Convert HTML to a self contained file with inline Base64 encoded PNG images

standalone_html.py

#!/usr/bin/env python
# A simple script to suck up HTML, convert any images to inline Base64
# encoded format and write out the converted file.
#
# Usage: python standalone_html.py <input_file.html> <output_file.html>
#
# TODO: Consider MHTML format: https://en.wikipedia.org/wiki/MHTML

import os
from bs4 import BeautifulSoup


def guess_type(filepath):
    """
    Return the mimetype of a file, given it's path.

    This is a wrapper around two alternative methods - Unix 'file'-style
    magic which guesses the type based on file content (if available),
    and simple guessing based on the file extension (eg .jpg).

    :param filepath: Path to the file.
    :type filepath: str
    :return: Mimetype string.
    :rtype: str
    """
    try:
        import magic  # python-magic
        return magic.from_file(filepath, mime=True)
    except ImportError:
        import mimetypes
        return mimetypes.guess_type(filepath)[0]

def file_to_base64(filepath):
    """
    Returns the content of a file as a Base64 encoded string.

    :param filepath: Path to the file.
    :type filepath: str
    :return: The file content, Base64 encoded.
    :rtype: str
    """
    import base64
    with open(filepath, 'rb') as f:
        encoded_str = base64.b64encode(f.read())
    return encoded_str.decode('utf-8')


def make_html_images_inline(in_filepath, out_filepath):
    """
    Takes an HTML file and writes a new version with inline Base64 encoded
    images.

    :param in_filepath: Input file path (HTML)
    :type in_filepath: str
    :param out_filepath: Output file path (HTML)
    :type out_filepath: str
    """
    basepath = os.path.split(in_filepath.rstrip(os.path.sep))[0]
    soup = BeautifulSoup(open(in_filepath, 'r'), 'html.parser')
    for img in soup.find_all('img'):
        img_path = os.path.join(basepath, img.attrs['src'])
        mimetype = guess_type(img_path)
        img.attrs['src'] = \
            "data:%s;base64,%s" % (mimetype, file_to_base64(img_path))

    with open(out_filepath, 'w') as of:
        of.write(str(soup))

if __name__ == '__main__':
    import sys
    make_html_images_inline(sys.argv[1], sys.argv[2])

If anyone is looking for a more comprehensive solution to do this, I really like the SingleFile browser extension: https://github.com/gildas-lormeau/SingleFile (there is also a commandline version https://github.com/gildas-lormeau/single-file-cli).