Writing a New Topic

This page shows how to create a new Istio documentation topic.

Before you begin

You first need to create a fork of the Istio documentation repository as described in Creating a Doc Pull Request.

Choosing a page type

As you prepare to write a new topic, think about which of these page types is the best fit for your content:

Each page type has a template file located in the corresponding directory which shows you the basic structure expected for topics of that type. Please start new documents by copying the template.

Naming a topic

Choose a title for your topic that has the keywords you want search engines to find. Create a filename for your topic that uses the words in your title, separated by hyphens, all in lower case.

Updating the front matter

Every documentation file needs to start with Jekyll front matter. The front matter is a block of YAML that is between the triple-dashed lines at the top of each file. Here’s the chunk of front matter you should start with:

---
title: <title>
overview: <overview>

order: <order>

layout: docs
type: markdown
---

Copy the above at the start of your new markdown file and update the <title>, <overview> and <order> fields for your particular file. The available front matter fields are:

Choosing a directory

Depending on your page type, put your new file in a subdirectory of one of these:

• _blog/
• _docs/concepts/
• _docs/guides/
• _docs/reference/
• _docs/setup/
• _docs/tasks/

You can put your file in an existing subdirectory, or you can create a new subdirectory. For blog posts, put the file into a subdirectory for the current year (2017, 2018, etc)

Adding images

Put image files in an img subdirectory of where you put your markdown file. The preferred image format is SVG.

If you must use a PNG or JPEG file instead, and the file was generated from an original SVG file, please include the SVG file in the repository even if it isn’t used in the web site itself. This is so we can update the imagery over time if needed.

Within markdown, use the following sequence to add the image:

{% include figure.html width='75%' ratio='69.52%'
    img='./img/myfile.svg'
    alt='Alternate text to display when the image is not available'
    title='A tooltip displayed when hovering over the image'
    caption='A caption displayed under the image'
    %}

You need to fill in all the values. The width represents the percentage of space used by the image relative to the surrounding text. The ratio is (image height / image width) * 100.

Linking to other pages

There are three types of links that can be included in documentation. Each uses a different way to indicate the link target:

• Internet Link. You use classic URL syntax, preferably with the HTTPS protocol, to reference files on the Internet:

  [see here](https://mysite/myfile.html)
  

• Relative Link. You use relative links that start with a period to reference any content that is at the same level as the current file, or below within the hierarchy of the site:

  [see here](./adir/anotherfile.html)
  

• Absolute Link. You use absolute links with the special {{home}} notation to reference content outside of the current hierarchy:

  [see here]({{home}}/docs/adir/afile.html)
  

  In order to use {{home}} in a file, you need to make sure that the file contains the following line of boilerplate right after the block of front matter:

  ...
  ---
  {% include home.html %}
  

  Adding this include statement is what defines the home variable that is used in the link target.

Embedding preformatted blocks

You can embed blocks of preformatted content using the normal markdown technique:

```
func HelloWorld() {
  fmt.Println("Hello World")
}
```

The above produces this kind of output:

func HelloWorld() {
  fmt.Println("Hello World")
}

In general, you should indicate the nature of the content in the preformatted block. You do this by appending a name after the initial set of tick marks

```go
func HelloWorld() {
  fmt.Println("Hello World")
}
```

The above indicates the content is Go source code, which will lead to appropriate syntax coloring as shown here:

func HelloWorld() {
  fmt.Println("Hello World")
}

You can use markdown, yaml, json, java, javascript, c, cpp, csharp, go, html, protobuf, perl, docker, and bash.

Displaying file content

You can pull in an external file and display its content as a preformatted block. This is handy to display a config file or a test file. To do so, you use a Jekyll include statement such as:

{% include file-content.html url='https://raw.githubusercontent.com/istio/istio/master/Makefile' %}

which produces the following result:

If the file is from a different origin site, CORS should be enabled on that site. Note that the GitHub raw content site (raw.githubusercontent.com) is CORS enabled so it may be used here.

Note that unlike normal preformatted blocks, dynamically loaded preformatted blocks unfortunately do not get syntax colored.

Adding redirects

If you move pages around and would like to ensure existing links continue to work, you can add redirects to the site very easily.

In the page that is the target of the redirect (where you’d like users to land), you simply add the following to the front-matter:

redirect_from: <url>

For example

---
title: Frequently Asked Questions
overview: Questions Asked Frequently

order: 12

layout: docs
type: markdown
redirect_from: /faq
---

With the above in a page saved as _help/faq.md, the user will be able to access the page by going to istio.io/help/faq as normal, as well as istio.io/faq.

You can also add many redirects like so:

---
title: Frequently Asked Questions
overview: Questions Asked Frequently

order: 12

layout: docs
type: markdown
redirect_from:
    - /faq
    - /faq2
    - /faq3
---