🐛(backend) submit for signature handle timeout delete signing procedure

When the method `submit_for_signature` needs to delete a signing procedure
because some elements have changed overtime in the contract definition
and before the student signed the document, it appears that it may take
a while on the signature provider side to execute the deletion.
In order to handle and update our contract, we have added a try
except block to catch the timeout issue, and proceed to update the contract
as if we would have received the response from the signature provider.
Before we added the fix, the contract would keep the old reference that would
not work when the student wanted to sign the document, causing another error
because it has already been deleted after the timeout we have set in the
signature backend. In some cases, due to the timeout error, when we attempt
to delete the outdated reference, we would then have a NOT_FOUND status
code, we should also reset the contrat submission value as well to restart with
a new contrat to submit.

CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to
 
 ### Fixed
 
+- Handle timeout and exception in `submit_for_signature` to
+  update the contract without the outdated references
 - Improve signature backend `handle_notification` error catching
 - Allow to cancel an enrollment order linked to an archived course run
 
@@ -50,7 +52,6 @@ and this project adheres to
 
 - Do not update OpenEdX enrollment if this one is already
   up-to-date on the remote lms
-- 
 
 ## [2.4.0] - 2024-06-21
 

src/backend/joanie/core/exceptions.py

@@ -29,3 +29,10 @@ class CertificateGenerationError(Exception):
     Exception raised when the certificate generation process fails due to the order not meeting
     all specified conditions.
     """
+
+
+class BackendTimeout(Exception):
+    """
+    Exception raised when a backend reaches the timeout set when we are waiting
+    for the response.
+    """

src/backend/joanie/core/models/products.py

@@ -18,7 +18,7 @@
 from urllib3.util import Retry
 
 from joanie.core import enums
-from joanie.core.exceptions import CertificateGenerationError
+from joanie.core.exceptions import BackendTimeout, CertificateGenerationError
 from joanie.core.fields.schedule import OrderPaymentScheduleEncoder
 from joanie.core.flows.order import OrderFlow
 from joanie.core.models.accounts import User
@@ -38,6 +38,7 @@
 from joanie.core.utils import issuers, webhooks
 from joanie.core.utils.payment_schedule import generate as generate_payment_schedule
 from joanie.signature.backends import get_signature_backend
+from joanie.signature.exceptions import DeleteSignatureProcedureFailed
 
 logger = logging.getLogger(__name__)
 
@@ -965,9 +966,18 @@ def submit_for_signature(self, user: User):
         )
 
         if should_be_resubmitted:
-            backend_signature.delete_signing_procedure(
-                contract.signature_backend_reference
-            )
+            # The signature provider may delay confirming deletion. If timeout occurs, reset
+            # submission values, as the signature provider will delete them. In an edge case, the
+            # reference `contract.signature_backend_reference` cannot be used and may already
+            # be deleted causing a 'not found' error from the signature provider.
+            try:
+                backend_signature.delete_signing_procedure(
+                    contract.signature_backend_reference
+                )
+            except (BackendTimeout, DeleteSignatureProcedureFailed):
+                pass
+            contract.reset_submission_for_signature()
+            was_already_submitted = False
 
         # We want to submit or re-submit the contract for signature in three cases:
         # 1- the contract was never submitted for signature before

src/backend/joanie/signature/backends/lex_persona.py

@@ -9,10 +9,12 @@
 from django.core.exceptions import ValidationError
 
 import requests
+from requests.exceptions import ReadTimeout
 from rest_framework.request import Request
 from sentry_sdk import capture_exception
 
 from joanie.core import enums, models
+from joanie.core.exceptions import BackendTimeout
 from joanie.core.utils.contract import order_has_organization_owner
 from joanie.signature import exceptions
 from joanie.signature.backends.base import BaseSignatureBackend
@@ -528,7 +530,20 @@ def delete_signing_procedure(self, reference_id: str):
         url = f"{base_url}/api/workflows/{reference_id}"
         headers = {"Authorization": f"Bearer {token}"}
 
-        response = requests.delete(url, headers=headers, timeout=timeout)
+        try:
+            response = requests.delete(url, headers=headers, timeout=timeout)
+        except ReadTimeout as exception:
+            logger.error(
+                exception,
+                extra={
+                    "context": {
+                        "signature_backend_reference": reference_id,
+                    }
+                },
+            )
+            raise BackendTimeout(
+                f"Deletion request is taking longer than expected for reference: {reference_id}"
+            ) from exception
 
         if not response.ok:
             logger.error(