Core migrations are now categorized to Configuration or Content

All migrations provided by core are now categorized as 'Content' or 'Configuration' using migration_tags.

The contributed Migrate Tools module provides the capability to execute migrations using Drush. Migrate Tools can take use of the Content / Configuration tags so that the site builder can selectively execute only Content migrations or only Configuration migrations.

Being able to limit the migrations to content only is particularly useful on larger and more complex migrations where the Drupal 8 configuration is a combination of migrated configuration and manually defined configuration. The whole site configuration can be deployed from DEV to STAGING after the DEV environment is ready using the Configuration Management capabilities. On STAGING and PROD environments, we only want to execute the content migrations to import the content from the source site.

drush migrate:import --tag=Configuration

drush migrate:import --tag=Content

Impact to migrations provided by contributed modules

Contributed modules that provide migrations should categorize all migrations to either 'Content' or 'Configuration' using migrate_tags. The following example has two migration_tags, 'Drupal 6' and the new 'Configuration' tag.

migration_tags:
  - Drupal 6
  - Configuration