Skip to content


Subversion checkout URL

You can clone with
Download ZIP
Toolkit to simplify static media development and deployment.
Python Other

This branch is 1 commit ahead, 113 commits behind master

Fetching latest commit…

Cannot retrieve the latest commit at this time

Failed to load latest commit information.



One of the more significant development roadblocks we have relates to local vs. deployed media. Ideally all media (graphics, css, scripts) development would occur locally and not use production media. Then, when ready to deploy, the media should be pushed to production. That way there can be significant changes to media without disturbing the production web site.

The goal of mediasync is to develop locally and then flip a switch in production that makes all the media URLs point to remote media URLs instead of the local media directory. Specifically, mediasync executes the following tasks:

  • run deflate+jsmin on javascript files
  • run deflate+cssmin on css files
  • add expires headers to everything (if supported by the backend)

All code is under a BSD-style license, see LICENSE for details.



  • python >= 2.4 (with zlib)
  • django >= 1.0
  • boto >= 1.8d




Add the proper MEDIA_ROOT setting:

MEDIA_ROOT = '/path/to/media'

Additionally, replace the existing MEDIA_URL setting with:

MEDIA_URL = '/devmedia/'

MEDIA_URL is the URL that will be used in debug mode. Otherwise, the MEDIA_URL will be loaded from the backend settings.

The following settings dict must also be added:

        'BACKEND': '',

If you want to use a different media URL than that specified in settings.MEDIA_URL, you can add MEDIA_URL to the MEDIASYNC settings dict:

        'MEDIA_URL': '/url/to/media/', # becomes

Same goes for MEDIA_ROOT:

        'MEDIA_ROOT': '/path/to/media/',

mediasync supports pluggable backends. Please see below for information on the provided backends as well as directions on implementing your own.

If the client supports media expiration, all files are set to expire 365 days after the file was synced. You may override this value by adding EXPIRATION_DAYS to the MEDIASYNC settings dict.

'EXPIRATION_DAYS': 365 * 10, # expire in 10 years

The media URL is selected based on the DEBUG attribute in When True, media will be served locally instead of from S3. Sometimes it is necessary to serve media from S3 even when DEBUG is True. To force remote serving of media, set SERVE_REMOTE to True.



link and script tags are written using XHTML syntax. The rendering can be overridden by using the DOCTYPE setting. Allowed values are 'html4', 'html5', or 'xhtml'.

'DOCTYPE': 'xhtml',

For each doctype, the following tags are rendered:

<link rel="stylesheet" href="..." type="text/css" media="...">
<script type="text/javascript" charset="utf-8" src="..."></script>
<link rel="stylesheet" href="..." type="text/css" media="...">
<script src="..."></script>
<link rel="stylesheet" href="..." type="text/css" media="..." />
<script type="text/javascript" charset="utf-8" src="..."></script>


mediasync will attempt to intelligently determine if your media should be served using HTTPS. In order to use automatic SSL detection, django.core.context_processors.request must be added to TEMPLATE_CONTEXT_PROCESSORS in


The USE_SSL mediasync setting can be used to override the SSL URL detection.

'USE_SSL': True, # force HTTPS


'USE_SSL': False, # force HTTP

Some backends will be unable to use SSL. In these cases USE_SSL and SSL detection will be ignored.


mediasync now supports pluggable backends. A backend is a Python module that contains a Client class that implements a mediasync-provided BaseClient class.


'BACKEND': 'mediasync.backends.s3',

The following settings are required in the mediasync settings dict:

'AWS_KEY': "s3_key",
'AWS_SECRET': "s3_secret",
'AWS_BUCKET': "bucket_name",

Optionally you may specify a path prefix:

'AWS_PREFIX': "key_prefix",

Assuming a correct DNS CNAME entry, setting AWS_BUCKET to and AWS_PREFIX to myproject/media would sync the media directory to

Amazon allows users to create DNS CNAME entries to map custom domain names to an AWS bucket. MEDIASYNC can be configured to use the bucket as the media URL by setting AWS_BUCKET_CNAME to True.


Since files are given a far future expires header, one needs a way to do "cache busting" when you want the browser to fetch new files before the expire date arrives. One of the best and easiest ways to accomplish this is to alter the path to the media files with some sort of version string using the key prefix setting:

'AWS_PREFIX': "myproject/media/v20001201",

Given that and the above DNS CNAME example, the media directory URL would end up being Whenever you need to update the media files, simply update the key prefix with a new versioned string.

A CACHE_BUSTER settings can be added to the main MEDIASYNC settings dict to add a query string parameter to all media URLs. The cache buster can either be a value or a callable which is passed the media URL as a parameter.

