How to install a separated Civi database with Drupal 8?

Question

I am very confused with the evolution of Drupal 8 going away from its ability in Drupal 7 to easily handle multisite.

Is it still possible to share a Civi database with the multisite extension with several Drupal 8 sites?

What about sharing a CiviCRM database between a mix of Drupal 7 and Drupal 8 sites?

More globally, can a Civi database be separated from the Drupal 8 database ?

========= I had read from David Snopek while researching this question that he thought it might work to use an edited version of the file civicrm.settings.php, though hadn't actually tried because of his server policies.

So I tried integrating an additional Drupal 8 site already running with a Drupal 7 site! I edited the civicrm.settings.php in Drupal 7 site in order to adapt it to the path of the Drupal 8 site as follows:

$civicrm_root = '/PATH/SITE/public_html/sites/all/modules/civicrm';

became this :

$civicrm_root = '/PATH/SITE/public_html/vendor/civicrm/civicrm-core';

But I this error message was the result:

PHP Fatal error:  Call to undefined function variable_get() in /var/data/sites/reveal/public_html/vendor/civicrm/civicrm-core/CRM/Utils/System/Drupal.php on line 790and –-

Answer 1

I was able to separate my Drupal 8 database from my CiviCRM database fairly easily, here are my notes I took on how to do it. Note that these steps aren't particularly specific to Drupal 8, and can be used to convert any single-database install into a two-database install.

• Create a new database (e.g. "example_civi") on the same server.
• Do NOT create a separate MySQL user - just use the same MySQL user Drupal uses.
• Grant permissions to the user. Here's the permissions you need:

TABLES, CREATE TEMPORARY TABLES, TRIGGER, CREATE ROUTINE, ALTER ROUTINE,
CREATE VIEW, SHOW VIEW, REFERENCES ON ``.* TO ''@'localhost';

• Load a dump that just has CiviCRM tables into the new database. Steps to dump tables by prefix are available. Since you sound like you're potentially upgrading an existing site, you can just copy the existing database instead.

• Drop the CiviCRM tables from the Drupal database. There's a good explanation of how to remove tables by prefix.

On the last step, note that foreign key constraints will cause some tables not to delete. You'll either need to run those steps multiple times or disable FK constraints before dropping the tables.

UPDATE: See also how to enable Views integration on D8 with separated databases.

Answer 2

Jon has also answered the original question of how to install CiviCRM in its own database.

Specifically, if you add the connection information in your settings file (before installing CiviCRM), it uses that, i.e. in settings.php add in:

$databases['civicrm']['default'] = [ 'database' => 'civicrm', 'username' => 'mysqluser', 'password' => 'a-mysql-password', 'prefix' => '', 'host' => 'localhost-or-whatever', 'port' => '', 'namespace' => 'Drupal\Core\Database\Driver\mysql', 'driver' => 'mysql' ]