Up to this point, we've been running the server on our computer, localhost(*). This works great while writing or developing the program because it makes testing changes fast and easy. Eventually we'll want to put it on the internet for others to see and use.
To put it on the internet, we're going to use a company called Heroku for hosting(*). They're going to run our program on a machine visible to anybody on the Internet. We will use use git to send them our program.
The advantage of using a company like Heroku is that they handle the work of actually maintaining a server. One of the disadvantages is that Heroku can be expensive, but for a little program like ours it's free.
First, we need to make a couple of changes to our app so it can interact with Heroku.
In handler.clj, we will add a couple of functions to print log messages when Heroku starts and stops the program.
(defn init []
(println "chatter is starting"))
(defn destroy []
(println "chatter is shutting down"))Then we need to add a main function. This is what Heroku will actually invoke(*) to start our program. Add this to the end of handler.clj.
(defn -main [& [port]]
(let [port (Integer. (or port (env :port) 5000))]
(jetty/run-jetty #'app {:port port :join? false})))Finally, we need to change our project.clj so it knows how to prepare our application for Heroku.
Our new project.clj should look like:
(defproject chatter "0.1.0-SNAPSHOT"
:description "clojure web app for displaying messages"
:url "http://example.com/FIXME"
:min-lein-version "2.0.0"
:dependencies [[org.clojure/clojure "1.7.0"]
[compojure "1.4.0"]
[ring/ring-defaults "0.1.5"]
[ring/ring-jetty-adapter "1.3.2"]
[hiccup "1.0.5"]
[hickory "0.5.4"]
[environ "1.0.0"]]
:plugins [[lein-ring "0.9.7"]
[lein-environ "1.0.0"]]
:ring {:handler chatter.handler/app
:init chatter.handler/init
:destroy chatter.handler/destroy}
:aot :all
:main chatter.handler
:profiles
{:dev
{:dependencies [[javax.servlet/servlet-api "2.5"]
[ring-mock "0.3.0"]]}
:production
{:ring
{:open-browser? false, :stacktraces? false, :auto-reload? false}
:env {production true}}}
:uberjar-name "chatter-standalone.jar")The ns of handler.clj should look like:
(ns chatter.handler
(:require [compojure.core :refer :all]
[compojure.route :as route]
[ring.middleware.defaults :refer [wrap-defaults site-defaults]]
[ring.middleware.params :refer [wrap-params]]
[ring.adapter.jetty :as jetty]
[hiccup.page :as page]
[hiccup.form :as form]
[ring.util.anti-forgery :as anti-forgery]
[environ.core :refer [env]]))We will still be able to start the app using lein ring server but now we can also start by entering lein run -m chatter.handler in the command line. When we start it this way, it defaults to port 5000, and you should see that in the browser. Port 3000 does not work anymore, but you see the app if you switch to 5000.
If we create a jar with lein uberjar, we can also start the app with java $JVM_OPTS -cp target/chatter-standalone.jar clojure.main -m chatter.handler
These new methods of starting the app are closer to what Heroku will use to start the app.
We also need a Procfile in the top directory containing the line web: java $JVM_OPTS -cp target/chatter-standalone.jar clojure.main -m chatter.handler
Stop the server using control-c, then restart with the command:
lein with-profile trampoline run
If the local web page still works; add and commit your changes, then merge your branch back into master. Push the master branch to github.
Now we'll deploy to heroku with the following commands:
heroku creategit push heroku masterheroku ps:scale web=1heroku open
The final command will open the browser and point it at your app on Heroku.
Try the traceroute command again against the address Heroku assigned your app:
$: traceroute obscure-brushlands-9918.herokuapp.com
traceroute to obscure-brushlands-9918.herokuapp.com (50.16.239.160), 30 hops max, 60 byte packets
1 192.168.1.1 (192.168.1.1) 15.820 ms 15.797 ms 15.773 ms
2 96.120.49.33 (96.120.49.33) 23.895 ms 25.196 ms 25.192 ms
3 te-0-2-0-6-sur01.webster.mn.minn.comcast.net (68.85.167.145) 25.179 ms 25.168 ms 25.362 ms
4 te-0-7-0-13-ar01.crosstown.mn.minn.comcast.net (68.87.174.189) 30.743 ms 31.979 ms te-0-7-0-12-ar01.crosstown.mn.minn.comcast.net (69.139.219.129) 31.979 ms
5 pos-0-0-0-0-ar01.roseville.mn.minn.comcast.net (68.87.174.194) 31.967 ms * *
6 he-1-12-0-0-cr01.350ecermak.il.ibone.comcast.net (68.86.94.77) 39.269 ms 25.568 ms 26.422 ms
7 be-10206-cr01.newyork.ny.ibone.comcast.net (68.86.86.225) 45.276 ms 63.727 ms 66.090 ms
8 he-0-11-0-0-pe03.111eighthave.ny.ibone.comcast.net (68.86.83.98) 58.386 ms 58.374 ms 58.358 ms
9 as16509-3-c.111eighthave.ny.ibone.comcast.net (50.242.148.118) 56.143 ms 58.280 ms 65.988 ms
10 54.240.229.76 (54.240.229.76) 65.977 ms 54.240.229.82 (54.240.229.82) 65.982 ms *
11 54.240.228.190 (54.240.228.190) 65.874 ms 54.240.228.202 (54.240.228.202) 65.888 ms 54.240.228.196 (54.240.228.196) 65.969 ms
12 54.240.229.223 (54.240.229.223) 42.112 ms 54.240.229.200 (54.240.229.200) 45.620 ms 54.240.229.221 (54.240.229.221) 47.673 ms
13 54.240.228.173 (54.240.228.173) 47.630 ms 54.240.228.177 (54.240.228.177) 52.382 ms 54.240.228.173 (54.240.228.173) 45.498 ms
14 72.21.220.100 (72.21.220.100) 52.589 ms 72.21.220.116 (72.21.220.116) 52.527 ms 54.240.228.139 (54.240.228.139) 50.825 ms
15 72.21.220.135 (72.21.220.135) 56.875 ms 72.21.220.167 (72.21.220.167) 59.011 ms 72.21.220.151 (72.21.220.151) 59.014 ms
16 72.21.220.108 (72.21.220.108) 48.813 ms 205.251.245.242 (205.251.245.242) 49.425 ms 48.614 ms
17 * * *
18 * * *
19 * * *
20 216.182.224.85 (216.182.224.85) 55.704 ms 216.182.224.223 (216.182.224.223) 66.895 ms 216.182.224.227 (216.182.224.227) 54.629 ms
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 * * *
28 * * *
29 * * *
30 * * *
Try going to each other's app.
To delete the app from Heroku, select the app in the dash board, click settings, delete app is on the bottom. Then,git remote remove heroku in the command line.