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[[documentation_style_guide]]
= Apache Kudu (incubating) Documentation Style Guide

:author: Kudu Team
:imagesdir: ./images
:icons: font
:toc: left
:toclevels: 3
:doctype: book
:backend: html5
:sectlinks:
:experimental:

This document gives you the information you need to get started contributing to Kudu
documentation. For code contribution guidelines, see
link:contributing.html[Contributing to Kudu].

== Asciidoc
Kudu documentation is written in link:https://en.wikipedia.org/wiki/AsciiDoc[Asciidoc]
and compiled into HTML and output using the link:http://asciidoctor.org/[Asciidoctor]
toolchain. This provides several advantages. Among them:

- Asciidoc is a superset of Markdown, so if you already know Markdown you can get
started right away.
- Github includes support for Asciidoc in its Atom editor, as well as real-time
simplified HTML rendering.
- Patch submissions are small and easy to review.

== Code Standards
Within reason, try to adhere to these standards:

- 100 or fewer columns per line
- 2 spaces rather than tabs for indentation
- No more than 4 nested levels in the documentation if possible: `(Document -> Chapter
-> Section -> Subsection)`
- When possible, provide the language that a code listing is in, using the
`[source,<language>]` macro. for example, `[source,sql]`
- In general, do not indent Asciidoc, as indentation is significant. Code listings
are one exception.

== Building Documentation
To build the documentation locally, you need the Asciidoctor Ruby application. To build the
entire Kudu documentation set, change to the `docs/` directory and run:
[source,bash]
----
asciidoctor -d book -D docs *.adoc
----
This builds the HTML output in a new _docs/_ directory within the current directory.
Some content, such as the per-daemon configuration reference files, is not populated
during a local build.

To view the HTML, open _docs/index.html_ in your local browser.

You can also build only a single chapter. such as _release_notes.adoc_, by passing its name instead.

== Asciidoc Style Guide
Asciidoc supports a lot of syntax that we do not need to use. When possible, stick
with the following, adapted from the
link:https://hbase.apache.org/book.html#_hbase_reference_guide_style_guide_and_cheat_sheet[HBase Reference Guide]:

.AsciiDoc Cheat Sheet
[cols="1,1,a",options="header"]
|===
| Element Type | Desired Rendering | How to do it
| A paragraph | a paragraph | Just type some text with a blank line at the top and bottom.
| Add line breaks within a paragraph without adding blank lines | Manual line breaks | This will break + at the plus sign. Or prefix the whole paragraph with a line containing '[%hardbreaks]'
| Give a title to anything | Colored italic bold differently-sized text | .MyTitle (no space between the period and the words) on the line before the thing to be titled
| In-Line Code or commands | monospace | \`text`
| In-line literal content (things to be typed exactly as shown) | bold mono | \*\`typethis`*
| In-line replaceable content (things to substitute with your own values) | bold italic mono | \*\_typesomething_*
| Code blocks with highlighting | monospace, highlighted, preserve space |
........
[source,java]
----
  myAwesomeCode() {
}
----
........
| Code block included from a separate file | included just as though it were part of the main file |
................
[source,ruby]
----
\include::path/to/app.rb[]
----
................
| Include only part of a separate file | Similar to Javadoc | See http://asciidoctor.org/docs/user-manual/#by-tagged-regions
| File names, directory names, new terms | italic | \_hbase-default.xml_
| External naked URLs | A link with the URL as link text |
----
http://www.google.com
----

| External URLs with text | A link with arbitrary link text |
----
link:http://www.google.com[Google]
----

| Create an internal anchor to cross-reference | not rendered |
----
[[anchor_name]]
----
| Cross-reference an existing anchor using its default title| an internal hyperlink using the element title if available, otherwise using the anchor name |
----
<<anchor_name>>
----
| Cross-reference an existing anchor using custom text | an internal hyperlink using arbitrary text |
----
<<anchor_name,Anchor Text>>
----
| A block image | The image with alt text |
----
image::sunset.jpg[Alt Text]
----
(put the image in the src/main/site/resources/images directory)
| An inline image | The image with alt text, as part of the text flow |
----
image:sunset.jpg [Alt Text]
----
(only one colon)
| Link to a remote image | show an image hosted elsewhere |
----
image::http://inkscape.org/doc/examples/tux.svg[Tux,250,350]
----
(or `image:`)
| Add dimensions or a URL to the image | depends | inside the brackets after the alt text, specify width, height and/or link="http://my_link.com"
| A footnote | subscript link which takes you to the footnote |
----
Some text.footnote:[The footnote text.]
----
| A note or warning with no title | The admonition image followed by the admonition |
----
NOTE: My note here
----

----
WARNING: My warning here
----
| A complex note | The note has a title and/or multiple paragraphs and/or code blocks or lists, etc |
........
.The Title
[NOTE]
====
Here is the note text.
Everything until the second set of four equals signs
is part of the note.
----
some source code
----
====
........
| Bullet lists | bullet lists |
----
* list item 1
----
(see http://asciidoctor.org/docs/user-manual/#unordered-lists)
| Numbered lists | numbered list |
----
. list item 2
----
(see http://asciidoctor.org/docs/user-manual/#ordered-lists)
| Checklists | Checked or unchecked boxes |
Checked:
----
- [*]
----
Unchecked:
----
- [ ]
----
| Multiple levels of lists | bulleted or numbered or combo |
----
. Numbered (1), at top level
* Bullet (2), nested under 1
* Bullet (3), nested under 1
. Numbered (4), at top level
* Bullet (5), nested under 4
** Bullet (6), nested under 5
- [x] Checked (7), at top level
----
| Labelled lists / variablelists | a list item title or summary followed by content |
----
Title:: content

Title::
  content
----
|GUI menu cascades | bold text with arrows to show levels | Use an ASCII arrow.
........
*File -> Print*
........
renders like *File -> Print*
| Sidebars, quotes, or other blocks of text | a block of text, formatted differently from the default | Delimited using different delimiters, see http://asciidoctor.org/docs/user-manual/#built-in-blocks-summary. Some of the examples above use delimiters like \...., ----,====.
........
[example]
====
This is an example block.
====

[source]
----
This is a source block.
----

[note]
====
This is a note block.
====

[quote]
____
This is a quote block.
____
........

*If you want to insert literal Asciidoc content that keeps being interpreted, when in doubt, use eight dots as the delimiter at the top and bottom.*
| Nested Sections | chapter, section, sub-section, etc |
----
= Book (or chapter if the chapter can be built alone, see leveloffset below)

== Chapter (or section if the chapter is standalone)

=== Section (or subsection, etc)

==== Subsection
----

and so on up to 6 levels (think carefully about going deeper than 4 levels, maybe you can just titled paragraphs or lists instead). Note that you can include a book inside another book by adding the `:leveloffset:+1` macro directive directly before your include, and resetting it to 0 directly after. See the _book.adoc_ source for examples, as this is how this guide handles chapters. *Don't do it for prefaces, glossaries, appendixes, or other special types of chapters.*

| Include one file from another | Content is included as though it were inline |

----
include::[/path/to/file.adoc]
----

For plenty of examples. see _docs/docs.adoc_.
| A table | a table | See http://asciidoctor.org/docs/user-manual/#tables. Generally rows are separated by newlines and columns by pipes
| Comment out a single line | A  line is skipped during rendering |
`+//+ This line won't show up`
| Comment out a block | A section of the file is skipped during rendering |
----
////
Nothing between the slashes will show up.
////
----
| Highlight text for review | text shows up with yellow background |
----
Test between #hash marks# is highlighted yellow.
----
|===