A Fabric task to deploy static assets to S3, gzipping the js and css files, and invalidating cache objects on CloudFront. Feel free to point out where it could be improved.

fab deploy_static

import datetime
import arrow
from fabric.api import *
import boto
from boto.cloudfront import CloudFrontConnection
import os
from datetime import date, timedelta
import gzip
import shutil


CDN = {
    'aws_cloudfront_id': 'YOUR_CLOUDFRONT_ID',
    'aws_access_key' : 'YOUR_AWS_ACCES_KEY',
    'aws_secret_key' : 'YOUR_AWS_SECRET_KEY',
    'aws_bucket' : 'YOUR_BUCKET_NAME',
    'aws_endpoint' : 's3-eu-west-1.amazonaws.com',
    'aws_sitename' : 'YOUR_WEBSITE_NAME',  # use the domain name
    'static_folders' : [
        './img',
        './js',
        './css',
    ],
    'files': []
}

# files will live at...
# yourcdn/YOUR_WEBSITE_NAME/

@task
def deploy_static():
    """Deploys the static assets to S3"""
    require('CDN', provided_by=[prod, stage])
    if not os.path.exists('fabfile') or not os.path.isdir('fabfile'):
        abort(red("It looks like you're running the fab task from somewhere other than the project root."))
        return

    if not os.path.exists('fabfile/logs'):
        os.makedirs('fabfile/logs')

    last_run = get_last_run()
    with open('fabfile/logs/static_files_%s.log' % env.tag, 'a+') as files_log:
        files_log.seek(0)
        logged_files = [_.rstrip("\n") for _ in files_log.readlines()]
        print(blue("%s static files logged." % len(logged_files)))
        for folder in env.CDN['static_folders']:
            to_upload = len(env.CDN['files'])
            folder_to_s3(folder, logged_files, files_log, last_run)
            if len(env.CDN['files']) == to_upload:
                print(yellow('No new or modified files in %s' % folder))
        files_log.close()

    if os.path.exists('TEMP'):
        shutil.rmtree('TEMP')
    set_last_run()
    invalidate_cloudfront()


def get_last_run():
    pointer = os.path.join('fabfile', 'logs', 'static_times_%s.log' % env.tag)
    with open(pointer, 'a+') as f:
        f.seek(0)
        times = [_.rstrip("\n") for _ in f.readlines()]
        last = times[-1]
        
        try:
            l = arrow.get(last).floor('second')
        except Exception as e:
            print(red(e))
            l = arrow.get('1969-01-01').floor('second')

        f.close()

    print(yellow("Static last run: %s " % l))

    return l


def folder_to_s3(folder, logged_files, log, last_run):
        require('CDN', provided_by=[prod, stage])
        compressable = ['.css', '.js', '.svg']
        ignore_files = ['.DS_Store', '.gitkeep']
        ignore_dirs = ['projects']
        bucket = init_bucket()
        the_future = date.today() + timedelta(days=365*10)
        for path, dir, files in os.walk(folder):
            curr_dir = os.path.split(path)[1]
            for f in files:
                do_upload = False
                m = arrow.get(os.path.getmtime(os.path.join(path, f)))
                c = arrow.get(os.path.getmtime(os.path.join(path, f)))
                if os.path.join(path, f) not in logged_files:
                    if f not in ignore_files and curr_dir not in ignore_dirs:
                        print(green('NEW: %s' % os.path.join(path, f)))
                        log.write('%s\n' % os.path.join(path, f))
                        do_upload = True

                elif m.timestamp > last_run.timestamp or c.timestamp > last_run.timestamp:
                    print(green('MODIFIED: %s' % os.path.join(path, f)))
                    do_upload = True

                if do_upload is True:
                    if f not in ignore_files and curr_dir not in ignore_dirs:
                        headers = {'Expires': the_future}
                        foldername = os.path.split(folder)[1]
                        putpath = "%s/%s" % (foldername, os.path.relpath(os.path.join(path, f), folder))
                        print(blue(" - Putting %s " % putpath))
                        k = bucket.new_key(putpath)
                        print(blue(os.path.splitext(f)[1]))
                        if os.path.splitext(f)[1] in compressable:
                            print(blue(" Compressing %s " % f))
                            headers['Content-Encoding'] = 'gzip'
                            k.set_contents_from_filename(gzipit(path, f), headers=headers)
                        else:
                            k.set_contents_from_filename(os.path.join(path, f), headers=headers)
                        k.make_public()
                        env.CDN['files'].append(putpath)


def init_bucket():
    s3 = boto.connect_s3(CDN['aws_access_key'], CDN['aws_secret_key'])
    s3.host = CDN['aws_endpoint']
    bucket = s3.get_bucket(CDN['aws_bucket'])
    return bucket


def invalidate_cloudfront():
    conn = CloudFrontConnection(CDN['aws_access_key'], CDN['aws_secret_key'])
    print conn.create_invalidation_request(CDN['aws_cloudfront_id'], CDN['files'])
    print 'Invalidated cloudfront cache for ...\n%s' % '\n\t '.join(CDN['files'])
    CDN['files'] = []


def gzipit(path,file):
    fullpath = os.path.join(path,file)
    f_in = open(fullpath, 'rb').read()
    if not os.path.exists('TEMP'):
        os.makedirs('TEMP')
    f_out = gzip.open('TEMP/%s' % file, 'wb')
    f_out.write(f_in)
    f_out.close()
    return 'TEMP/%s' % file

Looks like some copy/paste errors - set_last_run() is missing entirely.