Academy on Exoscale Academy

Alert

Mon, 01 Jan 0001 00:00:00 +0000

The academy-theme alert shortcode renders a styled alert box. The type parameter controls the color and icon.

{{< alert type="note" title="Note" >}}Alert content with **Markdown** support.{{< /alert >}}

Parameters:

Parameter	Description	Default
`type`	Alert style: `note`, `info`, `danger`, `warning`	(none)
`title`	Optional title above the alert body	(none)

Examples:

Note

A plain alert with a title.

Note

This alert supports a title and Markdown.

Info

This is an informational alert.

Danger

This is a danger alert.

Warning

This is a warning alert.

Alert (Docsy)

Mon, 01 Jan 0001 00:00:00 +0000

The Docsy alert shortcode renders a colored alert box. The academy-theme overrides this shortcode, so invoking alert will use the academy-theme implementation. This page demonstrates the Docsy color parameter syntax.

{{< alert color="info" title="Info alert" >}}Alert content here.{{< /alert >}}

Parameters:

Parameter	Description	Default
`color`	Bootstrap color: `primary`, `secondary`, `success`, `danger`, `warning`, `info`	(none)
`title`	Optional title text	(none)

Example:

Docsy alert

This block uses the Docsy-style color parameter.

Callout

Mon, 01 Jan 0001 00:00:00 +0000

Callouts highlight important information with a colored left border and an icon. Five types are supported: default (green), info (blue), warning (orange), error (red), and important (teal).

{{< hextra/callout type="info" >}}
Your message here. Supports **Markdown**.
{{< /hextra/callout >}}

Parameters:

Parameter	Description	Default
`type`	Callout style: `default`, `info`, `warning`, `error`, `important`	`default`
`emoji`	Optional emoji to replace the icon (e.g., `"🚀"`)	(none)

Examples:

This is a default callout. It uses a light-bulb icon and green styling.

This is an info callout. Use it to surface supplementary context.

This is a warning callout. Draw attention to potential issues.

This is an error callout. Indicate something that went wrong.

This is an important callout. Emphasize critical information.

🚀

You can use an emoji instead of the default icon.

Figure

Mon, 01 Jan 0001 00:00:00 +0000

{{< figure src="/examples/images/exoscale-icon.png" alt="Exoscale icon" caption="Caption text." >}}

Example:

A Hugo figure shortcode rendering a static image.

Cards

Mon, 01 Jan 0001 00:00:00 +0000

Cards display content in a responsive grid. Wrap individual hextra/card shortcodes inside a hextra/cards container.

{{< hextra/cards cols="3" >}}
 {{< hextra/card link="https://example.com" title="Title" subtitle="Description" icon="document-text" >}}
 {{< hextra/card title="No link" subtitle="This card is not clickable." >}}
{{< /hextra/cards >}}

Container parameters (hextra/cards):

Parameter	Description	Default
`cols`	Number of columns at the `lg` breakpoint	`3`

Card parameters (hextra/card):

Parameter	Description	Default
`title`	Card heading	(required)
`subtitle`	Description text below the title	(none)
`link`	URL the card links to	(none)
`icon`	Icon name from `data/hextra/icons.yaml`	(none)
`image`	Image URL or page-bundle path	(none)
`tag`	Badge text shown in the top-right corner	(none)
`tagColor`	Bootstrap color name for the tag badge	`secondary`

Three-column grid:

Highlight

Mon, 01 Jan 0001 00:00:00 +0000

{{< highlight go "linenos=table,hl_lines=3" >}}
package main
import "fmt"
func main() { fmt.Println("hello") }
{{< /highlight >}}

Example:

1
2
3
4
5
6
7


package main

import "fmt"

func main() {
 fmt.Println("hello from the highlight shortcode")
}

Pageinfo (Docsy)

Mon, 01 Jan 0001 00:00:00 +0000

The Docsy pageinfo shortcode renders a colored page-level info box. The academy-theme overrides this shortcode.

{{< pageinfo color="primary" >}}Notice content here.{{< /pageinfo >}}

Parameters:

Parameter	Description	Default
`color`	Bootstrap color name	(none)

Example:

This block uses the Docsy implementation of `pageinfo` with `color="primary"`.

Blocks Cover and Link Down

Mon, 01 Jan 0001 00:00:00 +0000

{{< blocks/cover title="Cover Title" subtitle="Subtitle" color="dark" height="min" >}}
Cover content here.
{{< blocks/link-down color="info" >}}
{{< /blocks/cover >}}

Example:

Docsy Cover Block

Hero Example

This cover block uses page resources named background and logo.

