Spar is an opinionated framework that makes developing and deploying single-page web apps and static websites using modern front-end technology like SASS, Haml, and Coffeescript a cinch.

We created Spar to decouple front-end development and deployment from specific backend languages like ruby, python, or Java.

Who should use Spar?

  • Developers who have completely decoupled web applications (i.e. Old New Twitter) who want to do front-end development with state of the art tools like Coffeescript and SASS independent of their backend API stack.

  • Designers who love using modern technology like SASS, Less, and Haml but don't feel comfortable running and deploying apps in frameworks like Rails or Django.

  • Anyone who needs to make simple static websites and host them as static files on S3 (i.e. for really really cheap).

Under the hood, Spar uses Rack and Sprockets to provide a powerful asset pipeline similar to Rail's asset pipeline. If you're familiar with the Rail's asset pipeline, you'll feel right at home with Spar.

What makes Spar different?

  • Intepret configuration variables in your assets. For instance, setup an api_url variable that's different for your development vs. production environments.

  • No server-side language knowledge necessary. If you know how to type a few commands into the terminal you'll be good to go.

  • Built in support for CSS, Sass, Less, HTML, Haml, Javascript, Coffeescript, Compass, Haml-Coffeescript templating, and more.

If you run into issues, please use the issues page to report them and we'll help you out.

Example Spar Applications

For your reference, and to build on top of, we've created two example applications using Spar.

The first is the quintessential TODO application as popularized by addyosmani. The second, is a bootstrap application containing some of our favorite tools to kick-start the pretty (jQuery, Backbone, and Twitter Bootstrap).

Both can be found at our spar-examples repo.

You can also see a demo of the TODO app here.


  • Ruby 1.9.2 or greater (preferably 1.9.3).

Installing Spar

$ gem install spar

If using rbenv:

$ rbenv rehash

Getting Started

Issue the following command to create a new Spar project:

$ spar new myapp
$ cd myapp
$ spar server

Your app will now be available at http://localhost:8888


Spar apps are organized into the following folders and files:

/app                      #Compiled assets that make your app
  /javascripts #Your main JS output
    application.css.sass  #Your main CSS output
    index.html.haml       #Your single, root HTML page

/static                   #File in here will be available to your application, but not managed as assets.
  /downloads              #File in here will include a 'Content-Disposition: attachment;' header if deployed to S3

/vendor                   #Put external libraries like jquery or bootstrap here

config.yml                #ENV settings for development, staging, production
README                    #your project's README


config.yml defines your project's configuration for different environments. You may define any properties you like, which are available to you in all your asset files.

These settings may be overriden on a per-environment basis for development, staging, and production like so:

  debug: true
  my_app_name: My App!
  my_api: http://localhost:8080

  debug: false

  debug: false
  compress: true

Spar respects the following known configuration options:

  • debug: true/false, includes JS files individually for easier debugging
  • digest: true/false, adds MD5 hashes to end of filenames for proper cache busting in deploys
  • compress: true/false, JS and CSS compression (uglify, and yahoo UI CSS compressor)

Asset Pipeline

All asset files in the app directory are transformed through the Spar asset pipeline. Transformation first occurs for configuration properties defined in config.yml, followed by JS/CSS asset-compilation and composition.

Configuration Property Replacement

First, configuration property substitution takes place according to your config.yml file. For instance, if your index.html.haml looks like this:

    %title [{ my_app_name }]

it transforms to become:

    %title My App!


After Spar performs configuration replacement, it then process files according to their extensions.

Inlcuded with Spar are transformations from:

  • file.html.haml => file.html
  • => file.js
  • file.css.sass => file.css
  • file.css.less => file.less

Dependency Management

Multiple Javascript (or CSS) files can be merged into a single file using the require and require_tree pre-processor directives.

If you want to serve one file, say application.js, that includes the content of multiple JS files, you may define an like so:

# This file will be compiled into application.js, which 
# will include all the files below required below

# The require directive can include individual file assets
# For instance, to include the compiled output of
#= require utils

# You can also recursively includes entire directories 
# using the require_tree directive
#= require_tree ./controllers
#= require_tree ./models
#= require_tree ./views

Stylesheet files are composed similarly, however directives should be placed in CSS/SASS comments appropriately:

/*= require buttons.css */

Deploy Directive

Most Spar apps will compile into a single application.js and application.css file, each including the deploy directive to ensure it is deployed.

If you wish to deploy additional root-level asset files, you may instruct Spar to do so by adding a deploy directive at the top of the file like so:

#= deploy

Or, in CSS:

/*= deploy */

You only need to do this for additional root-level Javascript and CSS based files, as Spar deploys all images, pages, and static files automatically.

Deploying Your Spar App

Spar supports three different deployment methods out of the box:

  • local: Deploy your app to a directory local to your computer.
  • s3: Deploy your app to an AWS S3 bucket.
  • cloudfront: Deploy your app to an AWS S3 bucket and invalidate a Cloudfront distribution.

To deploy your app, run:

spar deploy production

You can pass any environment name to the deploy command, typically staging or production.

Local Deployment

To deploy to a local directory, setup your config.yml file environments like so:

  debug: true

  deploy_strategy: local
  deploy_path: compiled/staging

  deploy_strategy: local
  deploy_path: compiled/production

The deploy_path may be either a relative path in your application or a global path on your computer.

S3 Deployment

To deploy to an S3 bucket, setup your environments like so:

  deploy_strategy: s3
  aws_key: "my_access_key"
  aws_secret: "my+super+secret+access+key"
  deploy_bucket: ""

Now Spar will dpeloy your app directly to an S3 bucket. To learn more and see how to setup an S3 bucket as a website, see the S3 Deployment Wiki Page

CloudFront Deployment

For details on Cloudfront deploys please see the Cloudfront Deployment Wiki Page

Issues & Bugs

Please use our Github issue tracker for Spar.


Spar is licensed under the terms of the MIT License, see the included LICENSE file.