URLLib3 transport implementation (Extracted from HTTPX)

httpx-urllib3.md

Changelog:

• 2024-07-15: updated to support recent HTTPX versions, based on @karpetrosyan's comment.
• 2021-01 (ish): initial version

---

urllib3-transport

An HTTPCore transport that uses urllib3 as the HTTP networking backend. (This was initially shipped with HTTPX.)

When used with HTTPX, this transport makes it easier to transition from Requests to HTTPX by keeping the same underlying HTTP networking layer.

Compatible / tested with: HTTPX 0.27.x

Note: not all urllib3 pool manager options are supported here — feel free to adapt this gist to your specific needs.

Usage

Using HTTPX:

import httpx
from urllib3_transport import URLLib3Transport

with httpx.Client(transport=URLLib3Transport()) as client:
    response = client.get("https://example.org")
    print(response)

If you want to pass a custom ssl_context using the same options than HTTPX (verify, cert, trust_env), use the httpx.create_ssl_context() helper:

import httpx
from urllib3_transport import URLLib3Transport

ssl_context = httpx.create_ssl_context(verify="/tmp/client.pem")

with httpx.Client(transport=URLLib3Transport(ssl_context=ssl_context)) as client:
    response = client.get("https://example.org")
    print(response)

See also Changing the verification defaults in the HTTPX docs.

License

MIT License

Copyright (c) 2020 Florimond Manca

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

urllib3_transport.py

import typing

import httpx
import urllib3
from httpx._config import create_ssl_context
from httpx._types import CertTypes, ProxyTypes, SyncByteStream, VerifyTypes


def httpx_headers_to_urllib3_headers(headers: httpx.Headers) -> urllib3.HTTPHeaderDict:
    urllib3_headers = urllib3.HTTPHeaderDict()
    for name, value in headers.multi_items():
        urllib3_headers.add(name, value)
    return urllib3_headers


class ResponseStream(SyncByteStream):
    CHUNK_SIZE = 1024

    def __init__(self, urllib3_stream: typing.Any) -> None:
        self._urllib3_stream = urllib3_stream

    def __iter__(self) -> typing.Iterator[bytes]:
        for chunk in self._urllib3_stream.stream(self.CHUNK_SIZE, decode_content=False):
            yield chunk

    def close(self) -> None:
        self._urllib3_stream.release_conn()


class Urllib3Transport(httpx.BaseTransport):
    def __init__(
        self,
        verify: VerifyTypes = True,
        trust_env: bool = True,
        max_pools: int = 10,
        maxsize: int = 10,
        cert: CertTypes | None = None,
        proxy: ProxyTypes | None = None,
    ) -> None:
        ssl_context = create_ssl_context(cert=cert, verify=verify, trust_env=trust_env)
        proxy = httpx.Proxy(url=proxy) if isinstance(proxy, (str, httpx.URL)) else proxy

        if proxy is None:
            self._pool = urllib3.PoolManager(
                ssl_context=ssl_context,
                num_pools=max_pools,
                maxsize=maxsize,
                block=False,
            )
        elif proxy.url.scheme in ("http", "https"):
            self._pool = urllib3.ProxyManager(
                str(proxy.url.origin),
                num_pools=max_pools,
                maxsize=maxsize,
                block=False,
                proxy_ssl_context=proxy.ssl_context,
                proxy_headers=httpx_headers_to_urllib3_headers(proxy.headers),
                ssl_context=ssl_context,
            )
        elif proxy.url.scheme == "socks5":
            from urllib3.contrib.socks import SOCKSProxyManager

            username, password = proxy.auth or (None, None)

            self._pool = SOCKSProxyManager(
                proxy_url=str(proxy.url),
                num_pools=max_pools,
                maxsize=maxsize,
                block=False,
                username=username,
                password=password,
            )
        else:  # pragma: no cover
            raise ValueError(
                "Proxy protocol must be either 'http', 'https', or 'socks5'," f" but got {proxy.url.scheme!r}."
            )

    def handle_request(self, request: httpx.Request) -> httpx.Response:
        timeouts = request.extensions.get("timeout", {})

        connect_timeout = timeouts.get("connect", None)
        read_timeout = timeouts.get("read", None)

        urllib3_timeout = urllib3.Timeout(
            connect=connect_timeout,
            read=read_timeout,
        )

        response = self._pool.request(
            request.method,
            str(request.url),
            body=request.content,
            headers=httpx_headers_to_urllib3_headers(request.headers),
            redirect=False,
            preload_content=False,
            timeout=urllib3_timeout,
        )

        return httpx.Response(
            status_code=response.status,
            headers=httpx.Headers([(name, value) for name, value in response.headers.iteritems()]),
            content=ResponseStream(response),
            extensions={"urllib3_response": response},
        )

@Dao-GPT Are you able to request other URLs, without Pyiodide?

I was able to fetch example.org, although with an issue on gzip encoding (I had to enforce Accept-Encoding: text/plain in the request, may raise an issue on the HTTPX repo for this). Edit: can't reproduce w/o the urllib3 transport, so it's a potential pitfall from this updated solution. Edit: looks like decode_content=False when calling urllib3_stream.stream() solves it. I will update my gist.

  File "/home/florimond/.pyenv/versions/3.12.1/lib/python3.12/site-packages/httpx/_models.py", line 830, in iter_bytes
    decoded = decoder.decode(raw_bytes)
              ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/florimond/.pyenv/versions/3.12.1/lib/python3.12/site-packages/httpx/_decoders.py", line 80, in decode
    raise DecodingError(str(exc)) from exc
httpx.DecodingError: Error -3 while decompressing data: incorrect header check

Your error seems like a specific issue with how Pyodide / Jupyter operates... If you're making a request through a browser, CORS checks apply which could explain the error. Try applying the Mode: no-corsheader, or look for the keywords "no-cors" on a search engine. Eg [this post](https://medium.com/@cybersphere/fetch-api-the-ultimate-guide-to-cors-and-no-cors-cbcef88d371e.

@florimondmanca On my local laptop, the same issue as yours happened with the original code.

Then following your suggestion I added "decode_content=False" in urllib3_stream.stream() . The code works.

I will try to fix the issue specific to Pyodide.

Thanks.