Details (Collapsible)

Mon, 01 Jan 0001 00:00:00 +0000

The academy-theme details shortcode renders a collapsible content block.

{{< details summary="Click to expand" open="true" >}}
Collapsed content here. Supports **Markdown**.
{{< /details >}}

Parameters:

Parameter	Description	Default
`summary`	Clickable summary text	(empty)
`open`	Set to `"true"` to start expanded	collapsed

Expanded by default:

Academy theme details (open)

This is the academy-theme implementation of the details shortcode. It starts expanded because open="true" is set.

Supports Markdown formatting
Lists, code, and emphasis all render correctly

Collapsed by default:

Details

Mon, 01 Jan 0001 00:00:00 +0000

A collapsible content block built on the native HTML <details> element with card styling and a rotating chevron indicator.

{{< hextra/details title="Click to expand" >}}
Hidden content here. Supports **Markdown**.
{{< /hextra/details >}}

Parameters:

Parameter	Description	Default
`title`	Summary text (supports Markdown)	(empty)
`closed`	Set to `"true"` to render collapsed	open

Open by default:

Click to expand this section

Here is the hidden content revealed when the summary is clicked.

Hugo Details

Mon, 01 Jan 0001 00:00:00 +0000

{{% details summary="Click to expand" open=true %}}
Collapsible content here.
{{% /details %}}

Example:

Blocks Lead

Mon, 01 Jan 0001 00:00:00 +0000

{{< blocks/lead color="primary" height="min" >}}
Lead section content here.
{{< /blocks/lead >}}

Example:

This is a live `blocks/lead` example.

Pageinfo

Mon, 01 Jan 0001 00:00:00 +0000

The academy-theme pageinfo shortcode renders a page-level notice box.

{{< pageinfo >}}Notice content with **Markdown** support.{{< /pageinfo >}}

Example:

This block uses the academy-theme implementation of `pageinfo`. It is useful for rendering page-level status notices, such as deprecation warnings or draft indicators.

Param

Mon, 01 Jan 0001 00:00:00 +0000

{{< param "title" >}}

Example:

Current page title from front matter: Param

Steps

Mon, 01 Jan 0001 00:00:00 +0000

Numbered step lists rendered with CSS counters. Place h3–h6 headings inside the shortcode body — each heading becomes a numbered step.

{{< hextra/steps >}}

### First step
Description of the first step.

### Second step
Description of the second step.

{{< /hextra/steps >}}

Example:

Clone the repository 🔗

git clone https://github.com/layer5io/academy-example.git

Install dependencies 🔗

npm install

Start the development server 🔗

hugo server -D

Blocks Section and Feature

Mon, 01 Jan 0001 00:00:00 +0000

{{< blocks/section color="light" type="container" >}}
 {{< blocks/feature icon="fa-layer-group" title="Title" >}}Description.{{< /blocks/feature >}}
{{< /blocks/section >}}

Example:

Reusable

Use shortcodes to compose reusable content patterns.

Declarative

Keep formatting examples inside Markdown instead of hard-coding HTML everywhere.

Documented

This page shows how each shortcode behaves when rendered.

Chapterstyle

Mon, 01 Jan 0001 00:00:00 +0000

The chapterstyle shortcode wraps content in a <div> with custom inline styles, useful for visually distinguishing chapter or section blocks.

{{% chapterstyle style="padding: 1rem; border: 1px solid #d0d7de; border-radius: 0.75rem; background: #f8fafc;" %}}
Your styled content here.
{{% /chapterstyle %}}

Parameters:

Parameter	Description	Default
`style`	CSS style string applied to the wrapper `<div>`	(none)

Example:

Comment

Mon, 01 Jan 0001 00:00:00 +0000

The comment shortcode hides content from the rendered output. It acts as an invisible annotation — useful for leaving notes in Markdown that readers won’t see.

{{< comment >}}This text is hidden from the rendered page.{{< /comment >}}

Example:

Visible text before the comment. Visible text after the comment.

The text between the comment shortcode tags above is not rendered. View the page source to confirm.

QR

Mon, 01 Jan 0001 00:00:00 +0000

{{< qr text="https://example.com" alt="QR code description" />}}

Example:

Tabs

Mon, 01 Jan 0001 00:00:00 +0000

Tabbed interfaces powered by Bootstrap 5 nav-tabs. Each hextra/tab is nested inside a hextra/tabs container. Tabs support cross-page sync via localStorage when tabs share the same names.

