kotovalexarian-likes-gitlab/gitlab-org--gitlab-foss

Brett Walker b0be58a1b3 Resolve "CE documentation is not CommonMark compliant"

2018-09-06 16:52:18 +00:00

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Markdown

GitLab Flavored Markdown (GFM)

Note: Not all of the GitLab-specific extensions to Markdown that are described in this document currently work on our documentation website.

For the best result, we encourage you to check this document out as rendered by GitLab: markdown.md

GitLab uses (as of 11.1) the CommonMark Ruby Library for Markdown processing of all new issues, merge requests, comments, and other Markdown content in the GitLab system. As of 11.3, wiki pages and Markdown files (.md) in the repositories are also processed with CommonMark. Older content in issues/comments are still processed using the Redcarpet Ruby library.

Where there are significant differences, we will try to call them out in this document.

GitLab uses "GitLab Flavored Markdown" (GFM). It extends the CommonMark specification (which is based on standard Markdown) in a few significant ways to add some useful functionality. It was inspired by GitHub Flavored Markdown.

You can use GFM in the following areas:

comments
issues
merge requests
milestones
snippets (the snippet must be named with a .md extension)
wiki pages
markdown documents inside the repository

You can also use other rich text files in GitLab. You might have to install a dependency to do so. Please see the github-markup gem readme for more information.

Transitioning to CommonMark

You may have Markdown documents in your repository that were written using some of the nuances of RedCarpet's version of Markdown. Since CommonMark uses a slightly stricter syntax, these documents may now display a little strangely since we've transitioned to CommonMark. Numbered lists with nested lists in particular can be displayed incorrectly.

It is usually quite easy to fix. In the case of a nested list such as this:

1. Chocolate
  - dark
  - milk

simply add a space to each nested item:

1. Chocolate
   - dark
   - milk

In the documentation below, we try to highlight some of the differences.

If you have a need to view a document using RedCarpet, you can add the token legacy_render=1 to the end of the url, like this:

https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md?legacy_render=1

If you have a large volume of Markdown files, it can be tedious to determine if they will be displayed correctly or not. You can use the diff_redcarpet_cmark tool (not an officially supported product) to generate a list of files and differences between how RedCarpet and CommonMark render the files. It can give you a great idea if anything needs to be changed - many times nothing will need to changed.

Newlines

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#newlines

GFM honors the markdown specification in how paragraphs and line breaks are handled.

A paragraph is simply one or more consecutive lines of text, separated by one or more blank lines. Line-breaks, or soft returns, are rendered if you end a line with two or more spaces:

Roses are red [followed by two or more spaces]  
Violets are blue

Sugar is sweet

Roses are red
Violets are blue

Sugar is sweet

Multiple underscores in words

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#multiple-underscores-in-words

It is not reasonable to italicize just part of a word, especially when you're dealing with code and names that often appear with multiple underscores. Therefore, GFM ignores multiple underscores in words:

perform_complicated_task

do_this_and_do_that_and_another_thing

perform_complicated_task

do_this_and_do_that_and_another_thing

URL auto-linking

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#url-auto-linking

GFM will autolink almost any URL you copy and paste into your text:

* https://www.google.com
* https://google.com/
* ftp://ftp.us.debian.org/debian/
* smb://foo/bar/baz
* irc://irc.freenode.net/gitlab
* http://localhost:3000

https://www.google.com
https://google.com/
ftp://ftp.us.debian.org/debian/
smb://foo/bar/baz
irc://irc.freenode.net/gitlab
http://localhost:3000

Multiline Blockquote

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#multiline-blockquote

On top of standard Markdown blockquotes, which require prepending > to quoted lines, GFM supports multiline blockquotes fenced by >>>:

>>>
If you paste a message from somewhere else

that

spans

multiple lines,

you can quote that without having to manually prepend `>` to every line!
>>>

If you paste a message from somewhere else

that

spans

multiple lines,

you can quote that without having to manually prepend > to every line!

