Allow loading CA certificates from memory for proxies (#3150)

Co-authored-by: Illia Volochii <illia.volochii@gmail.com>

changelog/3065.bugfix.rst

@@ -0,0 +1,3 @@
+Fixed an issue where it was not possible to pass the ca_cert_data keyword argument in a proxy context when making SSL
+requests. Previously, attempting to pass ca_cert_data in a proxy context would result in an error.
+This issue has been resolved, and users can now pass ca_cert_data when making SSL requests through a proxy context.

src/urllib3/poolmanager.py

@@ -38,6 +38,7 @@
     "cert_file",
     "cert_reqs",
     "ca_certs",
+    "ca_cert_data",
     "ssl_version",
     "ssl_minimum_version",
     "ssl_maximum_version",
@@ -73,6 +74,7 @@ class PoolKey(typing.NamedTuple):
     key_cert_file: str | None
     key_cert_reqs: str | None
     key_ca_certs: str | None
+    key_ca_cert_data: str | bytes | None
     key_ssl_version: int | str | None
     key_ssl_minimum_version: ssl.TLSVersion | None
     key_ssl_maximum_version: ssl.TLSVersion | None

test/with_dummyserver/test_proxy_poolmanager.py

@@ -78,6 +78,16 @@ def test_https_proxy(self) -> None:
             r = https.request("GET", f"{self.http_url}/")
             assert r.status == 200
 
+    def test_http_and_https_kwarg_ca_cert_data_proxy(self) -> None:
+        with open(DEFAULT_CA) as pem_file:
+            pem_file_data = pem_file.read()
+        with proxy_from_url(self.https_proxy_url, ca_cert_data=pem_file_data) as https:
+            r = https.request("GET", f"{self.https_url}/")
+            assert r.status == 200
+
+            r = https.request("GET", f"{self.http_url}/")
+            assert r.status == 200
+
     def test_https_proxy_with_proxy_ssl_context(self) -> None:
         proxy_ssl_context = create_urllib3_context()
         proxy_ssl_context.load_verify_locations(DEFAULT_CA)