Httpx

This release switches to `httpcore` for all the internal networking, which means:

* We're using the same codebase for both our sync and async clients.
* HTTP/2 support is now available with the sync client.
* We no longer have a `urllib3` dependency for our sync client, although there is still an *optional* `URLLib3Transport` class.

It also means we've had to remove our UDS support, since maintaining that would have meant having to push back our work towards a 1.0 release, which isn't a trade-off we wanted to make.

We also now have [a public "Transport API"](https://www.python-httpx.org/advanced/transports/#custom-transports), which you can use to implement custom transport implementations against. This formalises and replaces our previously private "Dispatch API".

Changed

* Use `httpcore` for underlying HTTP transport. Drop `urllib3` requirement. (Pull 804, 967)
* Rename pool limit options from `soft_limit`/`hard_limit` to `max_keepalive`/`max_connections`. (Pull 968)
* The previous private "Dispatch API" has now been promoted to a public "Transport API". When customizing the transport use `transport=...`. The `ASGIDispatch` and `WSGIDispatch` class naming is deprecated in favour of `ASGITransport` and `WSGITransport`. (Pull 963)

Added

* Added `URLLib3Transport` class for optional `urllib3` transport support. (Pull 804, 963)
* Streaming multipart uploads. (Pull 857)
* Logging via HTTPCORE_LOG_LEVEL and HTTPX_LOG_LEVEL environment variables
and TRACE level logging. (Pull encode/httpcore79)

Fixed

* Performance improvement in brotli decoder. (Pull 906)
* Proper warning level of deprecation notice in `Response.stream` and `Response.raw`. (Pull 908)
* Fix support for generator based WSGI apps. (Pull 887)
* Reuse of connections on HTTP/2 in close concurrency situations. (Pull encode/httpcore81)
* Honor HTTP/2 max concurrent streams settings (Pull encode/httpcore89, encode/httpcore90)
* Fix bytes support in multipart uploads. (Pull 974)
* Improve typing support for `files=...`. (Pull 976)

Removed

* Dropped support for `Client(uds=...)` (Pull 804)

The 0.13.0.dev2 is a *pre-release* version. To install it, use `pip install httpx --pre`.

Added

* Logging via HTTPCORE_LOG_LEVEL and HTTPX_LOG_LEVEL environment variables
and TRACE level logging. (HTTPCore Pull 79)

Fixed

* Reuse of connections on HTTP/2 in close concurrency situations. (HTTPCore Pull 81)
* When using an `app=<ASGI app>` observe neater disconnect behaviour instead of sending empty body messages. (Pull 919)

The 0.13.0.dev1 is a *pre-release* version. To install it, use `pip install httpx --pre`.

Fixed

* Passing `http2` flag to proxy dispatchers. (Pull 934)

The 0.13.0.dev0 is a *pre-release* version. To install it, use `pip install httpx --pre`.

This release switches to `httpcore` for all the internal networking, which means:

* We're using the same codebase for both our sync and async clients.
* HTTP/2 support is now available with the sync client.
* We no longer have a `urllib3` dependency for our sync client, although there is still an *optional* `URLLib3Dispatcher` class.

It also means we've had to remove our UDS support, since maintaining that would have meant having to push back our work towards a 1.0 release, which isn't a trade-off we wanted to make.

Changed

* Use `httpcore` for underlying HTTP transport. Drop `urllib3` requirement. (Pull 804)

Added

* Added `URLLib3Dispatcher` class for optional `urllib3` transport support. (Pull 804)
* Streaming multipart uploads. (Pull 857)

Fixed

* Performance improvement in brotli decoder. (Pull 906)
* Proper warning level of deprecation notice in `Response.stream` and `Response.raw`. (Pull 908)
* Fix support for generator based WSGI apps. (Pull 887)

Removed

* Dropped support for `Client(uds=...)` (Pull 804)

---

Fixed

* Resolved packaging issue, where additional files were being included.

The 0.12 release tightens up the API expectations for `httpx` by switching to private module names to enforce better clarity around public API.

All imports of `httpx` should import from the top-level package only, such as `from httpx import Request`, rather than importing from privately namespaced modules such as `from httpx._models import Request`.

Added

* Support making response body available to auth classes with `.requires_response_body`. (Pull 803)
* Export `NetworkError` exception. (Pull 814)
* Add support for `NO_PROXY` environment variable. (Pull 835)

Changed

* Switched to private module names. (Pull 785)
* Drop redirect looping detection and the `RedirectLoop` exception, instead using `TooManyRedirects`. (Pull 819)
* Drop `backend=...` parameter on `AsyncClient`, in favour of always autodetecting `trio`/`asyncio`. (Pull 791)

Fixed

* Support basic auth credentials in proxy URLs. (Pull 780)
* Fix `httpx.Proxy(url, mode="FORWARD_ONLY")` configuration. (Pull 788)
* Fallback to setting headers as UTF-8 if no encoding is specified. (Pull 820)
* Close proxy dispatches classes on client close. (Pull 826)
* Support custom `cert` parameters even if `verify=False`. (Pull 796)
* Don't support invalid dict-of-dicts form data in `data=...`. (Pull 811)

---