Code and Syntax Highlighting

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#code-and-syntax-highlighting

GitLab uses the Rouge Ruby library for syntax highlighting. For a list of supported languages visit the Rouge website.

Blocks of code are either fenced by lines with three back-ticks ```, or are indented with four spaces. Only the fenced code blocks support syntax highlighting:

Inline `code` has `back-ticks around` it.

Inline code has back-ticks around it.

Example:

```javascript
var s = "JavaScript syntax highlighting";
alert(s);
```

```python
def function():
    #indenting works just fine in the fenced code block
    s = "Python syntax highlighting"
    print s
```

```ruby
require 'redcarpet'
markdown = Redcarpet.new("Hello World!")
puts markdown.to_html
```

```
No language indicated, so no syntax highlighting.
s = "There is no highlighting for this."
But let's throw in a <b>tag</b>.
```

becomes:

var s = "JavaScript syntax highlighting";
alert(s);

def function():
    #indenting works just fine in the fenced code block
    s = "Python syntax highlighting"
    print s

require 'redcarpet'
markdown = Redcarpet.new("Hello World!")
puts markdown.to_html

No language indicated, so no syntax highlighting.
s = "There is no highlighting for this."
But let's throw in a <b>tag</b>.

Inline Diff

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#inline-diff

With inline diffs tags you can display {+ additions +} or [- deletions -].

The wrapping tags can be either curly braces or square brackets: [+ additions +] or {- deletions -}.

Examples:

- {+ additions +}
- [+ additions +]
- {- deletions -}
- [- deletions -]

However the wrapping tags cannot be mixed as such:

- {+ additions +]
- [+ additions +}
- {- deletions -]
- [- deletions -}

Emoji

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#emoji

Sometimes you want to :monkey: around a bit and add some :star2: to your :speech_balloon:. Well we have a gift for you:

:zap: You can use emoji anywhere GFM is supported. :v:

You can use it to point out a :bug: or warn about :speak_no_evil: patches. And if someone improves your really :snail: code, send them some :birthday:. People will :heart: you for that.

If you are new to this, don't be :fearful:. You can easily join the emoji :family:. All you need to do is to look up one of the supported codes.

Consult the [Emoji Cheat Sheet](https://www.emojicopy.com) for a list of all supported emoji codes. :thumbsup:

Most emoji are natively supported on macOS, Windows, iOS, Android and will fallback to image-based emoji where there is lack of support.

On Linux, you can download [Noto Color Emoji](https://www.google.com/get/noto/help/emoji/) to get full native emoji support.

Ubuntu 18.04 (like many modern Linux distros) has this font installed by default.

Sometimes you want to 🐒 around a bit and add some 🌟 to your 💬. Well we have a gift for you:

⚡ You can use emoji anywhere GFM is supported. ✌️

You can use it to point out a 🐛 or warn about 🙊 patches. And if someone improves your really 🐌 code, send them some 🎂. People will ❤️ you for that.

If you are new to this, don't be 😨. You can easily join the emoji 👪. All you need to do is to look up one of the supported codes.

Consult the Emoji Cheat Sheet for a list of all supported emoji codes. 👍

Most emoji are natively supported on macOS, Windows, iOS, Android and will fallback to image-based emoji where there is lack of support.

On Linux, you can download Noto Color Emoji to get full native emoji support.

Ubuntu 18.04 (like many modern Linux distros) has this font installed by default.

Special GitLab References

GFM recognizes special references.

You can easily reference e.g. an issue, a commit, a team member or even the whole team within a project.

GFM will turn that reference into a link so you can navigate between them easily.

