Problem with proxies parameter in AsyncClient after update to 0.28.0

[diazdiego1]

After updating to version 0.28.1, the proxies parameter is no longer accepted in httpx.AsyncClient, resulting in the following error:

TypeError("AsyncClient.init() got an unexpected keyword argument 'proxies'")

Before this update, the proxies parameter was correctly used to configure proxies directly in the AsyncClient instance. However, with the current version, attempting to pass the proxies parameter to configure proxies results in the error mentioned above.

Steps to Reproduce:

1. Install version 0.27.2 of httpx in your virtual environment.
2. Try to use AsyncClient with the proxies parameter configured:

import httpx

proxy_config = {
    'http://': 'http://your.proxy.here',
    'https://': 'https://your.proxy.here'
}

async with httpx.AsyncClient(proxies=proxy_config) as client:
    response = await client.get('https://www.example.com')

How can I configure multiple proxies (both HTTP and HTTPS) in version 0.28.1 of httpx, considering that the proxies parameter is no longer accepted?

[ska2704]

proxies= was intentionally removed in HTTPX 0.28.0. For a mapping of destination schemes to different proxies, use mounts= with AsyncHTTPTransport instances:

import asyncio

import httpx


async def main():
    proxy_config = {
        "http://": "http://127.0.0.1:8030",
        "https://": "http://127.0.0.1:8031",
    }
    mounts = {
        scheme: httpx.AsyncHTTPTransport(proxy=proxy_url)
        for scheme, proxy_url in proxy_config.items()
    }

    async with httpx.AsyncClient(mounts=mounts) as client:
        for url in ("http://www.example.com/", "https://www.example.com/"):
            response = await client.get(url)
            response.raise_for_status()
            print(response.status_code)


asyncio.run(main())

Replace the loopback addresses with your actual proxy endpoints. The mapping keys describe the destination URL scheme; each value's URL describes the connection to the proxy. An HTTPS destination can therefore use an http:// proxy URL: HTTPX establishes a CONNECT tunnel and negotiates TLS to the destination through it.

If both schemes use the same proxy, there is no need for a mapping:

async with httpx.AsyncClient(proxy="http://127.0.0.1:8030") as client:
    response = await client.get("https://www.example.com/")

The proxy documentation shows the mounts approach with synchronous HTTPTransport; use AsyncHTTPTransport for your AsyncClient. Renaming a dictionary argument from proxies= to proxy= is not the equivalent migration: proxy= specifies a single proxy.

Verified on HTTPX 0.28.1 / Python 3.13.13 with three local checks: the removed-keyword error, separate proxy routing for HTTP and HTTPS (including CONNECT and a TLS-verified response), and one shared proxy for both schemes. Prepared and tested with Codex assistance.