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The settings.php file provides the primary configuration for a Drupal site, including its database connection, file paths, and various other settings.

DrevOps ships with own streamlined version of the settings.php and services.yml files. There are also Settings unit tests that ensure that the settings apply correctly per environment.

The default Drupal scaffold's default.settings.php and files are also provided if you choose to use them instead.

The settings.php file is divided into several sections:

  1. Environment constants definitions
  2. Site-specific settings
  3. Environment detection
  4. Per-environment overrides
  5. Inclusion of generated Settings
  6. Inclusion of local settings

1. Environment constants definitions

Constants for various environments are defined here. These can be used to alter site behavior based on the active environment.

Available constants include:


These are later used to set $settings['environment'] variable, which can be used in the modules and outside scripts to target code execution to specific environments.


environment="$(drush php:eval "print \Drupal\core\Site\Settings::get('environment');")"
if echo "${environment}" | grep -q -e ci -e local; then
  # Do something only in ci, or local environments.


The DREVOPS_PROVISION_ENVIRONMENT shell variable can be utilized within post-provision custom scripts, allowing targeted code execution based on specific environments. Refer to Provision for additional information.

2. Site-specific settings

This section is used for configuring core site settings such as defining paths, ensuring security with trusted host patterns, setting performance optimizations like aggregating CSS and JS files, and specifying essential directories for Drupal's functionality.

These settings are identical for all environments.

Use per-module settings files in the /includes directory to override per-module settings, including per-environment overrides.

3. Environment detection

This section uses known per-platform mechanisms to determine in which environment the site currently runs. The result is stored in the $settings['environment'] variable.

By default, $settings['environment'] is set to ENVIRONMENT_LOCAL. This value is then overridden by the environment detection logic.


In any hosting environment, the default value of $settings['environment'] changes to ENVIRONMENT_DEV, while further refinements designate more advanced environments.

Environment detection override

It is also possible to force specific environment by setting DRUPAL_ENVIRONMENT environment variable. In this case, the environment detection will take place and will load any additional per-platform settings, but the final value of $settings['environment'] will be set to the value of DRUPAL_ENVIRONMENT variable.

This is useful in cases where a certain behaviour is required for a specific environment, but the environment detection logic does not provide it. Or as a temporary override during testing.

4. Per-environment overrides

Configurations in this section alter the site's behavior based on the environment. Out-of-the-box, DrevOps provides overrides for CI and Local environments.

You can add additional overrides for other environments as needed.

5. Inclusion of per-module settings

This section includes any additional module-specific settings from the /includes directory.

DrevOps ships with settings overrides for several popular contributed modules used in almost every project.

The per environment overrides for modules should be also placed into files in the /includes directory.

6. Inclusion of local settings

At the end of the settings.php, there is an option to include additional local settings. This allows developers to override some settings for their local environment without affecting the main configuration. Developers can copy default.settings.local.php and to settings.local.php and services.local.yml, respectively, to utilize this functionality.

Testing settings with unit tests

DrevOps provides a set of unit tests that ensure that the settings apply correctly per environment. These tests are supposed to be maintained within your project, ensuring that settings activated by specific environments and environment variables are applied accurately.

After installing DrevOps, run vendor/bin/phpunit --group=drupal_settings to run the tests for the settings provided by DrevOps.

You may simply remove these tests if you do not want to maintain them.