Kong Gateway

3.1.x

You are browsing documentation for an outdated version. See the latest documentation here.

Working with Templates

Kong Portal is built on top of the lua-resty-template templating library, which can be viewed here: https://github.com/bungle/lua-resty-template. Basic usage of the library will be described below. Refer to the source documentation for a more in-depth look at what it can accomplish.

Syntax

(excerpt from lua-resty-templates documentation)

You may use the following tags in templates:

{{expression}}, writes result of expression - HTML escaped
{*expression*}, writes result of expression
{% lua code %}, executes Lua code
{(path-to-partial)}, include partial file by path, you may also supply context for the file {(partials/header.html, { message = "Hello, World" } )}
{-block-}...{-block-}, wraps inside of a {-block-} to a value stored in a blocks table with a key block (in this case), see using blocks. Don’t use predefined block names verbatim and raw.
{-verbatim-}...{-verbatim-} and {-raw-}...{-raw-} are predefined blocks whose inside is not processed by the lua-resty-template but the content is outputted as is.
{# comments #} everything between {# and #} is considered to be commented out (i.e., not outputted or executed).

Show custom properties

You may work with custom properties in your OpenAPI spec. To expose custom properties in Dev Portal, change the property showExtensions to true in the spec-renderer.html file. By default, showExtensions is false.

Partials

Partials are snippets of HTML that layouts can reference. Partials have access to all the same data that its layout does, and can even call other partials. Breaking your code into partials can help organize large pages, as well as allow different layouts share common page elements.

content/index.txt

---
layout: index.html
title: Partials
header_logo: assets/images/example.jpeg
header_nav_items:
  about:
    href: /about
  guides:
    href: /guides
hero_title: Partials Info
hero_description: Partials are wicked sick!
---

layouts/index.html

{(partials/header.html)}
<div class="content">
  {(partials/hero.html)}
</div>
{(partials/footer.html)}

partials/header.html

<header class="row">
  <div class="column">
    <img src="{{page.header_logo}}"/>
  </div>
  <div class="column">
    {(partials/header_nav.html)}
  </div>
</header>

partials/header_nav.html

<ul>
  {% for title, href in each(page.header_nav_items) do %}
    <li><a href="{{href}}">{{title}}</a></li>
  {% end %}
</ul>

partials/hero.html

<h1>{{page.hero_title}}</h1>
<p>{{page.hero_description}}</p>

partials/hero.html

<footer>
  <p>footer</p>
</footer>

Output:

<header class="row">
  <div class="column">
    <img src="assets/images/example.jpeg"/>
  </div>
  <div class="column">
    <ul>
      <li><a href="/about">about</a></li>
      <li><a href="/guieds">guides</a></li>
    </ul>
  </div>
</header>
<h1>Partials Info</h1>
<p>Partials are wicked sick!</p>
<footer>
  <p>footer</p>
</footer>

Blocks

Blocks can be used to embed a view or partial into another template. Blocks are particularly useful when you want different templates to share a common wrapper.

In the example below, notice that the content file is referencing index.html, and not wrapper.html.

content/index.txt

---
layout: index.html
title: Blocks
description: Blocks are the future!
---

layouts/index.html

{% layout = "layouts/wrapper.html" %}    <- syntax declaring where to find the block

{-main-}                                 <- delimiter describing what content renders in block
<div class="content">
  <h1>{{page.title}}</h1>
  <p>{{page.description}}<p>
</div>
{-main-}

layouts/wrapper.html

<!DOCTYPE html>
<html>
  <head>
    <title>Testing lua-resty-template blocks</title>
  </head>
  <body>
    <header>
      <p>header</p>
    </header>
    {*main*}                 <- syntax indicating where to place the block
    <footer>
      <p>footer</p>
    </footer>
  </body>
</html>

Output:

<!DOCTYPE html>
<html>
  <head>
    <title>Testing lua-resty-template blocks</title>
  </head>
  <body>
    <header>
      <p>header</p>
    </header>
    <div class="content">
      <h1>Blocks</h1>
      <p>Blocks are the future!<p>
    </div>
    <footer>
      <p>footer</p>
    </footer>
  </body>
</html>

Collections

Collections are a powerful tool enabling you to render sets of content as a group. Content rendered as a collection share a configurable route pattern, as well as a layout. Collections are configured in your portals portal.conf.yaml file.

