

<br/>

I made a simple demo to make it easier to review. Please see:
- [Main page](https://hyukjin-spark.readthedocs.io/en/stable/). Note that the link ("Live Notebook") in the main page wouldn't work since this PR is not merged yet.
- [Quickstart page](https://hyukjin-spark.readthedocs.io/en/stable/getting_started/quickstart.html)

<br/>

When reviewing the notebook file itself, please give my direct feedback which I will appreciate and address.
Another way might be:
- open [here](https://mybinder.org/v2/gh/HyukjinKwon/spark/SPARK-32204?filepath=python%2Fdocs%2Fsource%2Fgetting_started%2Fquickstart.ipynb).
- edit / change / update the notebook. Please feel free to change as whatever you want. I can apply as are or slightly update more when I apply to this PR.
- download it as a `.ipynb` file:
    ![Screen Shot 2020-08-20 at 10 12 19 PM](https://user-images.githubusercontent.com/6477701/90774311-3e38c800-e332-11ea-8476-699a653984db.png)
- upload the `.ipynb` file here in a GitHub comment. Then, I will push a commit with that file with crediting correctly, of course.
- alternatively, push a commit into this PR right away if that's easier for you (if you're a committer).

References:
- https://pandas.pydata.org/pandas-docs/stable/user_guide/10min.html
- https://databricks.com/jp/blog/2020/03/31/10-minutes-from-pandas-to-koalas-on-apache-spark.html - my own blog post .. :-) and https://koalas.readthedocs.io/en/latest/getting_started/10min.html

### Why are the changes needed?

To improve PySpark's usability. The current quickstart for Python users are very friendly.

### Does this PR introduce _any_ user-facing change?

Yes, it will add a documentation page, and expose a live notebook to PySpark users.

### How was this patch tested?

Manually tested, and GitHub Actions builds will test.

Closes #29491 from HyukjinKwon/SPARK-32204.

Lead-authored-by: HyukjinKwon <[email protected]>
Co-authored-by: Fokko Driesprong <[email protected]>
Signed-off-by: HyukjinKwon <[email protected]>

Author: HyukjinKwon

.github/workflows/build_and_test.yml

@@ -226,7 +226,7 @@ jobs:
       run: |
         # TODO(SPARK-32407): Sphinx 3.1+ does not correctly index nested classes.
         #   See also https://github.com/sphinx-doc/sphinx/issues/7551.
-        pip3 install flake8 'sphinx<3.1.0' numpy pydata_sphinx_theme
+        pip3 install flake8 'sphinx<3.1.0' numpy pydata_sphinx_theme ipython nbsphinx
     - name: Install R 4.0
       run: |
         sudo sh -c "echo 'deb https://cloud.r-project.org/bin/linux/ubuntu bionic-cran40/' >> /etc/apt/sources.list"
@@ -245,10 +245,11 @@ jobs:
         ruby-version: 2.7
     - name: Install dependencies for documentation generation
       run: |
+        # pandoc is required to generate PySpark APIs as well in nbsphinx.
         sudo apt-get install -y libcurl4-openssl-dev pandoc
         # TODO(SPARK-32407): Sphinx 3.1+ does not correctly index nested classes.
         #   See also https://github.com/sphinx-doc/sphinx/issues/7551.
-        pip install 'sphinx<3.1.0' mkdocs numpy pydata_sphinx_theme
+        pip install 'sphinx<3.1.0' mkdocs numpy pydata_sphinx_theme ipython nbsphinx
         gem install jekyll jekyll-redirect-from rouge
         sudo Rscript -e "install.packages(c('devtools', 'testthat', 'knitr', 'rmarkdown', 'roxygen2'), repos='https://cloud.r-project.org/')"
     - name: Scala linter

binder/apt.txt

@@ -0,0 +1 @@
+openjdk-8-jre

binder/postBuild

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+#
+# Licensed to the Apache Software Foundation (ASF) under one or more
+# contributor license agreements.  See the NOTICE file distributed with
+# this work for additional information regarding copyright ownership.
+# The ASF licenses this file to You 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.
+#
+
+# This file is used for Binder integration to install PySpark available in
+# Jupyter notebook.
+
+VERSION=$(python -c "exec(open('python/pyspark/version.py').read()); print(__version__)")
+pip install "pyspark[sql,ml,mllib]<=$VERSION"

dev/create-release/spark-rm/Dockerfile

@@ -36,7 +36,7 @@ ARG APT_INSTALL="apt-get install --no-install-recommends -y"
 # TODO(SPARK-32407): Sphinx 3.1+ does not correctly index nested classes.
 #   See also https://github.com/sphinx-doc/sphinx/issues/7551.
 #   We should use the latest Sphinx version once this is fixed.
-ARG PIP_PKGS="sphinx==3.0.4 mkdocs==1.0.4 numpy==1.18.1 pydata_sphinx_theme==0.3.1"
+ARG PIP_PKGS="sphinx==3.0.4 mkdocs==1.0.4 numpy==1.18.1 pydata_sphinx_theme==0.3.1 ipython==7.16.1 nbsphinx==0.7.1"
 ARG GEM_PKGS="jekyll:4.0.0 jekyll-redirect-from:0.16.0 rouge:3.15.0"
 