'CACHE_BUSTER': 1234567890,

The above setting will generate a media path similar to:

Custom backends

You can create a custom backend by creating a Python module containing a Client class. This class must inherit from mediasync.backends.BaseClient. Additionally, you must implement two methods:

def remote_media_url(self, with_ssl):

remote_media_url returns the full base URL for remote media. This can be either a static URL or one generated from mediasync settings:

def put(self, filedata, content_type, remote_path, force=False):

put is responsible for pushing a file to the backend storage.

  • filedata - the contents of the file
  • content_type - the mime type of the file
  • remote_path - the remote path (relative from remote_media_url) to which the file should be written
  • force - if True, write file to remote storage even if it already exists

Add a reference to mediasync.urls in your main file.

urlpatterns = ('',
        url(r'^', include('mediasync.urls)),


Ignored Directories

Any directory in MEDIA_ROOT that is hidden or starts with an underscore will be ignored during syncing.

Template Tags

When referring to media in HTML templates you can use custom template tags. These tags can by accessed by loading the media template tag collection.

{% load media %}

If you'd like to make the mediasync tags global, you can add the following to your master file:

from django.template import add_to_builtins

Some backends (S3) support https URLs when the requesting page is secure. In order for the https to be detected, the request must be placed in the template context with the key 'request'. This can be done automatically by adding 'django.core.context_processors.request' to TEMPLATE_CONTEXT_PROCESSORS in


Renders the MEDIA_URL from with trailing slashes removed.

<img src="{% media_url %}/images/stuff.png">

MEDIA_URL takes an optional argument that is the media path. Using the argument allows mediasync to add the CACHE_BUSTER to the URL if one is specified.

<img src="{% media_url '/images/stuff.png' %}">

If CACHE_BUSTER is set to 12345, the above example will render as:

<img src="">


Renders a script tag with the correct include.

{% js "myfile.js" %}


Renders a <link> tag to include the stylesheet. It takes an optional second parameter for the media attribute; the default media is "screen, projector".

{% css "myfile.css" %}
{% css "myfile.css" "screen" %}


Shortcut to render as a print stylesheet.

{% css_print "myfile.css" %}

which is equivalent to

{% css "myfile.css" "print" %}

Writing Style Sheets

Users are encouraged to write stylesheets using relative URLS. The media directory is synced with S3 as is, so relative local paths will still work when pushed remotely.

background: url(../images/arrow_left.png);

Joined files

When serving media in production, it is beneficial to combine JavaScript and CSS into single files. This reduces the number of connections the browser needs to make to the web server. Fewer connections can dramatically decrease page load times and reduce the server-side load.

Joined files are specified in the MEDIASYNC dict using JOINED. This is a dict that maps individual media to an alias for the joined files.

        'styles/joined.css': ['styles/reset.css','styles/text.css'],
        'scripts/joined.js': ['scripts/jquery.js','scripts/processing.js'],

Files listed in JOINED will be combined and pushed to S3 with the name of the alias. The individual CSS files will also be pushed to S3. Aliases must end in either .css or .js in order for the content-type to be set appropriately.

The existing template tags may be used to refer to the joined media. Simply use the joined alias as the argument:

{% css_print "joined.css" %}

When served locally, template tags will render an HTML tag for each of the files that make up the joined file:

<link rel="stylesheet" href="/media/styles/reset.css" type="text/css" media="screen, projection" />
<link rel="stylesheet" href="/media/styles/text.css" type="text/css" media="screen, projection" />

When served remotely, one HTML tag will be rendered with the name of the joined file:

<link rel="stylesheet" href="" type="text/css" media="screen, projection" />

Media Path Shortcuts

In some cases, all CSS and JS files will be in their own directory. It can be a pain to write full paths from MEDIA_ROOT when they can be inferred from the type of media being used. Shortcuts can be used in template tags and the joined files configuration if the default paths to JS and CSS files are set.

'CSS_PATH': 'styles',
'JS_PATH': 'scripts',

When these paths are set, you can leave them off of the media paths in template tags. Using the above path settings, styles/reset.css and scripts/jquery.js can be referred to using:

{% css 'reset.css' %}
{% js 'jquery.js' %}


./ syncmedia

Change Log

2.0 (in progress)

  • add pluggable backends
  • settings refactor
  • allow override of settings.MEDIA_URL
  • Improvements to the logic that decides which files to sync. Safely ignore a wider variety of hidden files/directories.
  • Make template tags aware of whether the current page is SSL-secured. If it is, ask the backend for an SSL media URL (if implemented by your backend).

Thanks to Greg Taylor and Peter Sanchez for their contributions to this release.


  • add application/javascript and application/x-javascript to JavaScript mimetypes
  • break out of CSS and JS mimetypes
  • add support for HTTPS URLs to S3
  • allow for storage of S3 keys in ~/.boto configuration file

Thanks to Rob Hudson and Peter Sanchez for their contributions to this release.


Initial release.

Something went wrong with that request. Please try again.