Add async interface for finalization to acme.client.ClientV2 (#9622)

* Add async interface for finalization to acme.client.ClientV2

Add `begin_order_finalization()`/`poll_finalization()` to
`acme.client.ClientV2`, which are directly analogous to
`answer_challenge()`/`poll_authorizations()`. This allows us to
finalize an order and then later poll for its completion as separate
steps.

* Address code review feedback

Rename `begin_order_finalization` -> `begin_finalization` and tweak
wording of changelog entry

acme/acme/client.py

@@ -210,23 +210,35 @@ class ClientV2:
             raise errors.ValidationError(failed)
         return orderr.update(authorizations=responses)
 
-    def finalize_order(self, orderr: messages.OrderResource, deadline: datetime.datetime,
-                       fetch_alternative_chains: bool = False) -> messages.OrderResource:
-        """Finalize an order and obtain a certificate.
+    def begin_finalization(self, orderr: messages.OrderResource
+                           ) -> messages.OrderResource:
+        """Start the process of finalizing an order.
 
         :param messages.OrderResource orderr: order to finalize
         :param datetime.datetime deadline: when to stop polling and timeout
-        :param bool fetch_alternative_chains: whether to also fetch alternative
-            certificate chains
 
-        :returns: finalized order
+        :returns: updated order
         :rtype: messages.OrderResource
-
         """
         csr = OpenSSL.crypto.load_certificate_request(
             OpenSSL.crypto.FILETYPE_PEM, orderr.csr_pem)
         wrapped_csr = messages.CertificateRequest(csr=jose.ComparableX509(csr))
-        self._post(orderr.body.finalize, wrapped_csr)
+        res = self._post(orderr.body.finalize, wrapped_csr)
+        orderr = orderr.update(body=messages.Order.from_json(res.json()))
+        return orderr
+
+    def poll_finalization(self, orderr: messages.OrderResource,
+                          deadline: datetime.datetime,
+                          fetch_alternative_chains: bool = False
+                          ) -> messages.OrderResource:
+        """
+        Poll an order that has been finalized for its status.
+        If it becomes valid, obtain the certificate.
+
+        :returns: finalized order (with certificate)
+        :rtype: messages.OrderResource
+        """
+
         while datetime.datetime.now() < deadline:
             time.sleep(1)
             response = self._post_as_get(orderr.uri)
@@ -247,6 +259,22 @@ class ClientV2:
                 return orderr
         raise errors.TimeoutError()
 
+    def finalize_order(self, orderr: messages.OrderResource, deadline: datetime.datetime,
+                       fetch_alternative_chains: bool = False) -> messages.OrderResource:
+        """Finalize an order and obtain a certificate.
+
+        :param messages.OrderResource orderr: order to finalize
+        :param datetime.datetime deadline: when to stop polling and timeout
+        :param bool fetch_alternative_chains: whether to also fetch alternative
+            certificate chains
+
+        :returns: finalized order
+        :rtype: messages.OrderResource
+
+        """
+        self.begin_finalization(orderr)
+        return self.poll_finalization(orderr, deadline, fetch_alternative_chains)
+
     def revoke(self, cert: jose.ComparableX509, rsn: int) -> None:
         """Revoke certificate.
 

certbot/CHANGELOG.md

@@ -8,6 +8,9 @@ Certbot adheres to [Semantic Versioning](https://semver.org/).
 
 * `acme.messages.OrderResource` now supports being round-tripped
   through JSON
+* acme.client.ClientV2 now provides separate `begin_finalization`
+  and `poll_finalization` methods, in addition to the existing
+  `finalize_order` method.
 
 ### Changed