{{< hextra/tabs >}}
 {{< hextra/tab name="Tab One" >}}Content for tab one.{{< /hextra/tab >}}
 {{< hextra/tab name="Tab Two" >}}Content for tab two.{{< /hextra/tab >}}
{{< /hextra/tabs >}}

Tab parameters (hextra/tab):

Parameter	Description	Default
`name`	Tab label	`Tab <N>`
`selected`	Set to `"true"` to pre-select this tab	`false`

Code samples across languages:

Card

Mon, 01 Jan 0001 00:00:00 +0000

{{% card header="Card Header" title="Card title" footer="Card footer" %}}
Card body content here.
{{% /card %}}

Example:

This is a rendered Docsy card shortcode.

Conditional Text

Mon, 01 Jan 0001 00:00:00 +0000

The conditional-text shortcode renders content only when the include-if value matches the site’s params.buildCondition. This is useful for showing content specific to certain build environments or feature flags.

{{< conditional-text include-if="examples" >}}
This text only appears when buildCondition is set to "examples".
{{< /conditional-text >}}

Parameters:

Parameter	Description	Default
`include-if`	Condition string to match against `params.buildCondition`	(required)

Example:

This sentence is rendered because `params.buildCondition` is set to `examples`.

If the text above is not visible, the site’s params.buildCondition does not match "examples".

File Tree

Mon, 01 Jan 0001 00:00:00 +0000

An interactive file tree with expandable/collapsible folders. Compose three shortcodes: hextra/filetree/container, hextra/filetree/folder, and hextra/filetree/file.

{{< hextra/filetree/container >}}
 {{< hextra/filetree/folder name="src" >}}
 {{< hextra/filetree/file name="main.go" >}}
 {{< /hextra/filetree/folder >}}
 {{< hextra/filetree/file name="README.md" >}}
{{< /hextra/filetree/container >}}

Folder parameters:

Parameter	Description	Default
`name`	Folder name	(required)
`state`	`"open"` or `"closed"`	`open`

Example:

- - _index.md
  - getting-started.md
- - _index.md
  - first-post.md
- baseof.html
- index.html
hugo.yaml
package.json

Ref

Mon, 01 Jan 0001 00:00:00 +0000

[Link text]({{< ref "/content-formatting-examples" >}})

Example:

Absolute link to this section: Content formatting examples

Badge

Mon, 01 Jan 0001 00:00:00 +0000

Inline badges with color variants. Supports both positional and named parameter forms.

{{< hextra/badge "Simple badge" >}}
{{< hextra/badge content="Styled" color="green" link="https://example.com" icon="document-text" >}}

Parameters:

Parameter	Description	Default
`content`	Badge text (or use positional param)	(required)
`color`	Color: `gray`, `green`, `blue`, `yellow`, `red`, `purple`, `orange`, `indigo`, `amber`	`gray`
`link`	Optional URL to wrap the badge as a link	(none)
`icon`	Optional icon name from `data/hextra/icons.yaml`	(none)

Color variants:

Default Success Info Warning Error Important Amber

Cardpane

Mon, 01 Jan 0001 00:00:00 +0000

{{% cardpane %}}
 {{% card header="Step 1" %}}First card content.{{% /card %}}
 {{% card header="Step 2" %}}Second card content.{{% /card %}}
{{% /cardpane %}}

Example:

Relref

Mon, 01 Jan 0001 00:00:00 +0000

[Link text]({{< relref "/content-formatting-examples" >}})

Example:

Relative link to this section: Content formatting examples

SVG

Mon, 01 Jan 0001 00:00:00 +0000

The svg shortcode renders an inline SVG icon from assets/icons/{name}.svg.

{{< svg name="layer5-academy-icon" >}}

Parameters:

Parameter	Description	Default
`name`	SVG file name (without extension) from `assets/icons/`	(required)

Example:

The icon renders inline:

Icon

Mon, 01 Jan 0001 00:00:00 +0000

Renders an inline SVG icon from data/hextra/icons.yaml. Useful for embedding icons in running text.

{{< hextra/icon "light-bulb" >}}

Available icons:

Here are a few icons inline: light-bulb, information-circle, exclamation, folder, document-text.

Iframe

Mon, 01 Jan 0001 00:00:00 +0000

{{< iframe src="/examples/frame-example.html" style="min-height: 18rem;" >}}

Example:

Your browser can not display embedded frames. You can access the embedded page via the following link: /examples/frame-example.html

Version

Mon, 01 Jan 0001 00:00:00 +0000

The version shortcode renders a styled version label.

