Hystrix-clj hello world

core.clj

(ns hystrix-hello-world.core
  (:require
   ;; hystrix
   [com.netflix.hystrix.core :as hystrix]
   [hystrix-event-stream-clj.core :as hystrix-event]

   ;; http
   [aleph.http :refer [start-http-server wrap-ring-handler]]
   [clj-http.client :as http])
  (:import [com.netflix.hystrix
            HystrixCommandProperties]))

;; Instructions to run Hystrix Dashboard (on different JVM process):
;; https://github.com/Netflix/Hystrix/tree/master/hystrix-dashboard#run-via-gradle
;; (no need to install gradle yourself, the command in there does that for you)

;; This is an example of simple command that hits
;; a remote URL
(hystrix/defcommand fetch-request
  {:hystrix/group-key "Web"
   :hystrix/command-key "URLFetch"
   :hystrix/init-fn
   (fn fetch-request-init [_ setter]
     (.andCommandPropertiesDefaults
      setter
      (.withExecutionTimeoutInMilliseconds
       (HystrixCommandProperties/Setter)
       (* 10 1000)))
     setter)
   ;; :hystrix/fallback-fn
   ;; (fn fetch-request-fallback [url]
   ;;   {:status 999
   ;;    :headers {}
   ;;    :body "shit just timed out"})

   }
  [url]
  (http/get url))
  
;; DOCUMENTATION on how hystrix defcommand works:
;; https://github.com/Netflix/Hystrix/blob/master/hystrix-contrib/hystrix-clj/src/main/clojure/com/netflix/hystrix/core.clj#L17

(defn hystrix-stream-app [req]
  (hystrix-event/stream))
  
(defn -main []
  (start-http-server
    (wrap-ring-handler hystrix-stream-app)
    {:port 4500}))

project.clj

(defproject hystrix-hello-world "0.1.0-SNAPSHOT"
  :description "FIXME: write description"
  :url "http://example.com/FIXME"
  ;; TODO: Change this
  :license {:name "Eclipse Public License"
            :url "http://www.eclipse.org/legal/epl-v10.html"}
  :repl-options { :host "0.0.0.0"
                  :port 56789 }
  :plugins [[cider/cider-nrepl "0.9.0-SNAPSHOT"]]
  :dependencies [[org.clojure/clojure "1.6.0"]
                 [clj-http "1.1.0"]
                 [aleph "0.3.3"]
                 [com.netflix.hystrix/hystrix-clj "1.4.4"]
                 [hystrix-event-stream-clj "0.1.3"]
                 ])