v2.0 Roadmap#


We’re seeking sponsors and supporters for urllib3 v2.0 on Open Collective. There’s a lot of work to be done for our small team and we want to make sure development can get completed on-time while also fairly compensating contributors for the additional effort required for a large release like v2.0.

Additional information available within the Sponsors and Supporters section of our documentation.

🚀 Functional API Compatibility#

We’re maintaining 99% functional API compatibility to make the migration an easy choice for most users. Migration from v1.x to v2.x should be the simplest major version upgrade you’ve ever completed.

Most changes are either to default configurations, supported Python versions, and internal implementation details. So unless you’re in a specific situation you should notice no changes! 🎉

v1.26.x Security and Bug Fixes#

Thanks to support from Tidelift we’re able to continue supporting v1.26.x releases with both security and bug fixes for the forseeable future 💖

If your organization relies on urllib3 and is interested in continuing support you can learn more about the Tidelift Subscription for Enterprise.

🔐 Modern Security by Default#

HTTPS requires TLS 1.2+#

Greater than 95% of websites support TLS 1.2 or above. At this point we’re comfortable switching the default minimum TLS version to be 1.2 to ensure high security for users without breaking services.

Dropping TLS 1.0 and 1.1 by default means you won’t be vulnerable to TLS downgrade attacks if a vulnerability in TLS 1.0 or 1.1 were discovered in the future. Extra security for free! By dropping TLS 1.0 and TLS 1.1 we also tighten the list of ciphers we need to support to ensure high security for data traveling over the wire.

If you still need to use TLS 1.0 or 1.1 in your application you can still upgrade to v2.0, you’ll only need to set ssl_version to the proper values to continue using legacy TLS versions.

Stop Verifying CommonName in Certificates#

Dropping support the long deprecated commonName field on certificates in favor of only verifying subjectAltName to put us in line with browsers and other HTTP client libraries and to improve security for our users.

Certificate Verification via SSLContext#

By default certificate verification is handled by urllib3 to support legacy Python versions, but now we can rely on Python’s certificate verification instead! This should result in a speedup for verifying certificates and means that any improvements made to certificate verification in Python or OpenSSL will be immediately available.

✨ Optimized for Python 3.6+#

In v2.0 we’ll be specifically be targeting CPython 3.6+ and PyPy 7.0+ (compatible with CPython 3.6) and dropping support Python versions 2.7 and 3.5.

By dropping end-of-life Python versions we’re able to optimize the codebase for Python 3.6+ by using new features to improve performance and reduce the amount of code that needs to be executed in order to support legacy versions.

🔮 Tracing#

Currently with urllib3 it’s tough to get low-level insights into what how your HTTP client is performing and what your connection information looks like. In v2.0 we’ll be adding tracing and telemetry information to HTTP response objects including:

  • Connection ID

  • IP Address resolved by DNS

  • Request Method, Target, and Headers

  • TLS Version and Cipher

  • Certificate Fingerprint, subjectAltName, and Validity Information

  • Timings for DNS, Request Data, First Byte in Response

📜 Type-Hinted APIs#

You’ll finally be able to run Mypy or other type-checkers on code using urllib3. This also means that for IDEs that support type hints you’ll receive better suggestions from auto-complete. No more confusing with **kwargs!

We’ll also add API interfaces to ensure that when you’re sub-classing an interface you’re only using supported public APIs to ensure compatibility and minimize breakages down the road.

🎁 …and many more features!#

  • Top-level urllib3.request() API

  • Open Possibility to Alternate HTTP Implementations

  • Translated Guides

  • Support Zstandard Compression

  • Streaming multipart/form-encoded Request Data

  • More Powerful and Configurable Retry Logic

If there’s a feature you don’t see here but would like to see in urllib3 v2.0, there’s an open GitHub issue for making feature suggestions.

📅 Release and Migration Schedule#

We’re aiming for all v2.x features to be released in mid-to-late 2021.

Here’s what the release and migration schedule will look like leading up to v2.0 being released:

  • Development of v2.x breaking changes starts.

  • Release v1.26.0 with deprecation warnings for v2.0.0 breaking changes. This will be the last non-patch release within the v1.x stream.

  • Release v2.0.0-alpha1 once all breaking changes have been completed. We’ll wait for users to report issues, bugs, and unexpected breakages at this stage to ensure the release v2.0.0 goes smoothly.

  • Development of remaining v2.x features starts.

  • Release v2.0.0 which will be identical to v2.0.0-alpha1.

  • Release v2.1.0 with remaining v2.x features.

Deprecation warnings within v1.26.x will be opt-in by default.

More detailed Application Migration Guide coming soon.

For Package Maintainers#

Since this is the first major release in almost 9 years some users may be caught off-guard by a new major release of urllib3. We’re mitigating this by trying to make v2.x API-compatible with v1.x.

If your application or library uses urllib3 and you’d like to be extra cautious about not breaking your users, you can pin urllib3 like so until you ensure compatibility with v2.x:

# 'install_requires' or 'requirements.txt'

We’d really appreciate testing compatibility and providing feedback on v2.0.0-alpha1 once released.