{{< version color="Theme version label:" >}} academy-theme sample output{{< /version >}}

Example:

Theme version label: academy-theme sample output

Vimeo

Mon, 01 Jan 0001 00:00:00 +0000

{{< vimeo 19899678 >}}

Example:

YouTube

Mon, 01 Jan 0001 00:00:00 +0000

{{< youtube 0RKpf3rK57I >}}

Example:

CSV Table

Mon, 01 Jan 0001 00:00:00 +0000

The csvtable shortcode reads static/data/csv/keys-backup.csv and renders a permissions table grouped by category. Each role column shows a check or cross indicator.

{{< csvtable >}}

The CSV file must be located at static/data/csv/keys-backup.csv and contain columns for Category, Function, Feature, and various role names.

Example:

Infrastructure Permissions

Permission	Description	Workspace Admin	Team Admin	Organization Admin	Provider Admin	User Role	Support Role	Audit Role
Create cluster	Allows creating SKS clusters	✅	✅	✅	❌	✅	❌	❌
Delete cluster	Allows deleting SKS clusters	✅	❌	✅	❌	❌	❌	❌

Security Permissions

Permission	Description	Workspace Admin	Team Admin	Organization Admin	Provider Admin	User Role	Support Role	Audit Role
Rotate API key	Allows rotating API keys	❌	✅	✅	✅	❌	❌	✅

PDF

Mon, 01 Jan 0001 00:00:00 +0000

Embeds a PDF file in a responsive iframe.

{{< hextra/pdf "sample.pdf" >}}

Parameters:

Parameter	Description	Default
positional	Path to the PDF file (page resource, asset, or absolute path)	(required)

Example:

X (Twitter)

Mon, 01 Jan 0001 00:00:00 +0000

{{< x user="SanDiegoZoo" id="1453110110599868418" >}}

Example:

Owl bet you'll lose this staring contest 🦉 pic.twitter.com/eJh4f2zncC
— San Diego Zoo Wildlife Alliance (@sandiegozoo) October 26, 2021

CSV Table Roles

Mon, 01 Jan 0001 00:00:00 +0000

The csvtable-roles shortcode reads static/data/csv/keys-backup.csv and renders per-role permission tables showing which functions each role has access to.

{{< csvtable-roles >}}

The CSV file must be located at static/data/csv/keys-backup.csv with the same format used by csvtable.

Example:

Team Admin Role

Permission	Description
Create cluster	Allows creating SKS clusters
Rotate API key	Allows rotating API keys

Organization Admin Role

Permission	Description
Create cluster	Allows creating SKS clusters
Delete cluster	Allows deleting SKS clusters
Rotate API key	Allows rotating API keys

Provider Admin Role

Permission	Description
Rotate API key	Allows rotating API keys

User Role Role

Permission	Description
Create cluster	Allows creating SKS clusters

Support Role Role

Permission	Description

Audit Role Role

Permission	Description
Rotate API key	Allows rotating API keys

Include

Mon, 01 Jan 0001 00:00:00 +0000

Includes the rendered content of another page inline. This shortcode must use the percent-delimiter syntax.

{{% hextra/include "include-snippet" %}}

Parameters:

Parameter	Description	Default
positional	Page path relative to the content directory	(required)

Example (included from a separate page):

This paragraph was pulled in from a separate page using the hextra/include shortcode. It demonstrates how you can compose content from multiple sources into a single page.

Included content supports full Markdown formatting.
Lists, code, and emphasis all render correctly.

Instagram

Mon, 01 Jan 0001 00:00:00 +0000

{{< instagram CxOWiQNP2MO >}}

Example:

View this post on Instagram

Lab Intro

Mon, 01 Jan 0001 00:00:00 +0000

The lab-intro shortcode captures its inner content and stores it on the page scratch pad under the key lab_intro. This allows layout templates to retrieve and display lab introduction text in a dedicated section of the page.

{{% lab-intro %}}
Welcome to this hands-on lab. In this exercise, you will learn how to deploy a cloud native application using Kubernetes. By the end of this lab, you will be able to create a cluster, deploy workloads, and expose services.
{{% /lab-intro %}}

Example:

Term

Mon, 01 Jan 0001 00:00:00 +0000

Wraps a glossary term in an <abbr> tooltip. Hover over the highlighted terms below to see their definitions. Definitions are sourced from data/<lang>/termbase.yaml.

{{< hextra/term "API" >}}

Parameters:

Parameter	Description	Default
`entry`	Glossary abbreviation or full term (named or positional)	(required)

To use this shortcode, create a termbase data file at data/en/termbase.yaml:

- abbr: API
 term: Application Programming Interface
 definition: A set of protocols for building software.

