Migrators

What is this?

A migrator class listens for the status of a particular feature in the feature table, and responds to the preparing state by taking some necessary data migration action. This might mean rewriting an old data format to a new format, or tweaking a configuration from a legacy system to fit a new configuration scheme.

The name comes from the analogy with database migrations.

Why are they here?

Migrators are segregated in their own directory because they are intrinsically temporary code: after a safe number of releases have passed, we may retire them.

This enables adding & removing migrators without disrupting the areas of code they migrate data on behalf of.