## What changes were proposed in this pull request?
This PR proposes both:
- Add information about Javadoc, SQL docs and few more information in `docs/README.md` and a comment in `docs/_plugins/copy_api_dirs.rb` related with Javadoc.
- Adds some commands so that the script always runs the SQL docs build under `./sql` directory (for directly running `./sql/create-docs.sh` in the root directory).
## How was this patch tested?
Manual tests with `jekyll build` and `./sql/create-docs.sh` in the root directory.
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#19019 from HyukjinKwon/minor-doc-build.
## What changes were proposed in this pull request?
This PR proposes to install `mkdocs` by `pip install` if missing in the path. Mainly to fix Jenkins's documentation build failure in `spark-master-docs`. See https://amplab.cs.berkeley.edu/jenkins/job/spark-master-docs/3580/console.
It also adds `mkdocs` as requirements in `docs/README.md`.
## How was this patch tested?
I manually ran `jekyll build` under `docs` directory after manually removing `mkdocs` via `pip uninstall mkdocs`.
Also, tested this in the same way but on CentOS Linux release 7.3.1611 (Core) where I built Spark few times but never built documentation before and `mkdocs` is not installed.
```
...
Moving back into docs dir.
Moving to SQL directory and building docs.
Missing mkdocs in your path, trying to install mkdocs for SQL documentation generation.
Collecting mkdocs
Downloading mkdocs-0.16.3-py2.py3-none-any.whl (1.2MB)
100% |████████████████████████████████| 1.2MB 574kB/s
Requirement already satisfied: PyYAML>=3.10 in /usr/lib64/python2.7/site-packages (from mkdocs)
Collecting livereload>=2.5.1 (from mkdocs)
Downloading livereload-2.5.1-py2-none-any.whl
Collecting tornado>=4.1 (from mkdocs)
Downloading tornado-4.5.1.tar.gz (483kB)
100% |████████████████████████████████| 491kB 1.4MB/s
Collecting Markdown>=2.3.1 (from mkdocs)
Downloading Markdown-2.6.9.tar.gz (271kB)
100% |████████████████████████████████| 276kB 2.4MB/s
Collecting click>=3.3 (from mkdocs)
Downloading click-6.7-py2.py3-none-any.whl (71kB)
100% |████████████████████████████████| 71kB 2.8MB/s
Requirement already satisfied: Jinja2>=2.7.1 in /usr/lib/python2.7/site-packages (from mkdocs)
Requirement already satisfied: six in /usr/lib/python2.7/site-packages (from livereload>=2.5.1->mkdocs)
Requirement already satisfied: backports.ssl_match_hostname in /usr/lib/python2.7/site-packages (from tornado>=4.1->mkdocs)
Collecting singledispatch (from tornado>=4.1->mkdocs)
Downloading singledispatch-3.4.0.3-py2.py3-none-any.whl
Collecting certifi (from tornado>=4.1->mkdocs)
Downloading certifi-2017.7.27.1-py2.py3-none-any.whl (349kB)
100% |████████████████████████████████| 358kB 2.1MB/s
Collecting backports_abc>=0.4 (from tornado>=4.1->mkdocs)
Downloading backports_abc-0.5-py2.py3-none-any.whl
Requirement already satisfied: MarkupSafe>=0.23 in /usr/lib/python2.7/site-packages (from Jinja2>=2.7.1->mkdocs)
Building wheels for collected packages: tornado, Markdown
Running setup.py bdist_wheel for tornado ... done
Stored in directory: /root/.cache/pip/wheels/84/83/cd/6a04602633457269d161344755e6766d24307189b7a67ff4b7
Running setup.py bdist_wheel for Markdown ... done
Stored in directory: /root/.cache/pip/wheels/bf/46/10/c93e17ae86ae3b3a919c7b39dad3b5ccf09aeb066419e5c1e5
Successfully built tornado Markdown
Installing collected packages: singledispatch, certifi, backports-abc, tornado, livereload, Markdown, click, mkdocs
Successfully installed Markdown-2.6.9 backports-abc-0.5 certifi-2017.7.27.1 click-6.7 livereload-2.5.1 mkdocs-0.16.3 singledispatch-3.4.0.3 tornado-4.5.1
Generating markdown files for SQL documentation.
Generating HTML files for SQL documentation.
INFO - Cleaning site directory
INFO - Building documentation to directory: .../spark/sql/site
Moving back into docs dir.
Making directory api/sql
cp -r ../sql/site/. api/sql
Source: .../spark/docs
Destination: .../spark/docs/_site
Generating...
done.
Auto-regeneration: disabled. Use --watch to enable.
```
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#18984 from HyukjinKwon/sql-doc-mkdocs.
## What changes were proposed in this pull request?
This generates a documentation for Spark SQL built-in functions.
One drawback is, this requires a proper build to generate built-in function list.
Once it is built, it only takes few seconds by `sql/create-docs.sh`.
Please see https://spark-test.github.io/sparksqldoc/ that I hosted to show the output documentation.
There are few more works to be done in order to make the documentation pretty, for example, separating `Arguments:` and `Examples:` but I guess this should be done within `ExpressionDescription` and `ExpressionInfo` rather than manually parsing it. I will fix these in a follow up.
This requires `pip install mkdocs` to generate HTMLs from markdown files.
## How was this patch tested?
Manually tested:
```
cd docs
jekyll build
```
,
```
cd docs
jekyll serve
```
and
```
cd sql
create-docs.sh
```
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#18702 from HyukjinKwon/SPARK-21485.