GFM will recognize the following:

input	references
`@user_name`	specific user
`@group_name`	specific group
`@all`	entire team
`namespace/project>`	project
`#12345`	issue
`!123`	merge request
`$123`	snippet
`~123`	label by ID
`~bug`	one-word label by name
`~"feature request"`	multi-word label by name
`%123`	project milestone by ID
`%v1.23`	one-word milestone by name
`%"release candidate"`	multi-word milestone by name
`9ba12248`	specific commit
`9ba12248...b19a04f5`	commit range comparison
`[README](doc/README)`	repository file references
`[README](doc/README#L13)`	repository file line references

GFM also recognizes certain cross-project references:

input	references
`namespace/project#123`	issue
`namespace/project!123`	merge request
`namespace/project%123`	project milestone
`namespace/project$123`	snippet
`namespace/project@9ba12248`	specific commit
`namespace/project@9ba12248...b19a04f5`	commit range comparison
`namespace/project~"Some label"`	issues with given label

It also has a shorthand version to reference other projects from the same namespace:

input	references
`project#123`	issue
`project!123`	merge request
`project%123`	project milestone
`project$123`	snippet
`project@9ba12248`	specific commit
`project@9ba12248...b19a04f5`	commit range comparison
`project~"Some label"`	issues with given label

Task Lists

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#task-lists

You can add task lists to issues, merge requests and comments. To create a task list, add a specially-formatted Markdown list, like so:

- [x] Completed task
- [ ] Incomplete task
    - [ ] Sub-task 1
    - [x] Sub-task 2
    - [ ] Sub-task 3

Completed task
Incomplete task
- Sub-task 1
- Sub-task 2
- Sub-task 3

Tasks formatted as ordered lists are supported as well:

1. [x] Completed task
1. [ ] Incomplete task
    1. [ ] Sub-task 1
    1. [x] Sub-task 2

Completed task
Incomplete task
1. Sub-task 1
2. Sub-task 2

Task lists can only be created in descriptions, not in titles. Task item state can be managed by editing the description's Markdown or by toggling the rendered check boxes.

Videos

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#videos

Image tags with a video extension are automatically converted to a video player.

The valid video extensions are .mp4, .m4v, .mov, .webm, and .ogv.

Here's a sample video:

![Sample Video](img/markdown_video.mp4)

Here's a sample video:

Math

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#math

It is possible to have math written with the LaTeX syntax rendered using KaTeX.

Math written inside $``$ will be rendered inline with the text.

Math written inside triple back quotes, with the language declared as math, will be rendered on a separate line.

Example:

This math is inline $`a^2+b^2=c^2`$.

This is on a separate line
```math
a^2+b^2=c^2
```

Becomes:

This math is inline `a^2+b^2=c^2`.

This is on a separate line

a^2+b^2=c^2

Be advised that KaTeX only supports a subset of LaTeX.

Note: This also works for the asciidoctor :stem: latexmath. For details see the asciidoctor user manual.

Colors

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#colors

It is possible to have color written in HEX, RGB or HSL format rendered with a color indicator.

Color written inside backticks will be followed by a color "chip".

Examples:

`#F00`  
`#F00A`  
`#FF0000`  
`#FF0000AA`  
`RGB(0,255,0)`  
`RGB(0%,100%,0%)`  
`RGBA(0,255,0,0.7)`  
`HSL(540,70%,50%)`  
`HSLA(540,70%,50%,0.7)`

Become:

#F00
#F00A
#FF0000
#FF0000AA
RGB(0,255,0)
RGB(0%,100%,0%)
RGBA(0,255,0,0.7)
HSL(540,70%,50%)
HSLA(540,70%,50%,0.7)

Supported formats:

HEX: `#RGB[A]` or `#RRGGBB[AA]`
RGB: `RGB[A](R, G, B[, A])`
HSL: `HSL[A](H, S, L[, A])`

Mermaid

Introduced in GitLab 10.3.

If this is not rendered correctly, see https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/user/markdown.md#mermaid

It is possible to generate diagrams and flowcharts from text using Mermaid.

In order to generate a diagram or flowchart, you should write your text inside the mermaid block.