 # Install extra needed repos and refresh.
@@ -75,6 +75,7 @@ RUN apt-get clean && apt-get update && $APT_INSTALL gnupg ca-certificates && \
   pip3 install $PIP_PKGS && \
   # Install R packages and dependencies used when building.
   # R depends on pandoc*, libssl (which are installed above).
+  # Note that PySpark doc generation also needs pandoc due to nbsphinx
   $APT_INSTALL r-base r-base-dev && \
   $APT_INSTALL texlive-latex-base texlive texlive-fonts-extra texinfo qpdf && \
   Rscript -e "install.packages(c('curl', 'xml2', 'httr', 'devtools', 'testthat', 'knitr', 'rmarkdown', 'roxygen2', 'e1071', 'survival'), repos='https://cloud.r-project.org/')" && \

dev/lint-python

@@ -196,6 +196,22 @@ function sphinx_test {
         return
     fi
 
+    # TODO(SPARK-32666): Install nbsphinx in Jenkins machines
+    PYTHON_HAS_NBSPHINX=$("$PYTHON_EXECUTABLE" -c 'import importlib.util; print(importlib.util.find_spec("nbsphinx") is not None)')
+    if [[ "$PYTHON_HAS_NBSPHINX" == "False" ]]; then
+        echo "$PYTHON_EXECUTABLE does not have nbsphinx installed. Skipping Sphinx build for now."
+        echo
+        return
+    fi
+
+    # TODO(SPARK-32666): Install ipython in Jenkins machines
+    PYTHON_HAS_IPYTHON=$("$PYTHON_EXECUTABLE" -c 'import importlib.util; print(importlib.util.find_spec("ipython") is not None)')
+    if [[ "$PYTHON_HAS_IPYTHON" == "False" ]]; then
+        echo "$PYTHON_EXECUTABLE does not have ipython installed. Skipping Sphinx build for now."
+        echo
+        return
+    fi
+
     echo "starting $SPHINX_BUILD tests..."
     pushd python/docs &> /dev/null
     make clean &> /dev/null

dev/requirements.txt

@@ -4,3 +4,5 @@ PyGithub==1.26.0
 Unidecode==0.04.19
 sphinx
 pydata_sphinx_theme
+ipython
+nbsphinx

docs/README.md

@@ -63,7 +63,7 @@ See also https://github.com/sphinx-doc/sphinx/issues/7551.
 -->
 
 ```sh
-$ sudo pip install 'sphinx<3.1.0' mkdocs numpy pydata_sphinx_theme
+$ sudo pip install 'sphinx<3.1.0' mkdocs numpy pydata_sphinx_theme ipython nbsphinx
 ```
 
 ## Generating the Documentation HTML

python/docs/source/conf.py

@@ -45,8 +45,20 @@
     'sphinx.ext.viewcode',
     'sphinx.ext.mathjax',
     'sphinx.ext.autosummary',
+    'nbsphinx',  # Converts Jupyter Notebook to reStructuredText files for Sphinx.
+    # For ipython directive in reStructuredText files. It is generated by the notebook.
+    'IPython.sphinxext.ipython_console_highlighting'
 ]
 
+# Links used globally in the RST files.
+# These are defined here to allow link substitutions dynamically.
+rst_epilog = """
+.. |binder| replace:: Live Notebook
+.. _binder: https://mybinder.org/v2/gh/apache/spark/{0}?filepath=python%2Fdocs%2Fsource%2Fgetting_started%2Fquickstart.ipynb
+.. |examples| replace:: Examples
+.. _examples: https://github.com/apache/spark/tree/{0}/examples/src/main/python
+""".format(os.environ.get("RELEASE_TAG", "master"))
+
 # Add any paths that contain templates here, relative to this directory.
 templates_path = ['_templates']
 
@@ -84,7 +96,7 @@
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.
-exclude_patterns = ['_build']
+exclude_patterns = ['_build', '.DS_Store', '**.ipynb_checkpoints']
 
 # The reST default role (used for this markup: `text`) to use for all
 # documents.

python/docs/source/getting_started/index.rst

@@ -20,3 +20,7 @@
 Getting Started
 ===============
 
+.. toctree::
+    :maxdepth: 2
+
+    quickstart