fix: use notebooks config fallback for culling (#1108)

Author: olevski

components/renku_data_services/notebooks/core_sessions.py

@@ -527,24 +527,36 @@ def get_culling(
     user: AuthenticatedAPIUser | AnonymousAPIUser, resource_pool: ResourcePool, nb_config: NotebooksConfig
 ) -> Culling:
     """Create the culling specification for an AmaltheaSession."""
-    if user.is_anonymous:
-        # NOTE: Anonymous sessions should not be hibernated at all, but there is no such option in Amalthea
-        # So in this case we set a very low hibernation threshold so the session is deleted quickly after
-        # it is hibernated.
-        hibernation_threshold: timedelta | None = timedelta(seconds=1)
-    else:
-        hibernation_threshold = (
-            timedelta(seconds=resource_pool.hibernation_threshold)
-            if resource_pool.hibernation_threshold is not None
-            else None
-        )
+    hibernation_threshold: timedelta | None = None
+    # NOTE: A value of zero on the resource_pool hibernation threshold
+    # is interpreted by Amalthea as "never automatically delete after hibernation"
+    match (user.is_anonymous, resource_pool.hibernation_threshold):
+        case True, _:
+            # NOTE: Anonymous sessions should not be hibernated at all, but there is no such option in Amalthea
+            # So in this case we set a very low hibernation threshold so the session is deleted quickly after
+            # it is hibernated.
+            hibernation_threshold = timedelta(seconds=1)
+        case False, int():
+            hibernation_threshold = timedelta(seconds=resource_pool.hibernation_threshold)
+        case False, None:
+            hibernation_threshold = timedelta(seconds=nb_config.sessions.culling.registered.hibernated_seconds)
+
+    idle_duration: timedelta | None = None
+    # NOTE: A value of zero on the resource_pool idle threshold
+    # is interpreted by Amalthea as "never automatically hibernate for idleness"
+    match (user.is_anonymous, resource_pool.idle_threshold):
+        case True, None:
+            idle_duration = timedelta(seconds=nb_config.sessions.culling.anonymous.idle_seconds)
+        case _, int():
+            idle_duration = timedelta(seconds=resource_pool.idle_threshold)
+        case False, None:
+            idle_duration = timedelta(seconds=nb_config.sessions.culling.registered.idle_seconds)
+
     return Culling(
         maxAge=timedelta(seconds=nb_config.sessions.culling.registered.max_age_seconds),
         maxFailedDuration=timedelta(seconds=nb_config.sessions.culling.registered.failed_seconds),
         maxHibernatedDuration=hibernation_threshold,
-        maxIdleDuration=timedelta(seconds=resource_pool.idle_threshold)
-        if resource_pool.idle_threshold is not None
-        else None,
+        maxIdleDuration=idle_duration,
         maxStartingDuration=timedelta(seconds=nb_config.sessions.culling.registered.pending_seconds),
     )
 

components/renku_data_services/notebooks/crs.py

@@ -184,7 +184,12 @@ def __deserialize_duration(cls, val: Any, handler: Any) -> Any:
 
 
 class Culling(_ASCulling, CullingDurationParsingMixin):
-    """Amalthea session culling configuration."""
+    """Amalthea session culling configuration.
+
+    A value of zero for any of the values indicates that the automatic action will never happen.
+    I.e. a value of zero for `maxIdleDuration` indicates that the session will never be hibernated
+    no matter how long it is idle.
+    """
 
     pass