This is the fifth installment in a series presenting work on shared configuration that comes out of the Drutopia initiative and related efforts. To catch up, see Part 1, Configuration Providers, Part 2, Configuration Snapshots, Part 3, Respecting Customizations, and Part 4, Configuration Alters.

In this installment we'll start to pull it all together.

Paraphrasing a bit from Part 1, we described a key problem this way:

How can I update my site so that I have all the latest configuration changes from a distribution--while still retaining any customizations I made?

In Part 1 we mentioned Fabian Bircher's widely used Configuration Split module and its enabling API module, Config Filter, returning in Part 3 to give a more detailed introduction. In Part 2, we summarized the API and accompanying user interface that core provides for staging configuration. Here we'll take a deep dive into how we can merge in configuration updates from installed extensions through an approach that's built on Config Filter and closely parallels core's configuration staging.