farmOS module development

farmOS modules can be written to extend the capabilities of farmOS.

This document describes how to get started with farmOS module development. For detailed documentation of Drupal development more generally, refer to the guide on drupal.org.

Modules directory

Modules should be placed in the sites/all/modules directory of the server's document root. If you are using the farmOS Docker image, this will be: /var/opt/drupal/web/sites/all/modules

A good practice is to download farmOS-specific modules into modules/farm to keep them separate. You may also consider creating a modules/custom directory for custom modules that are specific to your farmOS instance.

Namespacing

A farmOS (Drupal) module must have a unique name consisting only of lowercase alphanumeric characters and underscores. This is used as a namespace throughout the module, and allows Drupal hook functions to be executed on behalf of your module.

It is best practice to prefix all farmOS-specific module names with farm_. For example, if you were to build a module that adds a new log type called irrigation, you might name it farm_irrigation. This serves to specify that this module is made to work with farmOS, and is not designed to be installed in other Drupal sites more generally.

File structure

A farmOS (Drupal) module only requires one file for it to be recognized as a module: [modulename].info.yml (where [modulename] is the module name).

This info YML file contains the module's human readable name, description, dependency declarations, and other meta information about the module. A very simple example looks like this:

mylogtype.info.yml:

name: My log type
description: Adds my new custom log type.
type: module
package: farmOS Contrib
core_version_requirement: ^9
dependencies:
  - farm:farm_entity

Other common files and directories in a module include:

  • [modulename].module - Optional PHP file for Drupal hook implementations.
  • config/install/*.yml - Configuration entities that will be installed with the module.
  • config/optional/*.yml - Optional configuration entities that will only be installed if certain dependencies are met.
  • src/* - PHP classes organized using the PSR-4 autoloading specification.
  • tests/* - Automated tests for the module.

Publishing

If you want to share your module, consider publishing the repository so that it can be downloaded and installed by other farmOS users.

It is recommended that "contributed" farmOS modules be made available as a "project" on Drupal.org. This has two benefits:

  • Projects can be included via Composer with: composer require drupal/mymodule
  • Translations can be automatically managed and downloaded from Drupal's centralized localization server: localize.drupal.org

A list of community modules that have been made available as Drupal projects can be found in the farmOS ecosystem.

License

farmOS modules that are distributed to others must be licensed under the GNU General Public License, version 2 or later. For more information about farmOS and Drupal module licensing requirements, refer to Drupal.org Licensing.