Try to catch the race condidion when creating the user with a partner (#2320)

app/account_linking.py

@@ -6,6 +6,7 @@ from typing import Optional
 import arrow
 from arrow import Arrow
 from newrelic import agent
+from psycopg2.errors import UniqueViolation
 from sqlalchemy import or_
 
 from app.db import Session
@@ -160,15 +161,55 @@ class ClientMergeStrategy(ABC):
 
 class NewUserStrategy(ClientMergeStrategy):
     def process(self) -> LinkResult:
-        # Will create a new SL User with a random password
         canonical_email = canonicalize_email(self.link_request.email)
-        new_user = User.create(
-            email=canonical_email,
-            name=self.link_request.name,
-            password=random_string(20),
-            activated=True,
-            from_partner=self.link_request.from_partner,
+        try:
+            # Will create a new SL User with a random password
+            new_user = User.create(
+                email=canonical_email,
+                name=self.link_request.name,
+                password=random_string(20),
+                activated=True,
+                from_partner=self.link_request.from_partner,
+            )
+            self.create_partner_user(new_user)
+            Session.commit()
+
+            if not new_user.created_by_partner:
+                send_welcome_email(new_user)
+
+            agent.record_custom_event(
+                "PartnerUserCreation", {"partner": self.partner.name}
+            )
+
+            return LinkResult(
+                user=new_user,
+                strategy=self.__class__.__name__,
+            )
+        except UniqueViolation:
+            return self.create_missing_link(canonical_email)
+
+    def create_missing_link(self, canonical_email: str):
+        # If there's a unique key violation due to race conditions try to create only the partner if needed
+        partner_user = PartnerUser.get_by(
+            external_user_id=self.link_request.external_user_id,
+            partner_id=self.partner.id,
         )
+        if partner_user is None:
+            # Get the user by canonical email and if not by normal email
+            user = User.get_by(email=canonical_email) or User.get_by(
+                email=self.link_request.email
+            )
+            if not user:
+                raise RuntimeError(
+                    "Tried to create only partner on UniqueViolation but cannot find the user"
+                )
+            partner_user = self.create_partner_user(user)
+            Session.commit()
+        return LinkResult(
+            user=partner_user.user, strategy=ExistingUnlinkedUserStrategy.__name__
+        )
+
+    def create_partner_user(self, new_user: User):
         partner_user = create_partner_user(
             user=new_user,
             partner_id=self.partner.id,
@@ -182,17 +223,7 @@ class NewUserStrategy(ClientMergeStrategy):
             partner_user,
             self.link_request.plan,
         )
-        Session.commit()
-
-        if not new_user.created_by_partner:
-            send_welcome_email(new_user)
-
-        agent.record_custom_event("PartnerUserCreation", {"partner": self.partner.name})
-
-        return LinkResult(
-            user=new_user,
-            strategy=self.__class__.__name__,
-        )
+        return partner_user
 
 
 class ExistingUnlinkedUserStrategy(ClientMergeStrategy):

app/alias_suffix.py

@@ -58,7 +58,7 @@ def verify_prefix_suffix(
 
     # alias_domain must be either one of user custom domains or built-in domains
     if alias_domain not in user.available_alias_domains(alias_options=alias_options):
-        LOG.e("wrong alias suffix %s, user %s", alias_suffix, user)
+        LOG.i("wrong alias suffix %s, user %s", alias_suffix, user)
         return False
 
     # SimpleLogin domain case:
@@ -75,17 +75,17 @@ def verify_prefix_suffix(
         and not config.DISABLE_ALIAS_SUFFIX
     ):
         if not alias_domain_prefix.startswith("."):
-            LOG.e("User %s submits a wrong alias suffix %s", user, alias_suffix)
+            LOG.i("User %s submits a wrong alias suffix %s", user, alias_suffix)
             return False
 
     else:
         if alias_domain not in user_custom_domains:
             if not config.DISABLE_ALIAS_SUFFIX:
-                LOG.e("wrong alias suffix %s, user %s", alias_suffix, user)
+                LOG.i("wrong alias suffix %s, user %s", alias_suffix, user)
                 return False
 
             if alias_domain not in available_sl_domains:
-                LOG.e("wrong alias suffix %s, user %s", alias_suffix, user)
+                LOG.i("wrong alias suffix %s, user %s", alias_suffix, user)
                 return False
 
     return True

tests/test_account_linking.py

@@ -144,6 +144,21 @@ def test_login_case_from_web():
     assert audit_logs[0].action == UserAuditLogAction.LinkAccount.value
 
 
+def test_new_user_strategy_create_missing_link():
+    email = random_email()
+    user = User.create(email, commit=True)
+    nus = NewUserStrategy(
+        link_request=random_link_request(
+            email=user.email, external_user_id=random_string(), from_partner=False
+        ),
+        user=None,
+        partner=get_proton_partner(),
+    )
+    result = nus.create_missing_link(user.email)
+    assert result.user.id == user.id
+    assert result.strategy == ExistingUnlinkedUserStrategy.__name__
+
+
 def test_get_strategy_existing_sl_user():
     email = random_email()
     user = User.create(email, commit=True)