Example:

```mermaid
graph TD;
  A-->B;
  A-->C;
  B-->D;
  C-->D;
```

Becomes:

graph TD;
  A-->B;
  A-->C;
  B-->D;
  C-->D;

For details see the Mermaid official page.

Standard Markdown

Headers

# H1
## H2
### H3
#### H4
##### H5
###### H6

Alternatively, for H1 and H2, an underline-ish style:

Alt-H1
======

Alt-H2
------

Header IDs and links

All Markdown-rendered headers automatically get IDs, except in comments.

On hover, a link to those IDs becomes visible to make it easier to copy the link to the header to give it to someone else.

The IDs are generated from the content of the header according to the following rules:

All text is converted to lowercase.
All non-word text (e.g., punctuation, HTML) is removed.
All spaces are converted to hyphens.
Two or more hyphens in a row are converted to one.
If a header with the same ID has already been generated, a unique incrementing number is appended, starting at 1.

For example:

# This header has spaces in it
## This header has a :thumbsup: in it
# This header has Unicode in it: 한글
## This header has spaces in it
### This header has spaces in it
## This header has 3.5 in it (and parentheses)

Would generate the following link IDs:

this-header-has-spaces-in-it
this-header-has-a-in-it
this-header-has-unicode-in-it-한글
this-header-has-spaces-in-it
this-header-has-spaces-in-it-1
this-header-has-3-5-in-it-and-parentheses

Note that the Emoji processing happens before the header IDs are generated, so the Emoji is converted to an image which then gets removed from the ID.

Emphasis

Examples:

Emphasis, aka italics, with *asterisks* or _underscores_.

Strong emphasis, aka bold, with **asterisks** or __underscores__.

Combined emphasis with **asterisks and _underscores_**.

Strikethrough uses two tildes. ~~Scratch this.~~

Become:

Emphasis, aka italics, with asterisks or underscores.

Strong emphasis, aka bold, with asterisks or underscores.

Combined emphasis with asterisks and underscores.

Strikethrough uses two tildes. ~~Scratch this.~~

Lists

Examples:

1. First ordered list item
2. Another item
   * Unordered sub-list.
1. Actual numbers don't matter, just that it's a number
   1. Ordered sub-list
4. And another item.

* Unordered list can use asterisks
- Or minuses
+ Or pluses

Become:

First ordered list item
Another item
- Unordered sub-list.
Actual numbers don't matter, just that it's a number
1. Ordered sub-list
And another item.

Unordered list can use asterisks

Or minuses

Or pluses

If a list item contains multiple paragraphs, each subsequent paragraph should be indented to the same level as the start of the list item text (Redcarpet: paragraph should be indented with four spaces.)

Example:

1. First ordered list item

   Second paragraph of first item.

2. Another item

Becomes:

First ordered list item

Paragraph of first item.
Another item

If the paragraph of the first item is not indented with the proper number of spaces, the paragraph will appear outside the list, instead of properly indented under the list item.

Example:

1. First ordered list item

  Paragraph of first item.

2. Another item

Becomes:

First ordered list item

Paragraph of first item.

Another item

Links

There are two ways to create links, inline-style and reference-style.

[I'm an inline-style link](https://www.google.com)

[I'm a reference-style link][Arbitrary case-insensitive reference text]

[I'm a relative reference to a repository file](LICENSE)

[I am an absolute reference within the repository](/doc/user/markdown.md)

[I link to the Milestones page](/../milestones)

[You can use numbers for reference-style link definitions][1]

Or leave it empty and use the [link text itself][]

Some text to show that the reference links can follow later.

[arbitrary case-insensitive reference text]: https://www.mozilla.org
[1]: http://slashdot.org
[link text itself]: https://www.reddit.com

Note: Relative links do not allow referencing project files in a wiki page or wiki page in a project file. The reason for this is that, in GitLab, wiki is always a separate Git repository. For example, [I'm a reference-style link](style) will point the link to wikis/style when the link is inside of a wiki markdown file.

