Enabling Solr on Drupal 8

Detailed information on using Apache Solr with Drupal 8.

Contributors: Peter Sawczynec, Christopher Matthews.

Discuss in our Forum Discuss in Slack

Apache Solr is a system for indexing and searching site content.

 Important Note

Pantheon Search derives from Solr and can perform full-text content searching in a single language.

Currently, the version of Solr on Pantheon is Apache Solr v3.6.

If your search needs include geospatial search, emojis, or multilingual search, consider OpenSolr or another alternative search.

Pantheon Search supports Search API Solr 8.x-1.x, which will reach end-of-life in December 2021. Search API Solr 8.x-1.x should continue to work as long as the Search API Pantheon module is also being used, following the installation directions below.

Before You Begin

Be sure that you:

  • Enable Solr in the Pantheon Site Dashboard: Settings > Add Ons > Apache Solr Index Server: Add.

  • Install Composer

  • Create a Composer managed site on Pantheon following the Build Tools guide, or the Composer without CI guide.


Solr on Drupal 8 requires a Composer managed workflow, as described in our Build Tools and Composer without CI guides. Since one module relies on Solarium, an external library, in addition to Composer's autoloader, we cannot support non-Composer workflows for Solr on Drupal 8. For details, see this Drupal.org issue.

Install Solr on Drupal 8

Install the Search API Pantheon Module

  1. Navigate to the project's root directory on your local computer. If you have access to Multidev, checkout a new branch from master:

    git checkout -b solr master

    Otherwise, continue from the master branch.

  2. Add the Search API Pantheon module as a required dependency:

    composer require "drupal/search_api_pantheon ~1.0" --prefer-dist
  3. You should now have the Search API Pantheon module installed along with its dependencies. Run git status to make sure you see the expected result. Commit and push the changes:

    git commit -am "Require drupal/search_api_pantheon ~1.0"
    git push origin master
    git commit -am "Require drupal/search_api_pantheon ~1.0"
    git push origin solr

Configure Solr

To configure the connection with Pantheon, set the connection mode to SFTP and complete the following steps.

Enable Modules

Enable the Search API Pantheon module via the Drupal interface. When prompted, click Continue to enable the Search API and Search API Solr modules:

Disable Drupal Core's Search Module (Optional)

If you are using Search API, then you probably will not be using Drupal Core's Search module. Uninstall the Search core module from /admin/modules/uninstall to avoid confusion in further configuration steps.

Add The Search Server

Navigate to /admin/config/search/search-api/add-server and configure the following, then click Save:

  • Server name: Pantheon

  • Backend: Solr

  • Solr Connector: Pantheon

  • Schema file: modules/search_api_solr/solr-conf/4.x/schema.xml (recommended)

You can name the server anything you want but using something like "Pantheon" is a good way to remember where the connection goes. The Search API module provides schema files for each version of Solr (4, 5, and 6). You can customize schema files by copying these examples to your own custom module and editing them. If you are just getting started, we recommend selecting the file for Solr 4.

When deploying Solr to other environments (Test/Live/Multidevs) for the first time, first navigate to your Server settings page at admin/config/search/search-api/server/pantheon/edit and click Save, so you can post the Solr schema in those environments.

Add Search Index

Navigate to admin/config/search/search-api/add-index and name your index, then choose a data source. If this is your first time using Search API, start by selecting Content as a data source. This option will index articles, basic pages, and other node types you have configured.

Select Pantheon as the server, then click Save and add fields. Add fields to be included in the index and click Done.

After adding fields the configuration, make sure the index is full by clicking Index now or by running cron.

Export Configuration

It is a best practice in Drupal 8 to export your changes to yml files. You can quickly export configuration changes via Terminus:

terminus drush site.env -- config-export -y

Replace site and env with your site name and the environment (Dev, Multidev, etc), respectively.

Search the Index

To actually search your index you will need a module like Search API Pages, which allows for the configuration of search forms on their own pages.

Solr Versions and Schemas

The version of Solr on Pantheon is Apache Solr v3.6. To accommodate this older version of Solr, use the 8.x-1.x branch of Search API Solr and its Solr 4 schema file.


The "Commit changes to Memory" feature of the Apache Solr Search module is not compatible with Solr 3.x versions.

Safely Remove Solr

The following code changes are required before Solr can be safely uninstalled and disabled:

  1. Disable the Search API Solr Search, Search API, and Pantheon Apache Solr modules.
  2. Delete all schema configurations from settings.php.
  3. Commit and deploy code changes to the Live environment.
  4. Go to Settings > Add Ons and click the Remove button for Solr.


Solr Verification Check

Because we are posting the 4.x schema to a 3.x Solr instance, the schema verification check can fail and prevent indexing. You can disable the schema check by checking the Skip schema verification box in the UI, or pulling this patch to the module.

See Also