Convert the specification of allowed tags, attributes, etc. for Python's Bleach module, into a list that CKEditor understands. This is useful because, if you don't tell CKEditor what tags it can use, it will likely use ones you don't want to allow through.

ckbleach.py

import StringIO
 
def allowed_content(tags, attributes={}, styles=()):
    """
    Given a list of allowed tags, dict of allowed attributes, and list of
    allowed styles, generates a CKEditor 'allowedcontent' string.  The default
    lists used by the bleach module are:  bleach.ALLOWED_TAGS, 
    bleach.ALLOWED_ATTRIBUTES, and bleach.ALLOWED_STYLES (which is empty by
    default).  This function's defaults are all empty lists/dicts.
    
    CKEditor also allows setting what CSS classes are allowed, but
    this function doesn't support that yet.
    
    http://docs.ckeditor.com/#!/guide/dev_allowed_content_rules
    
    
    >>> allowed_content(['a', 'h1'])
    'a;h1;'
    >>> allowed_content(['a', 'h1'], {'a': ('href',)})
    'a[href];h1;'
    >>> allowed_content(['a', 'h1'], styles=('color', 'background-color'))
    'a{color,background-color};h1{color,background-color};'
    """ 
    allowed = StringIO.StringIO()
        
    for tag in tags:
        allowed.write(tag)
        if tag in attributes:
            allowed.write('[')
            allowed.write(",".join(attributes[tag]))
            allowed.write(']')
        if styles:
            allowed.write('{')
            allowed.write(",".join(styles))
            allowed.write('}')
    
        allowed.write(';')
 
    return allowed.getvalue()
 
if __name__ == "__main__":
    import doctest
    doctest.testmod()