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Documentation Style Guide

This page gives writing style guidelines for the Kubernetes documentation. These are guidelines, not rules. Use your best judgment, and feel free to propose changes to this document in a pull request.

For additional information on creating new content for the Kubernetes documentation, read the Documentation Content Guide.

Changes to the style guide are made by SIG Docs as a group. To propose a change or addition, add it to the agenda for an upcoming SIG Docs meeting, and attend the meeting to participate in the discussion.

Note: Kubernetes documentation uses Blackfriday Markdown Renderer along with a few Hugo Shortcodes to support glossary entries, tabs, and representing feature state.

Language

Kubernetes documentation has been translated into multiple languages (see Localization READMEs).

The way of localizing the docs for a different language is described in Localizing Kubernetes Documentation.

The English-language documentation uses U.S. English spelling and grammar.

Documentation formatting standards

Use camel case for API objects

When you refer to an API object, use the same uppercase and lowercase letters that are used in the actual object name. Typically, the names of API objects use camel case.

Don't split the API object name into separate words. For example, use PodTemplateList, not Pod Template List.

Refer to API objects without saying "object," unless omitting "object" leads to an awkward construction.

Do and Don't - API objects
Do Don't
The Pod has two containers. The pod has two containers.
The Deployment is responsible for ... The Deployment object is responsible for ...
A PodList is a list of Pods. A Pod List is a list of pods.
The two ContainerPorts ... The two ContainerPort objects ...
The two ContainerStateTerminated objects ... The two ContainerStateTerminateds ...

Use angle brackets for placeholders

Use angle brackets for placeholders. Tell the reader what a placeholder represents.

  1. Display information about a Pod:

     kubectl describe pod <pod-name> -n <namespace>

    If the namespace of the pod is default, you can omit the '-n' parameter.

Use bold for user interface elements

Do and Don't - Bold interface elements
Do Don't
Click Fork. Click "Fork".
Select Other. Select "Other".

Use italics to define or introduce new terms

Do and Don't - Use italics for new terms
Do Don't
A cluster is a set of nodes ... A "cluster" is a set of nodes ...
These components form the control plane. These components form the control plane.

Use code style for filenames, directories, and paths

Do and Don't - Use code style for filenames, directories, and paths
Do Don't
Open the envars.yaml file. Open the envars.yaml file.
Go to the /docs/tutorials directory. Go to the /docs/tutorials directory.
Open the /_data/concepts.yaml file. Open the /_data/concepts.yaml file.

Use the international standard for punctuation inside quotes

Do and Don't - Use the international standard for punctuation inside quotes
Do Don't
events are recorded with an associated "stage". events are recorded with an associated "stage."
The copy is called a "fork". The copy is called a "fork."

Inline code formatting

Use code style for inline code and commands

For inline code in an HTML document, use the <code> tag. In a Markdown document, use the backtick (`).

Do and Don't - Use code style for inline code and commands
Do Don't
The kubectl runcommand creates a Deployment. The "kubectl run" command creates a Deployment.
For declarative management, use kubectl apply. For declarative management, use "kubectl apply".
Enclose code samples with triple backticks. (```) Enclose code samples with any other syntax.
Use single backticks to enclose inline code. For example, var example = true. Use two asterisks (**) or an underscore (_) to enclose inline code. For example, var example = true.
Use triple backticks before and after a multi-line block of code for fenced code blocks. Use multi-line blocks of code to create diagrams, flowcharts, or other illustrations.
Use meaningful variable names that have a context. Use variable names such as 'foo','bar', and 'baz' that are not meaningful and lack context.
Remove trailing spaces in the code. Add trailing spaces in the code, where these are important, because the screen reader will read out the spaces as well.
Note: The website supports syntax highlighting for code samples, but specifying a language is optional. Syntax highlighting in the code block should conform to the contrast guidelines.

Use code style for object field names and namespaces

Do and Don't - Use code style for object field names
Do Don't
Set the value of the replicas field in the configuration file. Set the value of the "replicas" field in the configuration file.
The value of the exec field is an ExecAction object. The value of the "exec" field is an ExecAction object.
Run the process as a Daemonset in the kube-system namespace. Run the process as a Daemonset in the kube-system namespace.