Images

Examples:

Here's our logo (hover to see the title text):

Inline-style:
![alt text](img/markdown_logo.png)

Reference-style:
![alt text1][logo]

[logo]: img/markdown_logo.png

Become:

Here's our logo:

Inline-style:

Reference-style:

Blockquotes

Examples:

> Blockquotes are very handy in email to emulate reply text.
> This line is part of the same quote.

Quote break.

> This is a very long line that will still be quoted properly when it wraps. Oh boy let's keep writing to make sure this is long enough to actually wrap for everyone. Oh, you can *put* **Markdown** into a blockquote.

Become:

Blockquotes are very handy in email to emulate reply text. This line is part of the same quote.

Quote break.

This is a very long line that will still be quoted properly when it wraps. Oh boy let's keep writing to make sure this is long enough to actually wrap for everyone. Oh, you can put Markdown into a blockquote.

Inline HTML

You can also use raw HTML in your Markdown, and it'll mostly work pretty well.

See the documentation for HTML::Pipeline's SanitizationFilter class for the list of allowed HTML tags and attributes. In addition to the default SanitizationFilter whitelist, GitLab allows span, abbr, details and summary elements.

Examples:

<dl>
  <dt>Definition list</dt>
  <dd>Is something people use sometimes.</dd>

  <dt>Markdown in HTML</dt>
  <dd>Does *not* work **very** well. Use HTML <em>tags</em>.</dd>
</dl>

Become:

Definition list: Is something people use sometimes.
Markdown in HTML: Does *not* work **very** well. Use HTML tags.

Details and Summary

Content can be collapsed using HTML's <details> and <summary> tags. This is especially useful for collapsing long logs so they take up less screen space.

Click me to collapse/fold.

These details will remain hidden until expanded.

PASTE LOGS HERE

Note: Markdown inside these tags is supported, as long as you have a blank link after the </summary> tag and before the </details> tag, as shown in the example. Redcarpet does not support Markdown inside these tags. You can work around this by using HTML, for example you can use <pre><code> tags instead of code fences.

<details>
<summary>Click me to collapse/fold.</summary>

These details _will_ remain **hidden** until expanded.

    PASTE LOGS HERE

</details>

Horizontal Rule

Examples:

Three or more...

---

Hyphens

***

Asterisks

___

Underscores

Become:

Three or more...

Hyphens

Asterisks

Underscores

Line Breaks

A good way to learn how line breaks work is to experiment and discover -- hit Enter once (i.e., insert one newline), then hit it twice (i.e., insert two newlines), see what happens. You'll soon learn to get what you want. The "Preview" tab is your friend.

Here are some things to try out:

Examples:

Here's a line for us to start with.

This line is separated from the one above by two newlines, so it will be a *separate paragraph*.

This line is also a separate paragraph, but...
This line is only separated by a single newline, so it *does not break* and just follows the previous line in the *same paragraph*.

This line is also a separate paragraph, and...  
This line is *on its own line*, because the previous line ends with two spaces. (but still in the *same paragraph*)

spaces.

Become:

Here's a line for us to start with.

This line is separated from the one above by two newlines, so it will be a separate paragraph.

This line is also a separate paragraph, but... This line is only separated by a single newline, so it does not break and just follows the previous line in the same paragraph.

This line is also a separate paragraph, and...
This line is on its own line, because the previous line ends with two spaces. (but still in the same paragraph)

spaces.

Tables

Tables aren't part of the core Markdown spec, but they are part of GFM.

Example:

| header 1 | header 2 |
| -------- | -------- |
| cell 1   | cell 2   |
| cell 3   | cell 4   |

Becomes:

header 1	header 2
cell 1	cell 2
cell 3	cell 4

Note: The row of dashes between the table header and body must have at least three dashes in each column.

By including colons in the header row, you can align the text within that column.

