Light modules

what is a light module

A Magnolia light module is a file and folder-based module. It can define every Magnolia item which can be configured in YAML – such as apps, content types, templates, dialogs, themes, and others. It can also contain a lightweight YAML-based module descriptor and web resources such as css and javascript files.

Light modules can be built with a simple text editor, with no special tools (such as Maven) required. A light module cannot incorporate java classes.

Light module structure

Example of light module structure:

magnolia.resources.dir/
└── foo/
    ├── apps
    ├── blocks
    ├── contentTypes
    ├── decorations
    ├── dialogs
    │ ├── components
    │ └── pages
    ├── i18n
    │ └── foo-messages_en.properties
    ├── includes
    │ └── README.txt
    ├── messageViews
    ├── README.md
    ├── restEndpoints
    ├── templates
    │ ├── components
    │ └── pages
    ├── themes
    ├── virtualUriMappings
    └── webresources

(This example structure was created using version 3.1.0 of Magnolia CLI and setting comprehensive as the value of the -P flag of the create-light-module CLI command.)

Light modules folder: magnolia.resources.dir

Magnolia light modules must reside within the Magnolia resources directory; this directory is also often referred to as the Magnolia light modules folder. The name and the location of this directory are arbitrary, but you must provide the path to the folder via configuration.

What is magnolia.resources.dir

magnolia.resources.dir is a property defining the directory from which resources are loaded in a Magnolia instance. This directory is used for file-based resources such as light modules and for overriding classpath resources. The property is configured in WEB-INF/config/default/magnolia.properties and its default value is $magnolia.home/modules. To see the current value of the property, go to the Config Info tab in the About Magnolia app.

You can use symbolic links (symlinks or soft links) in the resources directory to include light modules located elsewhere on your system.

Set the magnolia.resources.filesystem.observation.excludedDirectories property to exclude directories from being observed for changes. (See Configuration management - magnolia.resources.filesystem.observation.excludedDirectories.)

A change in the light modules folder may also flush the server cache. You can configure this behavior under /modules/cache/config/contentCaching/defaultPageCache/flushPolicy/policies/lightModule/pathToCacheMappings/defaultPageCache with the pattern property, which specifies the pattern for the operation. The default value is ./(templates|webresources|i18n)/..

What items can be defined in a light module?

The following items can be defined within a light module using YAML. Items defined by YAML can be decorated, or can be reused with YAML inherit and include.

Other non YAML-based items which can be in a light module:

Creating a light module with Magnolia CLI

Using the Magnolia CLI you can create the folder structure for a light module with the command create-light-module. Open a shell, cd to your light modules directory, and execute the following command:

mgnl create-light-module one-pager-module

When creating a name for a module, do not use spaces, accented characters such as é, à, ç, ä, ö, ü or special characters (e.g. slashes /, \ and so on). The name must match the regular expression [a-zA-Z0-9-_].

This only works if you have installed Magnolia CLI, see Magnolia CLI Installation.
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