shadow-cljs dev http server with conditional proxy requests

dev_server.clj

(ns my-shadow-app.dev-server
  (:require [clj-http.client :as client]
            [clojure.string :as string]
            [shadow.http.push-state :as push-state])
  (:import [org.apache.http NoHttpResponseException]))
           
(defn handler
  [{:keys [uri http-config body headers request-method] :as request}]
  (if-not (string/starts-with? uri "/api")
    (push-state/handle request)
    (try (client/request
          {:method request-method
           :url (str (:dev-server/proxy http-config) uri)
           :body body
           :headers (dissoc headers "content-length")
           :throw-exceptions false})
      (catch NoHttpResponseException e
        {:status 504
         :body (.getMessage e)}))))

shadow-cljs.edn

{...
 :dev-http
 {9000
  {...
   :handler my-shadow-app.dev-server/handler
   :dev-server/proxy "http://localhost:8000"}}}