What library or namespace does luminus use to set the DATABASE_URL environment variable used by migratus? I can't seem to find where it is defined.

@donyorm luminus uses cprop library - generated config.clj contains something like this:

(defstate env :start (load-config
                       :merge
                       [(args)
                        (source/from-system-props)
                        (source/from-env)])
  )

typically, you should set :database-url in your profiles.clj:

{:profiles/dev  {:env {:database-url ""
....