About django-static

What it does

django_static is a Django app that enables as various template tags for better serving your static content. It basically rewrites references to static files and where applicable it does whitespace optmization of the content. By making references to static content unique (timestamp included in the name) you can be very aggressive with your cache-control settings without ever having to worry about upgrading your code and worrying about visitors using an older version.

The three template tags it enables are the following:

1. staticfile Takes the timestamp of the file, and makes a copy by symlinking as you define. You use it like this::

    <img src="{% staticfile "/images/foo.png" %}"/>
   

   and the following is rendered:

    <img src="/images/foo.123456789.png"/>
   

   ...assuming the epoch timestamp of the file is 123456789.

2. slimfile Works the same as staticfile but instead of copying the file as a symlink it actually rewrites the file and compresses it through slimmer. This of course only works for .js and .css files but it works wonderfully fast and is careful enough to not break things. The cool thing about doing this for .css files it finds all relative images inside and applies staticfile for all of them too. You use it just like staticfile:

    <script type="text/javascript"
      src="{% slimfile "/javascript/myscript.js" %}"></script>
   

3. slimcontent is used to whitespace compress content right in the template. It requires a format paramter which can be "js", "css" or "html". So, for example for some inline CSS content you do this:

    <style type="text/css">
    {% slimcontent "css" %}
    h1, h2, h3 { 
    font-face:'Trebuchet MS', Verdana, Arial; 
    }
    {% endslimcontent %}
    </style>
   

   ...and you get this:

    <style type="text/css">
    h1,h2,h3{font-face:'Trebuchet MS',Verdana,Arial}
    </style>
   

Configuration

django_static will be disabled by default. It's not until you set DJANGO_STATIC = True in your settings module that it actually starts to work for you.

By default, when django_static slims files or makes symlinks with timestamps in the filename, it does this into the same directory as where the original file is. If you don't like that you can override the save location by setting DJANGO_STATIC_SAVE_PREFIX = "/tmp/django-static"

If you, for the sake of setting up your nginx/varnish/apache2, want change the name the files get you can set DJANGO_STATIC_NAME_PREFIX = "/cache-forever" as this will make it easier to write a rewrite rule/regular expression that in nginx/varnish/apache2 deliberately sets extra aggressive caching.

Another option is to let django_static take care of setting your MEDIA_URL. You could do this:

    <img src="{{ MEDIA_URL }}{% staticfile "/foo.png" %}"/>

But if you're feeling lazy and what django_static to automatically take care of it set DJANGO_STATIC_MEDIA_URL. In settings.py:

    DJANGO_STATIC_MEDIA_URL = "http://static.example.com"

In your template:

    <img src="{% staticfile "/foo.png" %}"/>

And you get this result:

    <img src="http://static.example.com/foo.1247785534.png"/>

Advanced configuration with DJANGO_STATIC_FILE_PROXY

If you enable, in your settings, a variable called DJANGO_STATIC_FILE_PROXY you can make all static URIs that django_static generates go though one function. So that you, for example, can do something with the information such as uploading to a CDN. To get started set the config:

    DJANGO_STATIC_FILE_PROXY = 'mycdn.cdn_uploader_file_proxy'

This is expected to be the equivalent of this import statement:

    from mycdn import cdn_uploader_file_proxy

Where mycdn is a python module (e.g. mycdn.py) and cdn_uploader_file_proxy is a regular python function. Here's the skeleton for that function:

    def cdn_uploader_file_proxy(uri, **kwargs):
        return uri

Now, it's inside those keyword arguments that you get the juicy gossip about what django_static has done with the file. These are the pieces of information you will always get inside those keyword argments:

    new = False
    checked = False
    changed = False
    notfound = False

The names hopefully speak for themselves. They become True depending on what django_static has done. For example, if you change your foo.js and re-run the template it's not new but it will be checked and changed. The possibly most important keyword argument you might get is filepath. This is set whenever django_static actually does its magic on a static file. So, for example you might write a function like this:

    on_my_cdn = {}

    def cdn_uploader_file_proxy(uri, filepath=None, new=False,
                                changed=False, **kwargs):
        if filepath and (new or changed):
            on_my_cdn[uri] = upload_to_my_cdn(filepath)

        return on_my_cdn.get(uri, uri)

Using Google Closure Compiler

If you want to use the Google Closure Compiler to optimize your Javascript files you first have to download the compiler.jar file and make sure your systam can run java. Suppose you download it in /usr/local/bin, the set this variable in your settings.py file:

    DJANGO_STATIC_CLOSURE_COMPILER = '/usr/local/bin/compiler.jar'

If for some reason the compiler chokes on your Javascript it won't halt the serving of the file but it won't be whitespace optimized and the error will be inserted into the resulting Javascript file as a big comment block.

Using the YUI Compressor

The YUI Compressor is both a Javascript and CSS compressor which requires a java runtime. Just like the Google Closure Compiler, you need to download the jar file and then set something like this in your settings.py:

    DJANGO_STATIC_YUI_COMPRESSOR = '/path/to/yuicompressor-2.4.2.jar'

If you configure the Google Closure Compiler and YUI Compressor, the Google Closure Compiler will be first choice for Javascript compression.

Using the slimmer

slimmer is an all python package that is capable of whitespace optimizing CSS, HTML, XHTML and Javascript. It's faster than the YUI Compressor and Google Closure but that speed difference is due to the start-stop time of bridging the Java files.

How to hook this up with nginx

Read this blog entry on peterbe.com