The example below shows all the necessary configuration/files needed to render a basic blog collection made up of individual posts.

portal.conf.yaml

name: Kong Portal
theme:
  name: base
collections:
  posts:
    output: true
    route: /:stub/:collection/:name
    layout: post.html

Above you can see a collections object was declared, which is made up of individual collection configurations. In this example, you are configuring a collection called posts. The renderer looks for a root directory called _posts within the content folder for individual pages to render. If you created another collection conf called animals, the renderer would look for a directory called _animals for content files to render. Each configuration item is made up of a few parts:

output
- required: false
- type: boolean
- description: This optional attribute determines whether the collections should render or not. When set to false, virtual routes for the collection are not created.
route
- required: true
- type: string
- default: none
- description: The route attribute is required and tells the renderer what pattern to generate collection routes from. A collection route should always include at least one valid dynamic namespace that uniquely identifies each collection member.
  - Any namespace in the route declaration which begins with : is considered dynamic.
  - Only certain dynamic namespaces are recognized by Kong as valid:
    - :title: Replaces namespace with a contents title, declared in headmatter.
    - :name: Replaces namespace with the filename of a piece of content.
    - :collection: Replaces namespace with name of current collection.
    - :stub: Replaces namespace with value of headmatter.stub in each contents headmatter.
layout
- required: true
  - type: string
  - description: The layout attribute determines what HTML layout the collections use to render. The path root is accessed from within the current themes layouts directory.
    content/_posts/post1.md

---
title: Post One
stub: blog
---

This is my first post!

content/_posts/post2.md

---
title: Post Two
stub: blog
---

This is my second post!

themes/base/layouts/post.html

<h1>{{ page.title }}</h1>
<p>{* page.body *}</p>

Output:

From <kong_portal_gui_url>/blog/posts/post1:

<h1>Post One</h1>
<p>This is my first post!</p>

From <kong_portal_gui_url>/blog/posts/post2:

<h1>Post Two</h1>
<p>This is my second post!</p>

Kong Template Helpers - Lua API

Kong Template Helpers are a collection of objects that give access to your portal data at the time of render and provide powerful integrations into Kong.

Global:

l - Locale helper, first version, gets values from the currently active page.
each - Commonly used helper to iterate over lists or tables.
print - Commonly used helper to print lists / tables.
markdown - Commonly used helper to print lists / tables.
json_decode - Decode JSON to Lua table.
json_encode - Encode Lua table to JSON.

Objects:

portal - The portal object refers to the current workspace portal being accessed.
page - The page object refers to the currently active page and its contents.
user - The user object represents the currently logged in developer accessing the Kong Portal.
theme - The theme object represents the currently active theme and its variables.
tbl = Table helper methods. Examples: map, filter, find, sort.
str = String helper methods. Examples: lower, upper, reverse, endswith.
helpers - Helper functions simplify common tasks or provide easy shortcuts to Kong Portal methods.

Terminology / Definitions:

list - Also referred to commonly as an array ([1, 2, 3]) in Lua is a table-like object ({1, 2, 3}). Lua list index starts at 1 not 0. Values can be accessed by array notation (list[1]).
table - Also commonly known as an object or HashMap ({1: 2}) in Lua looks like ({1 = 2}). Values can be accessed by array or dot notation (table.one or table["one"]).

l(key, fallback)

Returns the current translation by key from the currently active page.

Return Type

string

Usage

Using content/en/example.txt:

---
layout: example.html

locale:
  title: Welcome to {{portal.name}}
  slogan: The best developer portal ever created.
---

Using content/es/example.txt:

---
layout: example.html

locale:
  title: Bienvenido a {{portal.name}}
  slogan: El mejor portal para desarrolladores jamás creado.
---

Using layouts/example.html:

<h1>{* l("title", "Welcome to" .. portal.name) *}</h1>
<p>{* l("slogan", "My amazing developer portal!") *}</p>
<p>{* l("powered_by", "Powered by Kong.") *}</p>

Output:

For en/example:

<h1>Welcome to Kong Portal</h1>
<p>The best developer portal ever created.</p>
<p>Powered by Kong.</p>

For es/example:

<h1>Bienvenido a Kong Portal</h1>
<p>El mejor portal para desarrolladores jamás creado.</p>
<p>Powered by Kong.</p>

Notes

l(...) is a helper from the page object. It can be also accessed via page.l. However, page.l does not support template interpolation (for example, `` will not work.)

each(list_or_table)

Returns the appropriate iterator depending on what type of argument is passed.