Examples:

Hugo is an SSG that can be controlled via its CLI . Configuration is written in YAML and sites are commonly served through a CDN . Most projects use a CI/CD pipeline to deploy changes automatically. The theme exposes a rich API of shortcodes and partials.

Jupyter

Mon, 01 Jan 0001 00:00:00 +0000

Renders a Jupyter Notebook (.ipynb) as code blocks and Markdown cells.

{{% hextra/jupyter "example-notebook.ipynb" %}}

Parameters:

Parameter	Description	Default
positional	Path or URL to the `.ipynb` file	(required)
`allowUnsafeHTML`	Set to `"true"` to render raw HTML from notebook outputs	`false`

Example:

# A simple Python greeting
message = "Hello from the Academy!"
print(message)

# Generate Fibonacci numbers
def fibonacci(n):
 a, b = 0, 1
 result = []
 for _ in range(n):
 a, b = b, a + b
 result.append(a)
 return result

fibonacci(10)

Asciinema

Mon, 01 Jan 0001 00:00:00 +0000

Embeds an asciinema terminal recording player. The player CSS/JS is loaded from CDN automatically when this shortcode is used.

{{< hextra/asciinema file="demo.cast" >}}

Parameters:

Parameter	Description	Default
`file`	Path or URL to the `.cast` file (also accepts positional param)	(required)
`theme`	Player color theme	`asciinema`
`speed`	Playback speed multiplier	`1`
`autoplay`	Auto-play on load	`false`
`loop`	Loop playback	`false`
`poster`	Poster/thumbnail specification	(none)
`markers`	Comma-separated time markers (e.g., `"5:Intro,10:Demo"`)	(none)

Example:

Code

Mon, 01 Jan 0001 00:00:00 +0000

This is a code block.

Inline code like var foo = "bar"; is supported.

Embedded Design

Mon, 01 Jan 0001 00:00:00 +0000

The meshery-design-embed shortcode renders an interactive Meshery design diagram.

{{< meshery-design-embed
 id="embedded-design-c811e9f4-2522-4eb6-b775-7475545356d8"
 src="./embedded-design-deploy-meshery-using-meshery.js"
>}}

The rendered output is shown below:

Open Design

Learn more about embedded designs.

Footnotes

Mon, 01 Jan 0001 00:00:00 +0000

This is a superscript number for your footnote. ¹

This is a footnote. ↩︎

Image

Mon, 01 Jan 0001 00:00:00 +0000

Theme image shortcode

Exoscale icon displayed with the academy-theme image shortcode

Image Styling

Mon, 01 Jan 0001 00:00:00 +0000

By default, Markdown images are written like this:

![Alt text](/path/to/image.png)

These are rendered with:

max-width: 70% of the viewport
max-height: 80vh of the viewport height
centered block layout

This default styling works well for most landscape (horizontal) images. However, if an image is very tall, narrow, or otherwise looks awkward, you can override the default by embedding raw HTML and specifying a custom size:

<img src="./images/example.png" alt="Example description"
style="max-width: 40vw; max-height: 60vh; display: block; margin: 1rem auto;" />

Imgproc

Mon, 01 Jan 0001 00:00:00 +0000

This image was processed from a page resource using the Docsy `imgproc` shortcode.

Lists

Mon, 01 Jan 0001 00:00:00 +0000

Unordered:

Liverpool F.C.
Chelsea F.C.
Manchester United F.C.

Ordered:

Michael Brecker
Seamus Blake
Branford Marsalis

Task list:

Create a Hugo theme
Add task lists to it
Take a vacation

Local Video

Mon, 01 Jan 0001 00:00:00 +0000

The local-video shortcode embeds an HTML5 <video> player for a locally hosted video file.

{{< local-video src="/path/to/video.mp4" muted="true" autoplay="true" loop="true" >}}

Parameters:

Parameter	Description	Default
`src`	Path to the video file	(required)
`muted`	Mute the video	`false`
`autoplay`	Auto-play the video	`false`
`loop`	Loop playback	`false`

Sample video not included

This shortcode requires a locally hosted .mp4 video file. Add your video to static/examples/ and update the src path.

Markdown Basics

Mon, 01 Jan 0001 00:00:00 +0000

Text can be bold, italic, or ~~strikethrough~~. Links have no underline (unless hovered).

Blockquotes are lighter with a left border.

