Merge pull request #5670 from smarie/pr_proxy_conf_helper_and_doc

Proxy related doc updates

AUTHORS.rst

@@ -190,3 +190,4 @@ Patches and Suggestions
 - Antti Kaihola (`@akaihola <https://github.com/akaihola>`_)
 - "Dull Bananas" <dull.bananas0@gmail.com> (`@dullbananas <https://github.com/dullbananas>`_)
 - Alessio Izzo (`@aless10 <https://github.com/aless10>`_)
+- Sylvain Marié (`@smarie <https://github.com/smarie>`_)

docs/user/advanced.rst

@@ -589,10 +589,26 @@ If you need to use a proxy, you can configure individual requests with the
 
     requests.get('http://example.org', proxies=proxies)
 
-You can also configure proxies by setting the environment variables
-``HTTP_PROXY`` and ``HTTPS_PROXY``.
+Alternatively you can configure it once for an entire
+:class:`Session <requests.Session>`::
 
-::
+    import requests
+
+    proxies = {
+      'http': 'http://10.10.1.10:3128',
+      'https': 'http://10.10.1.10:1080',
+    }
+    session = request.Session()
+    session.proxies.update(proxies)
+
+    session.get('http://example.org')
+
+When the proxies configuration is not overridden in python as shown above,
+by default Requests relies on the proxy configuration defined by standard
+environment variables ``http_proxy``, ``https_proxy``, ``no_proxy`` and
+``curl_ca_bundle``. Uppercase variants of these variables are also supported.
+You can therefore set them to configure Requests (only set the ones relevant
+to your needs)::
 
     $ export HTTP_PROXY="http://10.10.1.10:3128"
     $ export HTTPS_PROXY="http://10.10.1.10:1080"
@@ -601,9 +617,17 @@ You can also configure proxies by setting the environment variables
     >>> import requests
     >>> requests.get('http://example.org')
 
-To use HTTP Basic Auth with your proxy, use the `http://user:password@host/` syntax::
+To use HTTP Basic Auth with your proxy, use the `http://user:password@host/`
+syntax in any of the above configuration entries::
 
-    proxies = {'http': 'http://user:pass@10.10.1.10:3128/'}
+    $ export HTTPS_PROXY="http://user:pass@10.10.1.10:1080"
+
+    $ python
+    >>> proxies = {'http': 'http://user:pass@10.10.1.10:3128/'}
+
+.. warning:: Storing sensitive username and password information in an
+   environment variable or a version-controled file is a security risk and is
+   highly discouraged.
 
 To give a proxy for a specific scheme and host, use the
 `scheme://hostname` form for the key.  This will match for
@@ -615,6 +639,23 @@ any request to the given scheme and exact hostname.
 
 Note that proxy URLs must include the scheme.
 
+Finally, note that using a proxy for https connections typically requires your
+local machine to trust the proxy's root certificate. By default the list of
+certificates trusted by Requests can be found with::
+
+    from requests.utils import DEFAULT_CA_BUNDLE_PATH
+    print(DEFAULT_CA_BUNDLE_PATH)
+
+You override this default certificate bundle by setting the standard
+``curl_ca_bundle`` environment variable to another file path::
+
+    $ export curl_ca_bundle="/usr/local/myproxy_info/cacert.pem"
+    $ export https_proxy="http://10.10.1.10:1080"
+
+    $ python
+    >>> import requests
+    >>> requests.get('https://example.org')
+
 SOCKS
 ^^^^^