urllib3.future is as BoringSSL is to OpenSSL but to urllib3 (except support is available!)
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Wondering why and how this fork exist? Why urllib3 does not merge this, even partially? Take a peek at this article!

⚡ urllib3.future is a powerful, user-friendly HTTP client for Python.
⚡ urllib3.future goes beyond supported features while remaining compatible.
⚡ urllib3.future brings many critical features that are missing from both the Python standard libraries and urllib3:

• Async.
• Task safety.
• Thread safety.
• Happy Eyeballs.
• Connection pooling.
• Unopinionated about OpenSSL.
• Client-side SSL/TLS verification.
• Highly customizable DNS resolution.
• File uploads with multipart encoding.
• DNS over UDP, TLS, QUIC, or HTTPS. DNSSEC protected.
• Helpers for retrying requests and dealing with HTTP redirects.
• Automatic Keep-Alive for HTTP/1.1, HTTP/2, and HTTP/3.
• Support for gzip, deflate, brotli, and zstd encoding.
• Support for Python/PyPy 3.7+, no compromise.
• Automatic Connection Upgrade / Downgrade.
• Early (Informational) Responses / Hints.
• HTTP/1.1, HTTP/2 and HTTP/3 support.
• WebSocket over HTTP/2+ (RFC8441).
• Proxy support for HTTP and SOCKS.
• Post-Quantum Security with QUIC.
• Detailed connection inspection.
• HTTP/2 with prior knowledge.
• Multiplexed connection.
• Mirrored Sync & Async.
• Trailer Headers.
• Amazingly Fast.
• WebSocket.

urllib3.future is powerful and easy to use:

>>> import urllib3
>>> pm = urllib3.PoolManager()
>>> resp = pm.request("GET", "https://httpbin.org/robots.txt")
>>> resp.status
200
>>> resp.data
b"User-agent: *\nDisallow: /deny\n"
>>> resp.version
20

or using asyncio!

import asyncio
import urllib3

async def main() -> None:
    async with urllib3.AsyncPoolManager() as pm:
        resp = await pm.request("GET", "https://httpbin.org/robots.txt")
        print(resp.status)  # 200
        body = await resp.data
        print(body)  # # b"User-agent: *\nDisallow: /deny\n"
        print(resp.version)  # 20

asyncio.run(main())

Installing

urllib3.future can be installed with pip:

$ python -m pip install urllib3.future

You either do

import urllib3

Or...

import urllib3_future

Or... upgrade any of your containers with...

FROM python:3.12

# ... your installation ...
RUN pip install .
# then! (after every other pip call)
RUN pip install urllib3-future

Doing import urllib3_future is the safest option if you start a project from scratch for you as there is a significant number of projects that require urllib3.

Notes / Frequently Asked Questions

• It's a fork

⚠️ Installing urllib3.future shadows the actual urllib3 package (depending on installation order). The semver will always be like MAJOR.MINOR.9PP like 2.0.941, the patch node is always greater or equal to 900.

Support for bugs or improvements is served in this repository. We regularly sync this fork with the main branch of urllib3/urllib3 against bugfixes and security patches if applicable.

• Why replacing urllib3 when it is maintained?

Progress does not necessarily mean to be a revisionist, first we need to embrace what was graciously made by our predecessors. So much knowledge has been poured into this that we must just extend it.

We attempted to participate in urllib3 development only to find that we were in disagreement on how to proceed. It happens all the time, even on the biggest projects out there (e.g. OpenSSL vs BoringSSL or NSS or LibreSSL...)

• OK, but I got there because I saw that urllib3 was replaced in my environment!

Since Forks are allowed (fortunately for us); It how package manager do things.

We know how sensible this matter is, this is why we are obligated to ensure the highest level of compatibility and a fast support in case anything happen. We are probably going to be less forgiven in case of bugs than the original urllib3. For good~ish reasons, we know.

The matter is taken with utmost seriousness and everyone can inspect this package at will.

We regularly test this fork against the most used packages (that depend on urllib3, especially those who plunged deep into urllib3 internals).

Finally, rare is someone "fully aware" of their transitive dependencies. And "urllib3" is forced into your environments regardless of your preferences.

• Wasn't there any other solution than having an in-place fork?

We assessed many solutions but none were completely satisfying. We agree that this solution isn't perfect and actually put a lot of pressure on us (urllib3-future).

Here are some of the reasons (not exhaustive) we choose to work this way:

A) Some major companies may not be able to touch the production code but can "change/swap" dependencies.

B) urllib3-future main purpose is to fuel Niquests, which is itself a drop-in replacement of Requests. And there's more than 100 packages commonly used that plug into Requests, but the code (of the packages) invoke urllib3 So... We cannot fork those 100+ projects to patch urllib3 usage, it is impossible at the moment, given our means. Requests trapped us, and there should be a way to escape the nonsense "migrate" to another http client that reinvent basic things and interactions.

C) We don't have to reinvent the wheel.

D) Some of our partners started noticing that HTTP/1 started to be disabled by some webservices in favor of HTTP/2+ So, this fork can unblock them at (almost) zero cost.

