Getting Started

Create a new project with Leiningen.

$ lein new hello-world
$ cd hello-world

Add ring-core and ring-jetty-adapter as dependencies in project.clj.

The latest version is:

(defproject hello-world "1.0.0-SNAPSHOT"
  :description "FIXME: write"
  :dependencies [[org.clojure/clojure "1.10.1"]
                 [ring/ring-core "1.8.2"]
                 [ring/ring-jetty-adapter "1.8.2"]])

Download dependencies.

$ lein deps

Next, edit src/hello-world/core.clj and add a basic handler.

(ns hello-world.core)

(defn handler [request]
  {:status 200
   :headers {"Content-Type" "text/html"}
   :body "Hello World"})

Now we're ready to connect the handler to an adapter. Start an interactive REPL using Leiningen.

$ lein repl

Then at the REPL, run the Jetty adapter with your handler.

=> (use 'ring.adapter.jetty)
=> (use 'hello-world.core)
=> (run-jetty handler {:port 3000
                       :join? false})

A web server will now be running at: http://localhost:3000/.

It's a good idea to set the :join? option to false in REPLs — otherwise, the Jetty server will block the thread and the REPL won't process input anymore.

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