Creating a services.yml File for Drupal 9

Learn how to add a services.yml file for your Drupal 9 site.

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Drupal 9 allows users to easily define core services and environment-specific settings within the sites/default/services.yml configuration file, eliminating the need for hacks to swap functionality. Creating or modifying this file is not required when installing a new Drupal 9 site.

Production and Pre-production Service Configurations

Drupal services.yml files may contain environment-specific settings, such as debug-mode settings, or they may be used to configure settings that are applicable to all environments, such as configuring cache contexts, or setting the cookie domain. To avoid the potential for inadvertently deploying debug configuration to production, prior to Drupal 8.2.0, Pantheon placed sites/default/services.yml in the .gitignore file, to discourage users from committing this file to the repository.

As of Drupal 8.2.0, however, services.yml was removed from .gitignore, and a new mechanism was introduced to control production vs. pre-production configuration changes. Now, in your sites/default folder, you may use services.pantheon.production.yml and services.pantheon.preproduction.yml to configure your on-Pantheon service configuration parameters for production and pre-production environments.

The table below illustrates which services file is used in which Pantheon environments:

Pantheon EnvironmentSettings Filename
Test or Liveservices.pantheon.production.yml
Dev or any Multidevservices.pantheon.preproduction.yml
All environmentsservices.yml

Create and Modify services.yml

  1. Make sure that you have updated your Drupal site to version 9.


    Drupal 8 reached end-of-life status in November 2021, and is no longer supported by Drupal. Read the official announcement on

  2. Navigate to the sites/default directory and create a new services file. Name it based on which environment you wish to configure settings for:

    • All environments: services.yml
    • Production environment: services.pantheon.production.yml
    • Pre-production environment: services.pantheon.preproduction.yml


Module specific services should be defined in a separate .yml file, located in the root directory of the respective module (e.g. sites/all/modules/module_name/

See Also

View the following resources for more information: