Weasyprint failed to load image at url: Name or service not known

I am working with weasyprint after I migrated from xhtml2pdf, and I am finding some issue with getting static files. I get the following error:

2021-12-03 14:45:50,198 [ERROR] Failed to load image at "http://api.dashboard.localhost:8000/static/logos/logo.png" (URLError: <urlopen error [Errno -2] Name or service not known>)

but when I access the same URL weasyprint couldn't, either on my browser or curl, I am able to view/ access the file.

Here is my code:

from io import BytesIO
import mimetypes
from pathlib import Path
from urllib.parse import urlparse
import logging

from django.conf import settings
from django.contrib.staticfiles.finders import find
from django.core.files.storage import default_storage
from django.urls import get_script_prefix
from django.template.loader import render_to_string
import weasyprint
from weasyprint import HTML


logging.basicConfig(
    level=logging.INFO,
    format="%(asctime)s [%(levelname)s] %(message)s",
    handlers=[
        logging.FileHandler("debug.log"),
        logging.StreamHandler()
    ]
)

# https://github.com/fdemmer/django-weasyprint/blob/main/django_weasyprint/utils.py
def url_fetcher(url, *args, **kwargs):
    # load file:// paths directly from disk
    if url.startswith('file:'):
        mime_type, encoding = mimetypes.guess_type(url)
        url_path = urlparse(url).path
        data = {
            'mime_type': mime_type,
            'encoding': encoding,
            'filename': Path(url_path).name,
        }

        default_media_url = settings.MEDIA_URL in ('', get_script_prefix())
        if not default_media_url and url_path.startswith(settings.MEDIA_URL):
            media_root = settings.MEDIA_ROOT
            if isinstance(settings.MEDIA_ROOT, Path):
                media_root = f'{settings.MEDIA_ROOT}/'
            path = url_path.replace(settings.MEDIA_URL, media_root, 1)
            data['file_obj'] = default_storage.open(path)
            return data

        elif settings.STATIC_URL and url_path.startswith(settings.STATIC_URL):
            path = url_path.replace(settings.STATIC_URL, '', 1)
            data['file_obj'] = open(find(path), 'rb')
            return data

    # fall back to weasyprint default fetcher
    return weasyprint.default_url_fetcher(url, *args, **kwargs)


def render_template_to_pdf(template_path, request, context):
    results = BytesIO()
    template_string = render_to_string(
        template_name=template_path,
        context=context,
    )
    # create the pdf report
    HTML(string=template_string, base_url=request.build_absolute_uri("/"), url_fetcher=url_fetcher).write_pdf(results)
    return results.getbuffer()

The above code generates the pdf, but with no images as the above mentioned error keeps showing in my logs.

My settings for media/ static files:

DEFAULT_FILE_STORAGE = "utils.storages.CustomFileSystemStorage"
STATIC_URL = "/static/"
STATIC_ROOT = os.path.realpath(env.str("STATIC_FILES_ROOT", default=os.path.join(BASE_DIR, "staticfiles") + "/"))
MEDIA_URL = "/media/"
MEDIA_ROOT = os.path.realpath(env.str("MEDIA_FILES_ROOT", default=os.path.join(BASE_DIR, "mediafiles") + "/"))
STATICFILES_DIRS = [
    os.path.join(BASE_DIR, "static"),
]  

In my template:

{% load static %}
 
<div style="float: right;">
  <img src="{% static 'logos/logo.jpg' %}" alt="logo" width="140" height="40"/>
</div>

I am running this in docker, but I think it may not be relevant since I could access the files outside the application (browser/ curl) but not with weasyprint.

I have been checking answers on stackoverflow/github/etc but couldn't find something explaining why is this happening or how to work around it unfortunately. Any insights on why this is happening are very appreciated!

I am not sure why, but setting base_url to "." resolves the issue and weasyprint can now resolve both local and external static files.

Change takes effect in:

HTML(string=template_string, base_url=".", url_fetcher=url_fetcher).write_pdf(results)

This took me the whole day and I looked into the source code of both weasyprint and django-weasyprint before attempting the ".". I hope this saves anyone with same issue some time in the future.