Download image using requests and process it with PIL then upload to s3

download.py

def download_file(url):
    r = requests.get(url)

    if r.status_code != 200 or len(r.content) < 100:
        raise 'Download Failed'

    if re.search('\.png', url):
        file_type = 'png'
    elif re.search('\.gif', url):
        file_type = 'gif'
    else:
        file_type = 'jpg'

    filename = url[url.rfind('/'):]
    # Upload original image
    upload_s3(filename, r.content)
    # Generate thumbnail if not gif
    if file_type != 'gif':
        img_file = StringIO(r.content)
        pimg = Image.open(img_file)
        pimg.thumbnail((250, 250))

        # -------------------------------------------------------------
        # Some images are not in RGB mode.
        # Resizing them will give you a weired image
        # -------------------------------------------------------------
        if pimg.mode != 'RGB':
            pimg = pimg.convert('RGB')

        # -------------------------------------------------------------
        # This is the tricky part. Took me a long time to find
        # Need to save PIL image into a StringIO first
        # then use getvalue() function to get the file like object
        # -------------------------------------------------------------
        thumbnail = StringIO()
        if file_type == 'jpg':
            file_type = 'jpeg'
        pimg.save(thumbnail, file_type.upper())
        # Upload thumbnail
        upload_s3('thumbnail/' + filename, thumbnail.getvalue())