Use code style for Kubernetes command tool and component names

Do and Don't - Use code style for Kubernetes command tool and component names
Do Don't
The kubelet preserves node stability. The kubelet preserves node stability.
The kubectl handles locating and authenticating to the API server. The kubectl handles locating and authenticating to the apiserver.
Run the process with the certificate, kube-apiserver --client-ca-file=FILENAME. Run the process with the certificate, kube-apiserver --client-ca-file=FILENAME.

Starting a sentence with a component tool or component name

Do and Don't - Starting a sentence with a component tool or component name
Do Don't
The kubeadm tool bootstraps and provisions machines in a cluster. kubeadm tool bootstraps and provisions machines in a cluster.
The kube-scheduler is the default scheduler for Kubernetes. kube-scheduler is the default scheduler for Kubernetes.

Use a general descriptor over a component name

Do and Don't - Use a general descriptor over a component name
Do Don't
The Kubernetes API server offers an OpenAPI spec. The apiserver offers an OpenAPI spec.
Aggregated APIs are subordinate API servers. Aggregated APIs are subordinate APIServers.

Use normal style for string and integer field values

For field values of type string or integer, use normal style without quotation marks.

Do and Don't - Use normal style for string and integer field values
Do Don't
Set the value of imagePullPolicy to Always. Set the value of imagePullPolicy to "Always".
Set the value of image to nginx:1.16. Set the value of image to nginx:1.16.
Set the value of the replicas field to 2. Set the value of the replicas field to 2.

Code snippet formatting

Don't include the command prompt

Do and Don't - Don't include the command prompt
Do Don't
kubectl get pods $ kubectl get pods

Separate commands from output

Verify that the Pod is running on your chosen node:

kubectl get pods --output=wide

The output is similar to this:

NAME     READY     STATUS    RESTARTS   AGE    IP           NODE
nginx    1/1       Running   0          13s    10.200.0.4   worker0

Versioning Kubernetes examples

Code examples and configuration examples that include version information should be consistent with the accompanying text.

If the information is version specific, the Kubernetes version needs to be defined in the prerequisites section of the Task template or the Tutorial template. Once the page is saved, the prerequisites section is shown as Before you begin.

To specify the Kubernetes version for a task or tutorial page, include min-kubernetes-server-version in the front matter of the page.

If the example YAML is in a standalone file, find and review the topics that include it as a reference. Verify that any topics using the standalone YAML have the appropriate version information defined. If a stand-alone YAML file is not referenced from any topics, consider deleting it instead of updating it.

For example, if you are writing a tutorial that is relevant to Kubernetes version 1.8, the front-matter of your markdown file should look something like:

---
title: <your tutorial title here>
min-kubernetes-server-version: v1.8
---

In code and configuration examples, do not include comments about alternative versions. Be careful to not include incorrect statements in your examples as comments, such as:

apiVersion: v1 # earlier versions use...
kind: Pod
...

Kubernetes.io word list

A list of Kubernetes-specific terms and words to be used consistently across the site.

Kubernetes.io word list
Term Usage
Kubernetes Kubernetes should always be capitalized.
Docker Docker should always be capitalized.
SIG Docs SIG Docs rather than SIG-DOCS or other variations.
On-premises On-premises or On-prem rather than On-premise or other variations.

Shortcodes

Hugo Shortcodes help create different rhetorical appeal levels. Our documentation supports three different shortcodes in this category: Note {{< note >}}, Caution {{< caution >}}, and Warning {{< warning >}}.

  1. Surround the text with an opening and closing shortcode.

  2. Use the following syntax to apply a style:

    {{< note >}}
No need to include a prefix; the shortcode automatically provides one. (Note:, Caution:, etc.)
{{< /note >}}

The output is:

Note: The prefix you choose is the same text for the tag.

Note

Use {{< note >}} to highlight a tip or a piece of information that may be helpful to know.