Meshery Design Embed

Mon, 01 Jan 0001 00:00:00 +0000

Open Design

Readfile

Mon, 01 Jan 0001 00:00:00 +0000

The readfile shortcode includes the contents of a file inline. When code="true" is set, the contents are rendered inside a code block.

{{< readfile file="/static/examples/openapi/example.json" code="true" lang="json" >}}

{
 "openapi": "3.0.0",
 "info": {
 "title": "Example Academy API",
 "version": "1.0.0",
 "description": "A sample API specification for demonstrating the Redoc and SwaggerUI shortcodes."
 },
 "paths": {
 "/api/courses": {
 "get": {
 "summary": "List courses",
 "description": "Returns a list of all available courses.",
 "responses": {
 "200": {
 "description": "A list of courses.",
 "content": {
 "application/json": {
 "schema": {
 "type": "array",
 "items": {
 "$ref": "#/components/schemas/Course"
 }
 }
 }
 }
 }
 }
 }
 },
 "/api/courses/{id}": {
 "get": {
 "summary": "Get a course",
 "description": "Returns a single course by ID.",
 "parameters": [
 {
 "name": "id",
 "in": "path",
 "required": true,
 "schema": { "type": "string" }
 }
 ],
 "responses": {
 "200": {
 "description": "A course object.",
 "content": {
 "application/json": {
 "schema": { "$ref": "#/components/schemas/Course" }
 }
 }
 },
 "404": { "description": "Course not found." }
 }
 }
 }
 },
 "components": {
 "schemas": {
 "Course": {
 "type": "object",
 "properties": {
 "id": { "type": "string", "example": "cloud-101" },
 "title": { "type": "string", "example": "Cloud Fundamentals" },
 "description": { "type": "string", "example": "An introduction to cloud computing concepts." },
 "duration": { "type": "string", "example": "2 hours" }
 }
 }
 }
 }
}

Redoc

Mon, 01 Jan 0001 00:00:00 +0000

Responsive Images

Mon, 01 Jan 0001 00:00:00 +0000

Small images should be shown at their actual size.

Large images should always scale down and fit in the content container.

The photo above of the Spruce Picea abies shoot with foliage buds: Bjørn Erik Pedersen, CC-BY-SA.

Solution

Mon, 01 Jan 0001 00:00:00 +0000

On the controlplane node, create the file /etc/kubernetes/audit-policy.yaml with the following content:
```
apiVersion: audit.k8s.io/v1
kind: Policy
rules:
- level: Metadata
```

Edit the API Server Pod specification (in the file /etc/kubernetes/manifests/kube-apiserver.yaml) by adding the following two volume definitions:

- name: audit
 hostPath:
 path: /etc/kubernetes/audit-policy.yaml
 type: File
- name: audit-log
 hostPath:
 path: /var/log/kubernetes/audit/
 type: DirectoryOrCreate

and also add the following entries to the volumeMounts field of the container:

- mountPath: /etc/kubernetes/audit-policy.yaml
 name: audit
 readOnly: true
- mountPath: /var/log/kubernetes/audit/
 name: audit-log
 readOnly: false

Start a simple Pod:

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Check the current certificate expiration dates

Run the following command from the control plane node.

sudo kubeadm certs check-expiration

This command shows all certificates managed by kubeadm and their expiration dates:

admin.conf (client certificate for kubectl)
apiserver (API server serving certificate)
apiserver-etcd-client (API server to etcd client certificate)
apiserver-kubelet-client (API server to kubelet client certificate)
controller-manager.conf (controller manager client certificate)
etcd-healthcheck-client (etcd health check client certificate)
etcd-peer (etcd peer certificate for cluster communication)
etcd-server (etcd server certificate)
front-proxy-client (front proxy client certificate)
scheduler.conf (scheduler client certificate)
super-admin.conf (client certificate bypassing authorization layer)

By default, kubeadm certificates are valid for 1 year. You should renew them before they expire to avoid cluster outages.
Certificate are automatically renewed during each upgrade of the control plane.

Renew the certificates using kubeadm

You can renew all certificates at once.

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Create a Deployment with 6 replicas of Pods based on the nginx:1.20 image

k create deploy www --image=nginx:1.20 --replicas=4

Where are the pods scheduled ?

