configuration split

Drupal configuration is normally changed or removed through the configuration import and export process. For example, the process I follow is to make the change in the configuration locally, export the configuration into the source code, deploy the source code to a remote server and import the configuration. Using this mechanism, configuration changes that were exported locally are imported into the site and are ready to use.

There are certain situations where using update hooks to update the configuration is necessary. This means that you would change the configuration in your system directly using code in update hooks, rather than following the export and import process. These situations are rare, but necessary from time to time in order to maintain a consistent configuration on your site.

I recently wrote a post about setting up a multi-site configuration setup using the Configuration Split module. That post was written after I did research into how to set up configuration splits and use them to create multi-site setups in Drupal. One thing I realised when doing that research was that although it's quite easy to get setup with that kind of setup, it's also easy to get it wrong and create a setup that really doesn't work.

Setting up a Drupal 8 site for a multi-site environment with a common configuration isn't too hard, it just requires a little bit of forethought and some planning to get things right. You need to have a default configuration in mind, and then think about how each site can override this configuration in different ways. I have seen it done wrong a few times recently and once you go down the wrong path, getting things back in line again can be a difficult.

The default configuration covers things like content types, vocabularies, fields, views, enabled modules, or anything else that would make up the structure of the site. Each sub-site would override this by adding configuration for theme components, custom block placement, or anything else that is custom to that site.