Jake McCrary

Better code reloading in a Clojure web server

A couple weeks ago I released com.jakemccrary/reload. This tiny library provides a ring middleware that uses org.clojure/tools.namespace to reload changed Clojure code on incoming http requests.

This middleware was created because my team was running into problems using ring’s wrap-reload middleware. Unfortunately these problems happened about nine months ago and, since I didn’t write this post back then, I’ve since forgotten these problems. Regardless, this project has been used since the beginning of this year and has helped make my team’s development workflow smoother. If you are running into problems it might help you too.


If you’d like to give it a shot, then add the latest version (at the time of writing [com.jakemccrary/reload "0.1.0"]) to your project.clj.

Require com.jakemccrary.middleware.reload and wrap your handler with wrap-reload.

(ns example
   ;; more deps
   [com.jakemccrary.middleware.reload :as reload]))

;; wherever you are setting up your middleware stack
(reload/wrap-reload routes)

reload/wrap-reload optionally takes a list of directories to monitor as a second parameter. By default it reloads the src directory.

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