The pods are splitted between worker1 and worker2 (because master node has a NoScheduled taint that the pods do not tolerate)

k get po -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
www-644dfdf68b-6mk2w 1/1 Running 0 33s 10.38.0.1 worker2 <none> <none>
www-644dfdf68b-crdjl 1/1 Running 0 33s 10.32.0.6 worker1 <none> <none>
www-644dfdf68b-nhm7b 1/1 Running 0 33s 10.32.0.2 worker1 <none> <none>
www-644dfdf68b-tsw84 1/1 Running 0 33s 10.38.0.5 worker2 <none> <none>

Drain the worker1 node. What happened ?

k drain worker1 --ignore-daemonsets

The application pods have been evicted from worker1 and are now all running on worker2

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Install the metrics server (https://github.com/kubernetes-sigs/metrics-server)

k apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

Verify it’s not running correctly

Trying to get the Nodes or Pods metrics should return an error

k top node
Error from server (ServiceUnavailable): the server is currently unable to handle the request (get nodes.metrics.k8s.io)

k top pod
Error from server (ServiceUnavailable): the server is currently unable to handle the request (get pods.metrics.k8s.io)

Checking the logs of the metrics-server pod will provide additional details

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Create a Deployment named web-app with 6 replicas using nginx:1.26 image

kubectl create deployment web-app --image=nginx:1.26 --replicas=6

Create a DaemonSet named monitoring using nginx:alpine image

kubectl create -f - <<EOF
apiVersion: apps/v1
kind: DaemonSet
metadata:
 name: monitoring
spec:
 selector:
 matchLabels:
 app: monitoring
 template:
 metadata:
 labels:
 app: monitoring
 spec:
 containers:
 - name: monitoring
 image: nginx:alpine
 ports:
 - containerPort: 80
EOF

Check how Pods are distributed across all Nodes

kubectl get pods -o wide

You should see Pods are distributed across worker Nodes, and one monitoring Pod per Node.

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Test

If you try to list the Nodes, you’ll get an error similar to the following one:

$ kubectl get no

The connection to the server 192.168.64.17:6443 was refused - did you specify the right host or port?

Identification

As kubectl targets the API Server, first make sure this one is running fine.

On the controlplane Node, check the APIServer’s logs in /var/log/syslog. You should see that the API Server cannot start correctly:

Solution

Mon, 01 Jan 0001 00:00:00 +0000

The worker1 has the NotReady status

$ kubectl get no
NAME STATUS ROLES AGE VERSION
master Ready control-plane,master 2d16h v1.32.7
worker1 NotReady <none> 2d16h v1.32.7
worker2 Ready <none> 2d16h v1.32.7

The description of the node provide additional information

$ kubectl describe node worker1
...
Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Normal RegisteredNode 57m node-controller Node worker1 event: Registered Node worker1 in Controller
 Normal NodeNotReady 25m node-controller Node worker1 status is now: NodeNotReady
 Normal Starting 24m kubelet Starting kubelet.
 Normal NodeReady 24m kubelet Node worker1 status is now: NodeReady
 Normal NodeAllocatableEnforced 24m kubelet Updated Node Allocatable limit across pods
 Normal NodeHasSufficientMemory 24m (x2 over 24m) kubelet Node worker1 status is now: NodeHasSufficientMemory
 Normal NodeHasNoDiskPressure 24m (x2 over 24m) kubelet Node worker1 status is now: NodeHasNoDiskPressure
 Normal NodeHasSufficientPID 24m (x2 over 24m) kubelet Node worker1 status is now: NodeHasSufficientPID
 Normal RegisteredNode 22m node-controller Node worker1 event: Registered Node worker1 in Controller
 Normal RegisteredNode 96s node-controller Node worker1 event: Registered Node worker1 in Controller
 Normal NodeNotReady 26s node-controller Node worker1 status is now: NodeNotReady

The Node in NodeNotReady status may indicate kubelet is having trouble. We have the confirmation checking the kubelet status with systemctl on this specific Node.

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Test

Let’s create a new Pod and expose it with a ClusterIP Service

kubectl run nginx --image=nginx:1.20 --port 80 --expose

Let’s new get an interactive shell in an Alpine based Pod

kubectl run -ti --rm debug --image=alpine -- sh

We cannot reach the nginx Pod from the debug one:

/ # wget http://nginx
wget: bad address 'nginx'

Going one step further we can see the name resolution is not working fine:

/ # nslookup nginx
;; connection timed out; no servers could be reached

Checking the cluster’s internal DNS

kubectl get deploy -n kube-system
NAME READY UP-TO-DATE AVAILABLE AGE
coredns 0/0 0 0 2d17h

Seems like there is no replica running for the dns (should be 2 by default)

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Test

List the resources in app2

$ kubectl get po,svc -n app2
NAME READY STATUS RESTARTS AGE
pod/nginx 1/1 Running 0 8s

NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/nginx NodePort 10.106.164.238 <none> 80:30000/TCP 8s

