Last updated April 8, 2015. Created on May 21, 2013.
Edited by sidharrell, oadaeh, batigolix, george.plescan. Log in to edit this page.

Main topic described: project metadata

An essential part of a Drupal 8 module, theme, or install profile is the .info.yml file (aka, "info yaml file") to store metadata about the project.

These .info.yml files are required to:

  • Notify Drupal about the existence of a module, theme, or install profile.
  • Provide information for the Drupal Web UI administration pages.
  • Provide criteria to control module activation and deactivation and Drupal version compatibility.
  • General administrative purposes in other contexts.

Hello World

The following is the hello_world.info.yml file that we will be using. If you are following along, go ahead and create a new file, called hello_world.info.yml, in your module's root folder, and paste this code into it:

name: Hello World Module
description: Creates a page showing "Hello World".
package: Custom
type: module
version: 1.0
core: 8.x

Looking at the info.yml file above lets take a look at each line to see what it does.

The first three lines are primarily used in the administration UI when allowing users to enable or disable your module. The name and description (both required) keys provide the text that is shown on the module administration page and the package key allows you to group like modules together. Core, for example, uses package: Core to group all of the modules provided with Drupal 8 together, likewise you might use package: Custom to group all of your projects custom modules together making them easier to locate and enable.

The type key, which is new in Drupal 8, is required and indicates the type of extension, e.g. module, theme or profile.

For modules hosted on drupal.org, the version number will be filled in by the packaging script, you should not specify it manually, but leave out the version line entirely.

The core key is required and specifies the version of Drupal core that your module is compatible with.

In addition to the properties shown in the example you can also specify hidden: true which will hide your module from the module list on the Extend page (/admin/modules). You might find it useful to hide a module if, for example, it only contains tests for the testing framework to use, or it is a sub-module that's only intended to serve as an example for developers who need to implement the main module's API. To avoid clutter on the Modules list, you can choose to hide them.

Debugging .info.yml files

Module is not listed on admin/modules

  • Ensure the info file is named {machine name}.info.yml and is located in the root of the module directory.
  • Ensure that the file has the line:
    type: module
  • Ensure the module name starts either with a letter or an underscore. Excerpt from the PHP documentation:

    Function names follow the same rules as other labels in PHP. A valid function name starts with a letter or underscore, followed by any number of letters, numbers, or underscores. As a regular expression, it would be expressed thus: [a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*.

Module is listed on admin/modules but its checkbox is disabled.

  • Make sure that the core compatibility is set to 8.x:
    core: 8.x
  • Ensure that all the module dependencies are available. You can expand the module information to see which requirements are missing:
    expand_requirements.png
    Note that some modules have been moved out of Drupal 8 core, whereas other contributed modules have been moved into core or replaced by new core modules.

Module description is empty

  • Remember that the description key is required.
    description: Example Module description.

See also

Looking for support? Visit the Drupal.org forums, or join #drupal-support in IRC.