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nREPL over HTTP(s) with Drawbridge in 2020

 2 years ago
source link: https://blog.jakubholy.net/nrepl-over-http-with-drwabridge-in-2020/
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nREPL over HTTP(s) with Drawbridge in 2020

December 12, 2019

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

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).

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 5555

but 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.)

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