Return Type

Iterator

Usage

Template (List):

{% for index, value in each(table) do %}
<ul>
  <li>Index: {{index}}</li>
  <li>Value: {{ print(value) }}</li>
</ul>
{% end %}

Template (Table):

{% for key, value in each(table) do %}
<ul>
  <li>Key: {{key}}</li>
  <li>Value: {{ print(value) }}</li>
</ul>
{% end %}

print(any)

Returns the output of an input value as a string.

Return Type

string

Usage

Template (Table):

<pre>{{print(page)}}</pre>

markdown(string)

Returns HTML from the markdown string passed as an argument. If a string argument is not valid markdown, the function will return the string as is. To render properly, the helper should be used with raw {* *} delimiters.

Return Type

string

Usage

Template (string as an argument):

<pre>{* markdown("##This is Markdown") *}</pre>

Template (content val as an argument):

<pre>{* markdown(page.description) *}</pre>

json_encode(object)

JSON encodes Lua table passed as argument

Return Type

string

Usage

Template:

<pre>{{ json_encode({ dog = cat }) }}</pre>

json_decode(string)

Decodes JSON string argument to Lua table

Return Type

table

Usage

Template:

<pre>{{ print(json_encode('{"dog": "cat"}')) }}</pre>

portal

portal gives access to data relating to the current portal, this includes things like portal configuration, content, specs, and layouts.

portal.workspace
portal.url
portal.api_url
portal.auth
portal.specs
portal.specs_by_tag
portal.developer_meta_fields

You can access the current workspace portal config directly on the portal object like so:

portal[config_key] or portal.config_key

For example portal.auth is a portal config value. You can find a list of config values by reading the portal section of kong.conf.

From kong.conf

The portal only exposes config values that start with portal_, and they can be access by removing the portal_ prefix.

Some configuration values are modified or customized, these customizations are documented under the Portal Members section.

portal.workspace

Returns the current portal’s workspace.

Return Type

string

Usage

Template:

{{portal.workspace}}

Output:

default

portal.url

Returns the current portal’s url with workspace.

Return Type

string

Usage

Template:

{{portal.url}}

Output:

http://127.0.0.1:8003/default

portal.api_url

Returns the configuration value for portal_api_url with the current workspace appended.

Return Type

string or nil

Usage

Template:

{{portal.api_url}}

Output when portal_api_url = http://127.0.0.1:8004:

http://127.0.0.1:8004/default

portal.auth

Returns the current portal’s authentication type.

Return Type

string

Usage

Printing a value

Input:

{{portal.auth}}

Output when portal_auth = basic-auth:

basic-auth

Checking if authentication is enabled

Input:

{% if portal.auth then %}
  Authentication is enabled!
{% end %}

Output when portal_auth = basic-auth:

Authentication is enabled!

portal.specs

Returns an array of specification files contained within the current portal.

Return type

array

Usage

Viewing a content value

Template:

<pre>{{ print(portal.specs) }}</pre>

Output:

{
  {
    "path" = "content/example1_spec.json",
    "content" = "..."
  },
  {
    "path" = "content/documentation/example1_spec.json",
    "content" = "..."
  },
  ...
}

Looping through values

Template:

{% for _, spec in each(portal.specs) %}
  <li>{{spec.path}}</li>
{% end %}

Output:

  <li>content/example1_spec.json</li>
  <li>content/documentation/example1_spec.json</li>

Filter by path

Template:

{% for _, spec in each(helpers.filter_by_path(portal.specs, "content/documentation")) %}
  <li>{{spec.path}}</li>
{% end %}

Output:

  <li>content/documentation/example1_spec.json</li>

portal.developer_meta_fields

Returns an array of developer meta fields available/required by Kong to register a developer.

