updated atom value not used in compojure route - clojure

Question

I have a (routes (route/not-found)) definition with value derived from an (atom). Though I've updated the atom, the routing retains the initial value. This is similiar to Dynamic handler update in Clojure Ring/Compojure REPL but I'm having a hard time understanding what needs to be de/referenced where.
(ns mveroute
(:require
[org.httpkit.server :as srv]
[compojure.core :as cmpj]
[compojure.route :as route]
[clj-http.client :as client])
(:gen-class))
(def my-atom (atom "foobar"))
(def app
(cmpj/routes
(route/not-found {:status 400 :body #my-atom})))
(defn -main [& args]
(reset! my-atom "hello world")
(srv/run-server #'app {:port 8005})
;; "hello world" as expected
(println #my-atom)
;; still "foobar" but wanted "hello world"
(-> "http://localhost:8005"
(client/get {:throw-exceptions? false})
:body
println))
I thought warp-routes might have come to the rescue. But not how I've used it.
(defn atom-body [] {:status 200 :body #my-atom})
(cmpj/defroutes wrap-found
(route/not-found (atom-body)))
(def app
(cmpj/wrap-routes #'wrap-found {}))
The ultimate goal is a simple cli application that can set the resource/html root directory with command line arguments.

Answer 1

Try something like the following:
(defn not-found-fn
[req]
{:status 400 :body "not found again!"})
(def app
(cmpj/routes
(route/not-found not-found-fn)))
So inside of not-found-fn, you can construct the :body string any way you like. You could also have the string stored in an atom which is dereferenced by not-found-fn.
Side note:
Please see the following to clarify when you should use a Var object instead of just a symbol in your code:
When to use a Var instead of a function?