Drupal 8's configuration system handles configuration in a unified manner. By default, Drupal stores configuration data in the database, but it can be exported to YAML files, allowing the configuration to be managed by version control. There are cases however when configuration values need to be overridden for specific purposes. Drupal 7 had the global $conf variable that was usually populated in settings.php with conditional override values for configuration. A big drawback of that system was that the overrides crept into actual configuration.

The YAML Form module is a form builder and submission manager for Drupal 8.

The primary use case for this module is to:

Build a new form or duplicate an existing template
Publish the form as a page, node, or block
Collect submissions
Send confirmations and notifications
Review submissions online
Download submissions as a CSV

uninstalling and re-enabling modules every time we have a new migration to be registered is annoying.

To solve this we're going to add some Drush commands to our custom module to do the registration without uninstalling the module.

The Configuration Installer is a installation profile that takes over the Drupal installer and allows sites to be created from existing configuration.

This is an installation profile and needs to be put in /profiles in order to work.

As time goes on, I imagine more and more contrib modules will make use of Composer dependencies. As soon as your Drupal site needs just one contrib module with Composer dependencies, your entire site needs to be managed with Composer.