From a worker node, try to reach the nginx Pod

$ curl localhost:30000
curl: (7) Failed to connect to localhost port 30000: Connection refused

Check the service

kubectl describe svc nginx -n app2
Name: nginx
Namespace: app2
Labels: <none>
Annotations: <none>
Selector: app=nginx
Type: NodePort
IP Family Policy: SingleStack
IP Families: IPv4
IP: 10.106.164.238
IPs: 10.106.164.238
Port: <unset> 80/TCP
TargetPort: 80/TCP
NodePort: <unset> 30000/TCP
Endpoints: <none>
Session Affinity: None
External Traffic Policy: Cluster
Events: <none>

The list of Endpoints is empty, that is surely a problem. The Service’s selector is app: nginx, let’s see the content of the Pod’s labels.

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Test

The single replica is not running

kubectl get deploy,po -n app1
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/nginx 0/1 1 0 79m

NAME READY STATUS RESTARTS AGE
pod/nginx-7b4b5bbf6f-dth6d 0/1 ImagePullBackOff 0 79m

The description of the nginx Pod gives additional information

kubectl describe po pod/nginx-7b4b5bbf6f-dth6d
...
Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Normal BackOff 16s (x351 over 80m) kubelet Back-off pulling image "ngnix:1.26"

Fix it

Edit the Deployment and replace the image name ngnix:1.26 with nginx:1.26, a little typo can have big consequences :)

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Test

Try to create a pod:

kubectl run ghost --image=ghost:4

Verify it is running:

$ kubectl get po
NAME READY STATUS RESTARTS AGE
ghost 0/1 Pending 0 10s

There is definitely something wrong as the pod remains in pending status.

$ kubectl describe po ghost
...
Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Warning FailedScheduling 4s (x2 over 72s) default-scheduler 0/3 nodes are available: 3 node(s) had taint {app: secure}, that the pod didn't tolerate.

It seems the 3 nodes have a taint that prevents the pod from being scheduled. We can see there are 2 taints on the master:

Solution

Mon, 01 Jan 0001 00:00:00 +0000

Observe the behavior of the pod you will notice the pod is automatically restarted after a few tens of seconds:

$ kubectl get po -w
NAME READY STATUS RESTARTS AGE
demo 1/1 Running 0 2s
demo 1/1 Running 1 (1s ago) 76s

Going a little deeper in the details, we understand this is due to the liveness probe failing:

$ kubectl describe po demo
...
Events:
 Type Reason Age From Message
 ---- ------ ---- ---- -------
 Normal Scheduled 2m8s default-scheduler Successfully assigned default/demo to worker1
 Normal Pulled 2m7s kubelet Successfully pulled image "k8s.gcr.io/busybox" in 578.053377ms
 Normal Pulling 53s (x2 over 2m7s) kubelet Pulling image "k8s.gcr.io/busybox"
 Normal Created 52s (x2 over 2m6s) kubelet Created container busybox
 Normal Started 52s (x2 over 2m6s) kubelet Started container busybox
 Normal Pulled 52s kubelet Successfully pulled image "k8s.gcr.io/busybox" in 512.064103ms
 Warning Unhealthy 8s (x6 over 93s) kubelet Liveness probe failed: cat: can't open '/tmp/healthy': No such file or directory
 Normal Killing 8s (x2 over 83s) kubelet Container busybox failed liveness probe, will be restarted

If we check the pod’s specification, we can see the liveness probe checks the existence of a file:

SwaggerUI

Mon, 01 Jan 0001 00:00:00 +0000

Tables

Mon, 01 Jan 0001 00:00:00 +0000

Artist	Album	Year
Michael Jackson	Thriller	1982
Prince	Purple Rain	1984
Beastie Boys	License to Ill	1986

Inline code inside table cells:

Language	Code
JavaScript	`var foo = "bar";`
Ruby	`foo = "bar"`

Tabpane and Tab

Mon, 01 Jan 0001 00:00:00 +0000

This is the first rendered tab.

TabPanel

Mon, 01 Jan 0001 00:00:00 +0000

Tabs help organize related content.

Concise explanation
Another brief point

Tabs help organize related content.

Concise explanation
Another brief point

Here is an example image:

Usestatic

Mon, 01 Jan 0001 00:00:00 +0000

The usestatic shortcode resolves a tenant-scoped static file path, prefixing it with the organization UUID configured in params.defined_org.

{{< usestatic "images/exoscale-icon.png" >}}

Resolved tenant-scoped static path: /academy-theme/images/exoscale-icon.png