Update documentation: complete client docs for honoring proxy env vars (

aio-libs#7235)

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## What do these changes do?

* Update proxy support docs to honor `no_proxy` env
* Complete `trust_env` parameter description to honor `wss_proxy`,
`ws_proxy` or `no_proxy` env

## Are there changes in behavior for the user?

No

## Related issue number

Update docs for: aio-libs#4431

## Checklist

- [ ] I think the code is well written
- [ ] Unit tests for the changes exist
- [x] Documentation reflects the changes
- [ ] If you provide code modification, please add yourself to
`CONTRIBUTORS.txt`
  * The format is &lt;Name&gt; &lt;Surname&gt;.
  * Please keep alphabetical order, the file is sorted by names.
- [ ] Add a new news fragment into the `CHANGES` folder
  * name it `<issue_id>.<type>` for example (588.bugfix)
* if you don't have an `issue_id` change it to the pr id after creating
the pr
  * ensure type is one of the following:
    * `.feature`: Signifying a new feature.
    * `.bugfix`: Signifying a bug fix.
    * `.doc`: Signifying a documentation improvement.
    * `.removal`: Signifying a deprecation or removal of public API.
* `.misc`: A ticket has been closed, but it is not of interest to users.
* Make sure to use full sentences with correct case and punctuation, for
example: "Fix issue with non-ascii contents in doctest text files."

---------

Co-authored-by: Marcel Loop <[email protected]>
Co-authored-by: Sam Bull <[email protected]>

CHANGES/7325.doc

@@ -0,0 +1 @@
+Complete trust_env parameter description to honor wss_proxy, ws_proxy or no_proxy env

docs/client_advanced.rst

@@ -561,6 +561,8 @@ DER with e.g::
    to :class:`TCPConnector` as default, the value from
    :meth:`ClientSession.get` and others override default.
 
+.. _aiohttp-client-proxy-support:
+
 Proxy support
 -------------
 
@@ -592,14 +594,18 @@ Authentication credentials can be passed in proxy URL::
 Contrary to the ``requests`` library, it won't read environment
 variables by default. But you can do so by passing
 ``trust_env=True`` into :class:`aiohttp.ClientSession`
-constructor for extracting proxy configuration from
-*HTTP_PROXY*, *HTTPS_PROXY*, *WS_PROXY* or *WSS_PROXY* *environment
-variables* (all are case insensitive)::
+constructor.::
 
    async with aiohttp.ClientSession(trust_env=True) as session:
        async with session.get("http://python.org") as resp:
            print(resp.status)
 
+.. note::
+    aiohttp uses :func:`urllib.request.getproxies`
+    for reading the proxy configuration (e.g. from the *HTTP_PROXY* etc. environment variables) and applies them for the *HTTP*, *HTTPS*, *WS* and *WSS* schemes.
+
+    Hosts defined in ``no_proxy`` will bypass the proxy.
+
 Proxy credentials are given from ``~/.netrc`` file if present (see
 :class:`aiohttp.ClientSession` for more details).
 

docs/client_reference.rst

@@ -173,9 +173,9 @@ The client session supports the context manager protocol for self closing.
 
       .. versionadded:: 3.7
 
-   :param bool trust_env: Get proxies information from *HTTP_PROXY* /
-      *HTTPS_PROXY* environment variables if the parameter is ``True``
-      (``False`` by default).
+   :param bool trust_env: Trust environment settings for proxy configuration if the parameter
+      is ``True`` (``False`` by default). See :ref:`aiohttp-client-proxy-support` for
+      more information.
 
       Get proxy credentials from ``~/.netrc`` file if present.
 
@@ -321,8 +321,9 @@ The client session supports the context manager protocol for self closing.
 
    .. attribute:: trust_env
 
-      Should get proxies information from HTTP_PROXY / HTTPS_PROXY environment
-      variables or ~/.netrc file if present
+      Trust environment settings for proxy configuration
+      or ~/.netrc file if present. See :ref:`aiohttp-client-proxy-support` for
+      more information.
 
       :class:`bool` default is ``False``