Return Type

array

Usage

Printing a value

Template:

{{ print(portal.developer_meta_fields) }}

Output:

{
  {
    label    = "Full Name",
    name     = "full_name",
    type     = "text",
    required = true,
  },
  ...
}

Looping through values

Template:

{% for i, field in each(portal.developer_meta_fields) do %}
<ul>
  <li>Label: {{field.label}}</li>
  <li>Name: {{field.name}}</li>
  <li>Type: {{field.type}}</li>
  <li>Required: {{field.required}}</li>
</ul>
{% end %}

Output:

<ul>
  <li>Label: Full Name</li>
  <li>Name: full_name</li>
  <li>Type: text</li>
  <li>Required: true</li>
</ul>
...

page

page gives access to data relating to the current page, which includes things like page url, path, breadcrumbs, and more.

page.route
page.url
page.breadcrumbs
page.body

When you create a new content page, you are able to define key-values. Here you are going to learn how to access those values and a few other interesting things.

You can access the key-values you define directly on the page object like so:

page[key_name] or page.key_name

You can also access nested keys like so:

page.key_name.nested_key

Be careful! To avoid output errors, make sure that the key_name exists before accessing nested_key as shown below:

{{page.key_name and page.key_name.nested_key}}

page.route

Returns the current page’s route/path.

Return Type

string

Usage

Template:

{{page.route}}

Output, given url is http://127.0.0.1:8003/default/guides/getting-started:

guides/getting-started

page.url

Returns the current page’s url.

Return Type

string

Usage

Template:

{{page.url}}

Output, given url is http://127.0.0.1:8003/default/guides/getting-started:

http://127.0.0.1:8003/default/guides/getting-started

page.breadcrumbs

Returns the current page’s breadcrumb collection.

Return Type

table[]

Item Properties

item.path - Full path to item, no forward-slash prefix.
item.display_name - Formatted name.
item.is_first - Is this the first item in the list?
item.is_last - Is this the last item in the list?

Usage

Template:

<div id="breadcrumbs">
  <a href="">Home</a>
  {% for i, crumb in each(page.breadcrumbs) do %}
    {% if crumb.is_last then %}
      / {{ crumb.display_name }}
    {% else %}
      / <a href="{{crumb.path}}">{{ crumb.display_name }}</a>
    {% end %}
  {% end %}
</div>

page.body

Returns the body of the current page as a string. If the route’s content file has a .md or .markdown extension, the body will be parsed from markdown to HTML.

Return Type

string

Usage for .txt, .json, .yaml, .yml templates

index.txt:

This is text content.

Template:

<h1>This is a title</h1>
<p>{{ page.body) }}</p>

Output:

> # This is a title
> This is text content.

Usage for .md, .markdown templates

Template (markdown): Use the raw delimiter syntax {* *} to render markdown within a template.

index.txt

# This is a title
This is text content.

Template:

{* page.body *}

Output:

> # This is a title
> This is text content.

user

user gives access to data relating to the currently authenticated user. User object is only applicable when KONG_PORTAL_AUTH is enabled.

user.is_authenticated
user.has_role
user.get

user.is_authenticated

Returns boolean value as to the current user’s authentication status.

Return Type

boolean

Usage

Template:

{{print(user.is_authenticated)}}

Output:

true

user.has_role

Returns true if a user has a role given as an argument.

Return Type

boolean

Usage

Template:

{{print(user.has_role("blue"))}}

Output:

true

user.get

Takes developer attribute as an argument and returns value if present.

Return Type

any

Usage

Template:

{{user.get("email")}}
{{print(user.get("meta"))}}

Output:

example123@konghq.com
{ "full_name" = "example" }

theme

The theme object exposes values set in your theme.conf.yaml file. In addition, any variable overrides contained in portal.conf.yaml will be included as well.

theme.colors
theme.color
theme.fonts
theme.font

theme.colors

Returns a table of color variables and their values as key-value pairs.