Example:

| Left Aligned | Centered | Right Aligned | Left Aligned | Centered | Right Aligned |
| :----------- | :------: | ------------: | :----------- | :------: | ------------: |
| Cell 1       | Cell 2   | Cell 3        | Cell 4       | Cell 5   | Cell 6        |
| Cell 7       | Cell 8   | Cell 9        | Cell 10      | Cell 11  | Cell 12       |

Becomes:

Left Aligned	Centered	Right Aligned	Left Aligned	Centered	Right Aligned
Cell 1	Cell 2	Cell 3	Cell 4	Cell 5	Cell 6
Cell 7	Cell 8	Cell 9	Cell 10	Cell 11	Cell 12

Footnotes

Example:

You can add footnotes to your text as follows.[^2]
[^2]: This is my awesome footnote.

Becomes:

You can add footnotes to your text as follows.¹

Superscripts / Subscripts

CommonMark and GFM currently do not support the superscript syntax ( x^2 ) that Redcarpet does. You can use the standard HTML syntax for superscripts and subscripts.

The formula for water is H<sub>2</sub>O
while the equation for the theory of relativity is E = mc<sup>2</sup>.

The formula for water is H₂O while the equation for the theory of relativity is E = mc².

Wiki-specific Markdown

The following examples show how links inside wikis behave.

Wiki - Direct page link

A link which just includes the slug for a page will point to that page, at the base level of the wiki.

This snippet would link to a documentation page at the root of your wiki:

[Link to Documentation](documentation)

Wiki - Direct file link

Links with a file extension point to that file, relative to the current page.

If this snippet was placed on a page at <your_wiki>/documentation/related, it would link to <your_wiki>/documentation/file.md:

[Link to File](file.md)

Wiki - Hierarchical link

A link can be constructed relative to the current wiki page using ./<page>, ../<page>, etc.

If this snippet was placed on a page at <your_wiki>/documentation/main, it would link to <your_wiki>/documentation/related:
```
[Link to Related Page](./related)
```
If this snippet was placed on a page at <your_wiki>/documentation/related/content, it would link to <your_wiki>/documentation/main:
```
[Link to Related Page](../main)
```
If this snippet was placed on a page at <your_wiki>/documentation/main, it would link to <your_wiki>/documentation/related.md:
```
[Link to Related Page](./related.md)
```
If this snippet was placed on a page at <your_wiki>/documentation/related/content, it would link to <your_wiki>/documentation/main.md:
```
[Link to Related Page](../main.md)
```

Wiki - Root link

A link starting with a / is relative to the wiki root.

This snippet links to <wiki_root>/documentation:
```
[Link to Related Page](/documentation)
```
This snippet links to <wiki_root>/miscellaneous.md:
```
[Link to Related Page](/miscellaneous.md)
```

References

This document leveraged heavily from the Markdown-Cheatsheet.
The original Markdown Syntax Guide at Daring Fireball is an excellent resource for a detailed explanation of standard markdown.
The detailed specification for CommonMark can be found in the CommonMark Spec
The CommonMark Dingus is a handy tool for testing CommonMark syntax.

This is my awesome footnote. ↩︎

29 KiB Raw Blame History

Markdown

GitLab Flavored Markdown (GFM)

Transitioning to CommonMark

Newlines

Multiple underscores in words

URL auto-linking

Multiline Blockquote

Code and Syntax Highlighting

Inline Diff

Emoji

Special GitLab References

Task Lists

Videos

Math

Colors

Supported formats:

Mermaid

Standard Markdown

Headers

Header IDs and links

Emphasis

Lists

Links

Images

Blockquotes

Inline HTML

Details and Summary

Horizontal Rule

Line Breaks

Tables

Footnotes

Superscripts / Subscripts

Wiki-specific Markdown

Wiki - Direct page link

Wiki - Direct file link

Wiki - Hierarchical link

Wiki - Root link

References

29 KiB

Raw Blame History