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

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!

CodePudding user response：

Docker is not the issue because I'm also getting similar error while using static the same way you did without a docker. I'm getting the error shown below:

[weasyprint:137] ERROR: Relative URI reference without a base URI:

So what I did is i used urlsplit to get my app url and I passed it to template so that i can use full url.

from django.utils.six.moves.urllib.parse import urlsplit

def test(request):
    scheme = urlsplit(request.build_absolute_uri(None))
    context = { 
        'host_url': f"{scheme.scheme}://{scheme.netloc}"
    }
    return render(request, 'pdf.html', context)

template

<img src="{{ host_url }}/logos/logo.jpg" alt="" />

Instead of passing host_url you can directly use your domain but using host_url it makes app dynamic and you don't have to change domain while you're in different domain or while using in local server.

CodePudding user response：

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.