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 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>
description: <overview>
weight: <order>
---

Copy the above at the start of your new markdown file and update the <title>, <description> and <weight> 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:

{{< image width="75%" ratio="69.52%"
    link="./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"
    >}}

The width, ratio, link and caption values are required. If the title value isn't supplied, it'll default to the same as caption. If the alt value is not supplied, it'll default to title or if that's not defined, to caption.

width represents the percentage of space used by the image relative to the surrounding text. ratio (image height / image width) * 100.

Adding icons & emojis

You can embed some common icons in your content using:

{{< warning_icon >}}
{{< idea_icon >}}

which look like and

In addition, you can embed an emoji in your content using a sequence such as :sailboat: which looks like ⛵. Here's a handy cheat sheet of the supported emojis.

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:

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

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

2. 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)
   

3. Absolute Link. You use absolute links that start with a / to reference content outside of the current hierarchy:

   [see here](/docs/adir/afile/)
   

Embedding preformatted blocks

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

The above produces this kind of output:

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

You must indicate the nature of the content in the preformatted block by appending a name after the initial set of tick marks:

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, along with command and its variants described below.

Showing commands and command output

If you want to show one or more bash command-lines with some output, you use the command indicator:

which produces:

$ echo "Hello"
Hello

You can have as many command-lines as you want, but only one chunk of output is recognized.

which yields:

$ echo "Hello" >file.txt
$ cat file.txt
Hello

You can also use line continuation in your command-lines:

$ echo "Hello" \
    >file.txt
$ echo "There" >>file.txt
$ cat file.txt
Hello
There

If the output is the command is JSON or YAML, you can use command-output-as-json and command-output-as-yaml instead of merely command in order to apply syntax coloring to the command's output.

Showing references to Istio GitHub files

If your code block references a file from Istio's GitHub repo, you can surround the relative path name of the file with a pair of @ symbols. These indicate the path should be rendered as a link to the file from the current branch. For example:

This will be rendered as:

$ istioctl create -f @samples/bookinfo/kube/route-rule-reviews-v3.yaml@

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 statement such as:

{{< file_content url="https://raw.githubusercontent.com/istio/istio/master/samples/bookinfo/kube/mixer-rule-ratings-ratelimit.yaml" lang="yaml" >}}

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 may be used here.

Referencing GitHub files

When referencing files from Istio's GitHub repo, it is best to reference a specific branch in the repo. To reference the specific branch that the documentation site is currently targeting, you use the annotation {{< branch_name >}}. For example:

See this [source file](https://github.com/istio/istio/blob/{{< branch_name >}}/mixer/cmd/mixs/cmd/server.go)/

Renaming or moving pages

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:

aliases:
    - <url>

For example

---
title: Frequently Asked Questions
description: Questions Asked Frequently
weight: 12
aliases:
    - /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
description: Questions Asked Frequently
weight: 12
aliases:
    - /faq
    - /faq2
    - /faq3
---