There are at least two Grails plugins that emulate the database migration functionality of Rails:
Is there a consensus a
There is now a standard Grails database migration plugin available. According to this blog post at least the liquibase plugin will therefore not be maintained past the liquibase 1.9 release anymore.
The new database migration plugin has built-in functionality to execute changelogs on startup and supports the definition of changes in Groovy DSL, so it's probably what you are looking for.