Clojure on Heroku with Noir and Mongo Demo

create-heroku

# Install latest version of noir.
lein install noir "1.1.0-SNAPSHOT"
# Create new noir project.
lein noir new noir-mongo-heroku
cd noir-mongo-heroku
# Create instructions for heroku.
echo 'web: lein run' > Procfile
# Create git repository.
git init
git add .
git commit -m "Initial commit"
# Initialize heroku app.
heroku create --stack cedar
# Push to heroku.
git push heroku master

dependencies

# 1. Install lein
wget https://raw.github.com/technomancy/leiningen/stable/bin/lein
sh lein
# 2. Install heroku gem
gem install heroku

heroku-addon

# Configure Heroku to add a small mongo add on for our app.
heroku addons:add mongohq:free

welcome.clj

(ns noir-heroku.views.welcome
  (:require [noir-heroku.views.common :as common]
            [noir.content.pages :as pages])
  (use noir.core
       hiccup.core
       hiccup.page-helpers)
  (:use somnium.congomongo)
  (:use [somnium.congomongo.config :only [*mongo-config*]]))

(defn split-mongo-url [url]
  "Parses mongodb url from heroku, eg. mongodb://user:pass@localhost:1234/db"
  (let [matcher (re-matcher #"^.*://(.*?):(.*?)@(.*?):(\d+)/(.*)$" url)]
    (when (.find matcher)
      (zipmap [:match :user :pass :host :port :db] (re-groups matcher)))))

(defn maybe-init []
  "Checks if connection and collection exist, otherwise initialize."
  (when (not (connection? *mongo-config*))
    (let [mongo-url (get (System/getenv) "MONGOHQ_URL")
	  config    (split-mongo-url mongo-url)]
      (println "Initializing mongo @ " mongo-url)
      (mongo! :db (:db config) :host (:host config) :port (Integer. (:port config)))
      (authenticate (:user config) (:pass config))
      (or (collection-exists? :firstcollection) 
	  (create-collection! :firstcollection)))))

(defpage "/welcome" []
  (maybe-init)
  (let [counter 
	(fetch-and-modify 
	 :firstcollection 
	 {:_id "counter"} 
	 {:$inc {:value 1} }
	 :return-new true :upsert? true)]
    (common/layout
     [:p (str "Welcome to noir-heroku, you're visitor " (:value counter))])))

wget-welcome

wget https://gist.github.com/1063814.js?file=welcome.clj -O src/noir_heroku/views/welcome.clj