• OK... then what do I gain from this?

1. It is faster than its counterpart, we measured gain up to 2X faster in a multithreaded environment using a http2 endpoint.
2. It works well with gevent / does not conflict. We do not use the standard queue class from stdlib as it does not fit http2+ constraints.
3. Leveraging recent protocols like http2 and http3 transparently. Code and behaviors does not change one bit.
4. You do not depend on the standard library to emit http/1 requests, and that is actually a good news. http.client has numerous known flaws but cannot be fixed as we speak. (e.g. urllib3 is based on http.client)
5. There a ton of other improvement you may leverage, but for that you will need to migrate to Niquests or update your code to enable specific capabilities, like but not limited to: "DNS over QUIC, HTTP" / "Happy Eyeballs" / "Native Asyncio" / "Advanced Multiplexing".
6. Non-blocking IO with concurrent streams/requests. And yes, transparently.
7. It relaxes some constraints established by upstream in their version 2, thus making it easier to upgrade from version 1.

• Is this funded?

Yes! We have some funds coming in regularly to ensure its sustainability.

• How can I restore urllib3 to the "legacy" version?

You can easily do so:

# remove both
python -m pip uninstall -y urllib3 urllib3-future
# reinstate legacy urllib3
python -m pip install urllib3

OK! How to let them both?

# remove both
python -m pip uninstall -y urllib3 urllib3-future
# install urllib3-future
python -m pip install urllib3-future
# reinstate legacy urllib3
python -m pip install urllib3

The order is (actually) important.

Super! But how can I do that when installing something that requires somewhere urllib3-future?

Let's say you want to install Niquests and keep BOTH urllib3 and urllib3-future, do:

URLLIB3_NO_OVERRIDE=true pip install niquests --no-binary urllib3-future

This applies to every package you wish to install and brings indirectly urllib3-future.

• Can you guarantee us that everything will go smooth?

Guarantee is a strong word with a lot of (legal) implication. We cannot offer a "guarantee". But, we answer and solve issues in a timely manner as you may have seen in our tracker.

We take a lot of precaution with this fork, and we welcome any contribution at the sole condition that you don't break the compatibility between the projects. Namely, urllib3 and urllib3-future.

Every software is subject to bugs no matter what we do.

This being said, rest assured, we kept all the tests from urllib3 to ensure that what was guaranteed by upstream is also carefully watched down there. See the CI/pipeline for yourself.

In addition to that, we enforced key integration tests to watch how urllib3-future act with some critical projects.

Top-priorities issues are those impacting users with the "shadowing" part. Meaning, if a user is suffering an error or something that ends up causing an undesirable outcome from a third-party library that leverage urllib3.

• Can I contribute to this?

Yes! But keep in mind that it is going to be hard to contribute as we have huge constraints. Some of them: Python 3.7+, OpenSSL <1.1.1,>1, LibreSSL, Downstream Perfect Compat, API Compatibility with urllib3, and so on.

If you like a good challenge, then this project will definitely suit you.

Make sure everything passes before submitting a PR, unless you need guidance on a specific topic.

After applying your patch, run (Unix, Linux):

./ci/run_legacy_openssl.sh
./ci/run_legacy_libressl.sh
./ci/run_dockerized.sh
nox -s test-3.11

replace the 3.11 part in test-3.11 by your interpreter version.

If the tests all passes, then it is a firm good start.

Complete them with:

nox -s downstream_requests
nox -s downstream_niquests
nox -s downstream_boto3
nox -s downstream_sphinx

Finally make sure to fix any lint errors:

nox -s lint

• OS Package Managers, beware!

Fellow OS package maintainers, you cannot just build and ship this package to your package registry. As it override urllib3 and due to its current criticality, you'll have to set:

URLLIB3_NO_OVERRIDE=true python -m build. Set URLLIB3_NO_OVERRIDE variable with "true" in it.

It will prevent the override.

Compatibility with downstream

You should always install the downstream project prior to this fork. It is compatible with any program that use urllib3 directly or indirectly.

e.g. I want requests to be use this package.

python -m pip install requests
python -m pip install urllib3.future

Nowadays, we suggest using the package Niquests as a drop-in replacement for Requests. It leverages urllib3.future capabilities appropriately.

Testing

To ensure that we serve HTTP/1.1, HTTP/2 and HTTP/3 correctly we use containers that simulate a real-world server that is not made with Python.

Although it is not made mandatory to run the test suite, it is strongly recommended.

You should have docker installed and the compose plugin available. The rest will be handled automatically.

python -m pip install nox
nox -s test-3.11

The nox script will attempt to start a Traefik server along with a httpbin instance. Both Traefik and httpbin are written in golang.

You may prevent the containers from starting by passing the following environment variable:

TRAEFIK_HTTPBIN_ENABLE=false nox -s test-3.11

Documentation

urllib3.future has usage and reference documentation at urllib3future.readthedocs.io.

Contributing

urllib3.future happily accepts contributions.

Security Disclosures

To report a security vulnerability, please use the GitHub advisory disclosure form.

Sponsorship

If your company benefits from this library, please consider sponsoring its development.