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An SDK for authoring Popcorn projects.

Continuing development

Development has been moved to mozilla/ This repository will continue to exist for historical purposes. If you have any patches or issues, please send them to mozilla/ Thanks!

Supported Platforms


  • Chrome stable
  • Firefox stable
  • Internet Explorer 9+
  • Safari stable


  • node v0.8 or higher
  • npm (comes with node v0.8 installer)
  • A working build environment:
    • Mac OS X - Xcode or Command Line Tools package
    • Windows - Python 2.5+ and Visual Studio 2010; specifically:
      • uninstall any and all "Microsoft Visual C++ 2010 x86/64 Redistributable" copies
      • install Microsoft Visual C++ 2010 (Express edition is fine)
      • install Microsoft Visual Studio 2010 SP1
      • install Microsoft Windows SDK v7.1
      • install Microsoft Visual C++ 2010 SP1 Compiler Update for Windows SDK v7.1
    • Linux - build-essential package on Debian/Ubuntu, or the equivalent for your distro

Environment Setup

  1. git clone --recursive
  2. cd butter
  3. npm install

Running Butter in development mode

  1. Run node server.
  2. Navigate to http://localhost:8888/ in your favourite browser.

If you want to change the bind IP or port check the Configuration section below. Run NODE_ENV=production node server.js in order to run the server in production mode.

Server Configuration

Cornfield is Popcorn Maker's back-end server system, designed to serve content to users, store their ongoing work, and publish what they've done.


There are two types of storage Cornfield needs to run:

  • A database: To store user project data, a database is required. Popcorn Maker currently supports MySQL, PostgreSQL, and Sqlite.
  • A data-blob store: To store published projects, Cornfield can use the filesystem, or Amazon's S3.


The default server configuration can be found in lib/default-config.js. To override any of these settings you can:

  1. Use environment variables e.g. (PORT=1337 node server.js)
  2. Add a file named local.json. server.js will recurse up the directory tree looking for it
  3. Use the BUTTER_CONFIG_FILE environment variable e.g. (BUTTER_CONFIG_FILE=/etc/popcorn/local.json node server.js)

Configuration Options

  • PORT the port to bind the server to

  • hostname the hostname for the server (e.g., http://localhost:8888, This must match your browser's address bar otherwise Persona login will not work

  • NODE_ENV the environment you're running the server in (e.g. development, staging, production)

  • logger settings for server logging

    • format the logging format to use. Possible values include: default, short, tiny, dev.
  • session settings for user sessions

    • secret the sessions secret (i.e., some long string)
  • staticMiddleware settings for cornfield Connect middleware

    • maxAge the max age of static assests
  • dirs settings for various directories, paths, hostnames

    • wwwRoot the server's WWW root directory (e.g., ../)
    • templates the location of templates (e.g., ../templates)
    • embedHostname [optional] the hostname URL where published embed documents are stored, if different from hostname (e.g.,
  • templates list of templates to serve. The format is as follows: <template-name>: {{templateBase}}<path/to/template/config.json>. The {{templateBase}} string will be replaced by the value in dirs.templates (e.g., "basic": "{{templateBase}}basic/config.json")

  • exportedAssets list of scripts to include in exported assets. These are things like popcorn.js or other scripts that your exported projects depend upon in order to run.

  • additionalStaticRoots list of additional roots to use.

  • database database configuration options

    • database the database name. Used by mysql and postgresql
    • username the username to use when connecting to the database. Used by mysql and postgresql
    • password the password for the username. Used by mysql and postgresql
    • options additional sequelize options. Please see the sequelize manual for the complete listing.
      • dialect the sql dialect of the database. Default is mysql, must be one of mysql, sqlite, or postgresql
      • storage the storage engine for sqlite. Default is :memory:, an in-memory db, must be a string representing a file path or :memory:
      • logging function to print sql queries to console. Default is console.log, must be a function or false
      • host hostname of the mysql or postgresql server. Default is localhost
      • port port of the mysql or postgresql server. Default is 3306
      • pool connection pooling options for mysql and postgresql. Default is none
        • maxConnections - maximum number of connections open in the pool
        • maxIdleTime - maximum time in seconds to leave an idle connection open in the pool
  • metrics [optional] metric server configuration options for a StatsD server

    • host The host to connect to. Default is localhost
    • port The port to connect to. Default is 8125
    • prefix [optional] prefix to assign to each stat name sent. If not given a default of <NODE_ENV>.butter. will be used, for example: production.butter
    • suffix [optional] suffix to assign to each stat name sent.
    • globalize [optional] boolean to add statsd as an object in the global namespace
  • publishStore a fileStore used to publish project HTML files (see fileStore below for details)

  • feedbackStore a fileStore used to publish feedback from the user as JSON (see fileStore below for details)

  • crashStore a fileStore used to publish crash reports from the user as JSON (see fileStore below for details)

  • imageStore a fileStore used to retain converted data-uri images for published projects (see the ImageStore section below for details)

The fileStore type is used to setup a backend for storing data:

  • type the type of file store to use. Possible values include local (i.e., local file system) and s3 (i.e., Amazon S3)
  • options options for the file store, which depends on the type chosen.
    • hostname the hostname to use for constructing urls if different than embedHostname
    • local options
      • root the root directory under which all exported files are placed (e.g., ./view)
      • namePrefix [optional] the path prefix to add to any filenames passed to the local file store. For example, if using "v" all filenames will become "v/"
      • nameSuffix [optional] the filename suffix to use for all filenames (e.g., ".html")
    • s3 options
    • key the AWS S3 key to use for authentication
    • secret the AWS S3 secret to use for authentication
    • bucket the AWS S3 bucket name to use for storing key/value pairs
    • namePrefix [optional] the prefix to add to any key names passed to the s3 file store. For example, if using "v" all keys will become "v/"
    • nameSuffix [optional] the suffix to add to any key names passed to the s3 file store. For example, if using ".json" all keys will end in ".json"
    • contentType [optional] the mime type to use for data written to S3. If none given text/plain is used.
    • headers [optional] any additional headers to use for data written to S3. For example, setting cache control headers with { 'Cache-Control': 'max-age=1800' }.


As part of the configuration, an imageStore should be specified to store converted data-uri images for published projects. When a project is saved, the project data is scanned for data-uris which are converted into binary blobs and stored on the server in the imageStore. Currently, there are no special checks or functionality for image store content-types. However, the only images which will be converted are jpegs and pngs. Everything else is ignored. See below for an example imageStore configuration.

Server Monitoring

Popcorn Maker supports server monitoring with New Relic. It is implemented by the newrelic npm module. Configuration is done entirely with environment variables. See the for a comprehensive list. To enable New Relic monitoring with Popcorn Maker, the following environment variable must be set:


Getting Involved

  • Chat with the Popcorn community on in the #popcorn channel. The developers hang out here on a daily basis.
  • We also have a mailing list that you can subscribe to.
  • File bugs and feature requests on our issue tracker.
  • The latest code can be found on our Github repository.
  • If you'd like to contribute code, file a ticket on our issue tracker, and link to it from your Github pull request.