Clojurians Log v2

yes. For some reason, having #".*" caused a null pointer exception

Well, #".*" is what we have so I doubt that was the cause of your NPE.

Specifically, here's the code we have in production:

(let [h (ring-cors/wrap-cors handler
                               :access-control-allow-headers #{"accept"
                                                               "authorization"
                                                               "content-type"
                                                               "origin"}
                               :access-control-allow-methods [:delete :get
                                                              :patch :post :put]
                               ;; 24 hours (in seconds) -- note that only Firefox
                               ;; will honor this; other browsers cap lower!
                               :access-control-max-age "86400"
                               :access-control-allow-origin #".*")]
  ...)

(the ... part returns (fn [req] ...) and inside that it calls (h req) and handles the result)