nREPL over HTTP(s) with Drawbridge in 2020
Sometimes the only way to get REPL into your production application is to tunnel it over HTTP. nREPL has a transport and Ring handler for that provided by Drawbridge. Heroku has a nice but too dated guide on using nREPL with Drawbridge. I would like to fill the missing bits here.
Server
Using
[ring/ring-core "1.8.0"]
[ring/ring-jetty-adapter "1.8.0"]
[nrepl/nrepl "0.6.0"]
[nrepl/drawbridge "0.2.1"]we start Jetty and hook nREPL into it via Drawbridge:
(ns minbedrift-uav.webrepl
"Start a nREPL server over HTTP"
(:require
[drawbridge.core]
[ring.adapter.jetty :refer [run-jetty]]
[ring.middleware.keyword-params]
[ring.middleware.nested-params]
[ring.middleware.params]
[ring.middleware.session]))
(def drawbridge-handler
(-> (drawbridge.core/ring-handler)
(ring.middleware.keyword-params/wrap-keyword-params)
(ring.middleware.nested-params/wrap-nested-params)
(ring.middleware.params/wrap-params)
(ring.middleware.session/wrap-session)))
(defn -main []
(run-jetty
#(if (= "/repl" (:uri %))
(drawbridge-handler %)
{:status "OK" :body "Do something else..."})
{:port 5555, :join? true}))In practice you would run it in addition to your main API/.. and thus wanted :join? false so that the process doesn’t block on starting the REPL server.
Refer to the original Heroku Drawbridge guide for details and regarding adding authentication
Client
Lein
The simples way I have found to connect is using Leiningen:
;; project.clj
(defproject whatever "0.1.0-SNAPSHOT"
:plugins [[nrepl/drawbridge "0.2.1"]])and lein :connect http://localhost:5555/repl (the http:// is key).
clj
It should be possible to do this with clj:
clj -Sdeps '{:deps {nrepl/drawbridge {:mvn/version "0.2.1"}}}' \
-m nrepl.cmdline --transport drawbridge.client/ring-client-transport \
--connect --host localhost --port 5555but it doesn’t as of v.0.2.1, see nrepl/drawbridge#40.
(If you get instead an exception in bencode.clj then you forgot to specify the drawbridge transport and use the default bencode one.)