Return Type

table

Usage

theme.conf.yaml:

name: Kong
colors:
  primary:
    value: '#FFFFFF'
    description: 'Primary Color'
  secondary:
    value: '#000000'
    description: 'Secondary Color'
  tertiary:
    value: '#1DBAC2'
    description: 'Tertiary Color'

Template:

{% for k,v in each(theme.colors) do %}
  <p>{{k}}: {{v}}</p>
{% end %}

Output:

<p>primary: #FFFFFF</p>
<p>secondary: #000000</p>
<p>tertiary: #1DBAC2</p>

theme.color

Description

Takes color var by string argument, returns value.

Return Type

string

Usage

theme.conf.yaml:

name: Kong
colors:
  primary:
    value: '#FFFFFF'
    description: 'Primary Color'
  secondary:
    value: '#000000'
    description: 'Secondary Color'
  tertiary:
    value: '#1DBAC2'
    description: 'Tertiary Color'

Template:

<p>primary: {{theme.color("primary")}}</p>
<p>secondary: {{theme.color("secondary")}}</p>
<p>tertiary: {{theme.color("tertiary")}}</p>

Output:

<p>primary: #FFFFFF</p>
<p>secondary: #000000</p>
<p>tertiary: #1DBAC2</p>

theme.fonts

Returns table of font vars and their values as key-value pairs.

Return Type

table

Usage

theme.conf.yaml:

name: Kong
fonts:
  base: Roboto
  code: Roboto Mono
  headings: Lato

Template:

{% for k,v in each(theme.fonts) do %}
  <p>{{k}}: {{v}}</p>
{% end %}

Output:

<p>base: Roboto</p>
<p>code: Roboto Mono</p>
<p>headings: Lato</p>

theme.font

Takes font name by string argument, returns value.

Return Type

string

Usage

theme.conf.yaml:

name: Kong
fonts:
  base: Roboto
  code: Roboto Mono
  headings: Lato

Template:

<p>base: {{theme.font("base")}}</p>
<p>code: {{theme.font("code")}}</p>
<p>headings: {{theme.font("headings")}}</p>

Output:

<p>base: #FFFFFF</p>
<p>code: #000000</p>
<p>headings: #1DBAC2</p>

str

Table containing useful string helper methods.

Usage

.upper() example:

<pre>{{ str.upper("dog") }}</pre>

Methods

str.byte

str.char

str.dump

str.find

str.format

str.gfind

str.gmatch

str.gsub

str.len

str.lower

str.match

str.rep

str.reverse

str.sub

str.upper

str.isalpha

str.isdigit

str.isalnum

str.isspace

str.islower

str.isupper

str.startswith

str.endswith

str.join

str.splitlines

str.split

str.expandtabs

str.lfind

str.rfind

str.replace

str.count

str.ljust

str.rjust

str.center

str.lstrip

str.rstrip

str.strip

str.splitv

str.partition

str.rpartition

str.at

str.lines

str.title

str.shorten

str.quote_string

tbl

Table containing useful table helper methods

Usage

.map() example:

{% tbl.map({"dog", "cat"}, function(item) %}
  {% if item ~= "dog" then %}
    {% return true %}
  {% end %}
{% end) %}

Working with Templates

Syntax

Show custom properties

Partials

content/index.txt

layouts/index.html

partials/header.html

partials/header_nav.html

partials/hero.html

partials/hero.html

Blocks

content/index.txt

layouts/index.html

layouts/wrapper.html

Collections

portal.conf.yaml

content/_posts/post1.md

content/_posts/post2.md

themes/base/layouts/post.html

Kong Template Helpers - Lua API

l(key, fallback)

Return Type

Usage

Notes

each(list_or_table)

Return Type

Usage

print(any)

Return Type

Usage

markdown(string)

Return Type

Usage

json_encode(object)

Return Type

Usage

json_decode(string)

Return Type

Usage

portal

From kong.conf

portal.workspace

Return Type

Usage

portal.url

Return Type

Usage

portal.api_url

Return Type

Usage

portal.auth

Return Type

Usage

portal.specs

Return type

Usage

portal.developer_meta_fields

Return Type

Usage

page

page.route

Return Type

Usage

page.url

Return Type

Usage

page.breadcrumbs

Return Type

Item Properties

Usage

page.body

Return Type

Usage for .txt, .json, .yaml, .yml templates

Usage for .md, .markdown templates

user

user.is_authenticated

Return Type

Usage

user.has_role

Return Type