For example:

{{< note >}}
You can _still_ use Markdown inside these callouts.
{{< /note >}}

The output is:

Note: You can still use Markdown inside these callouts.

You can use a {{< note >}} in a list:

1. Use the note shortcode in a list

1. A second item with an embedded note

   {{< note >}}
   Warning, Caution, and Note shortcodes, embedded in lists, need to be indented four spaces. See [Common Shortcode Issues](#common-shortcode-issues).
   {{< /note >}}

1. A third item in a list

1. A fourth item in a list

The output is:

  1. Use the note shortcode in a list

  2. A second item with an embedded note

    Note: Warning, Caution, and Note shortcodes, embedded in lists, need to be indented four spaces. See Common Shortcode Issues.

  3. A third item in a list

  4. A fourth item in a list

Caution

Use {{< caution >}} to call attention to an important piece of information to avoid pitfalls.

For example:

{{< caution >}}
The callout style only applies to the line directly above the tag.
{{< /caution >}}

The output is:

Caution: The callout style only applies to the line directly above the tag.

Warning

Use {{< warning >}} to indicate danger or a piece of information that is crucial to follow.

For example:

{{< warning >}}
Beware.
{{< /warning >}}

The output is:

Warning: Beware.

Katacoda Embedded Live Environment

This button lets users run Minikube in their browser using the Katacoda Terminal. It lowers the barrier of entry by allowing users to use Minikube with one click instead of going through the complete Minikube and Kubectl installation process locally.

The Embedded Live Environment is configured to run minikube start and lets users complete tutorials in the same window as the documentation.

Caution: The session is limited to 15 minutes.

For example:

{{< kat-button >}}

The output is:

Common Shortcode Issues

Ordered Lists

Shortcodes will interrupt numbered lists unless you indent four spaces before the notice and the tag.

For example:

1. Preheat oven to 350˚F

1. Prepare the batter, and pour into springform pan.
   `{{< note >}}Grease the pan for best results.{{< /note >}}`

1. Bake for 20-25 minutes or until set.

The output is:

  1. Preheat oven to 350˚F

  2. Prepare the batter, and pour into springform pan.

    Note: Grease the pan for best results.

  3. Bake for 20-25 minutes or until set.

Include Statements

Shortcodes inside include statements will break the build. You must insert them in the parent document, before and after you call the include. For example:

{{< note >}}
{{< include "task-tutorial-prereqs.md" >}}
{{< /note >}}

Markdown elements

Line breaks

Use a single newline to separate block-level content like headings, lists, images, code blocks, and others. The exception is second-level headings, where it should be two newlines. Second-level headings follow the first-level (or the title) without any preceding paragraphs or texts. A two line spacing helps visualize the overall structure of content in a code editor better.

Headings

People accessing this documentation may use a screen reader or other assistive technology (AT). Screen readers are linear output devices, they output items on a page one at a time. If there is a lot of content on a page, you can use headings to give the page an internal structure. A good page structure helps all readers to easily navigate the page or filter topics of interest.

Do and Don't - Headings
Do Don't
Update the title in the front matter of the page or blog post. Use first level heading, as Hugo automatically converts the title in the front matter of the page into a first-level heading.
Use ordered headings to provide a meaningful high-level outline of your content. Use headings level 4 through 6, unless it is absolutely necessary. If your content is that detailed, it may need to be broken into separate articles.
Use pound or hash signs (#) for non-blog post content. Use underlines (--- or ===) to designate first-level headings.
Use sentence case for headings. For example, Extend kubectl with plugins Use title case for headings. For example, Extend Kubectl With Plugins

Paragraphs

Do and Don't - Paragraphs
Do Don't
Try to keep paragraphs under 6 sentences. Indent the first paragraph with space characters. For example, ⋅⋅⋅Three spaces before a paragraph will indent it.
Use three hyphens (---) to create a horizontal rule. Use horizontal rules for breaks in paragraph content. For example, a change of scene in a story, or a shift of topic within a section. Use horizontal rules for decoration.
Do and Don't - Links
Do Don't
Write hyperlinks that give you context for the content they link to. For example: Certain ports are open on your machines. See Check required ports for more details. Use ambiguous terms such as “click here”. For example: Certain ports are open on your machines. See here for more details.
Write Markdown-style links: [link text](URL). For example: [Hugo shortcodes](/docs/contribute/style/hugo-shortcodes/#table-captions) and the output is Hugo shortcodes. Write HTML-style links: <a href="/media/examples/link-element-example.css" target="_blank">Visit our tutorial!</a>, or create links that open in new tabs or windows. For example: [example website](https://example.com){target="_blank"}

Lists

Group items in a list that are related to each other and need to appear in a specific order or to indicate a correlation between multiple items. When a screen reader comes across a list—whether it is an ordered or unordered list—it will be announced to the user that there is a group of list items. The user can then use the arrow keys to move up and down between the various items in the list. Website navigation links can also be marked up as list items; after all they are nothing but a group of related links.

  • End each item in a list with a period if one or more items in the list are complete sentences. For the sake of consistency, normally either all items or none should be complete sentences.

    Note: Ordered lists that are part of an incomplete introductory sentence can be in lowercase and punctuated as if each item was a part of the introductory sentence.

  • Use the number one (1.) for ordered lists.

  • Use (+), (*), or (-) for unordered lists.

  • Leave a blank line after each list.

  • Indent nested lists with four spaces (for example, ⋅⋅⋅⋅).

  • List items may consist of multiple paragraphs. Each subsequent paragraph in a list item must be indented by either four spaces or one tab.

Tables

The semantic purpose of a data table is to present tabular data. Sighted users can quickly scan the table but a screen reader goes through line by line. A table caption is used to create a descriptive title for a data table. Assistive technologies (AT) use the HTML table caption element to identify the table contents to the user within the page structure.

Content best practices

This section contains suggested best practices for clear, concise, and consistent content.

Use present tense

Do and Don't - Use present tense
Do Don't
This command starts a proxy. This command will start a proxy.

Exception: Use future or past tense if it is required to convey the correct meaning.

Use active voice

Do and Don't - Use active voice
Do Don't
You can explore the API using a browser. The API can be explored using a browser.
The YAML file specifies the replica count. The replica count is specified in the YAML file.

Exception: Use passive voice if active voice leads to an awkward construction.

Use simple and direct language

Use simple and direct language. Avoid using unnecessary phrases, such as saying "please."

Do and Don't - Use simple and direct language
Do Don't
To create a ReplicaSet, ... In order to create a ReplicaSet, ...
See the configuration file. Please see the configuration file.
View the Pods. With this next command, we'll view the Pods.

Address the reader as "you"

Do and Don't - Addressing the reader
Do Don't
You can create a Deployment by ... We'll create a Deployment by ...
In the preceding output, you can see... In the preceding output, we can see ...

Avoid Latin phrases

Prefer English terms over Latin abbreviations.

Do and Don't - Avoid Latin phrases
Do Don't
For example, ... e.g., ...
That is, ... i.e., ...

Exception: Use "etc." for et cetera.

Patterns to avoid

Avoid using "we"

Using "we" in a sentence can be confusing, because the reader might not know whether they're part of the "we" you're describing.

Do and Don't - Patterns to avoid
Do Don't
Version 1.4 includes ... In version 1.4, we have added ...
Kubernetes provides a new feature for ... We provide a new feature ...
This page teaches you how to use Pods. In this page, we are going to learn about Pods.

Avoid jargon and idioms

Some readers speak English as a second language. Avoid jargon and idioms to help them understand better.

Do and Don't - Avoid jargon and idioms
Do Don't
Internally, ... Under the hood, ...
Create a new cluster. Turn up a new cluster.

Avoid statements about the future

Avoid making promises or giving hints about the future. If you need to talk about an alpha feature, put the text under a heading that identifies it as alpha information.

Avoid statements that will soon be out of date

Avoid words like "currently" and "new." A feature that is new today might not be considered new in a few months.

Do and Don't - Avoid statements that will soon be out of date
Do Don't
In version 1.4, ... In the current version, ...
The Federation feature provides ... The new Federation feature provides ...

What's next