scheduler: add 'none' scheduler_type to skip PodGroup creation

src/ui/openapi.json

@@ -8759,7 +8759,8 @@
       "BackendSchedulerType": {
         "type": "string",
         "enum": [
-          "kai"
+          "kai",
+          "none"
         ],
         "title": "BackendSchedulerType",
         "description": "Defines the type of scheduler used by the backend "

src/ui/src/lib/api/generated.ts

@@ -105,6 +105,7 @@ export type BackendSchedulerType = typeof BackendSchedulerType[keyof typeof Back
 
 export const BackendSchedulerType = {
   kai: 'kai',
+  none: 'none',
 } as const;
 
 /**

src/ui/src/mocks/generated-mocks.ts

@@ -88,6 +88,7 @@ export type BackendSchedulerType = (typeof BackendSchedulerType)[keyof typeof Ba
 
 export const BackendSchedulerType = {
   kai: "kai",
+  none: "none",
 } as const;
 
 /**

src/utils/connectors/postgres.py

@@ -2478,6 +2478,11 @@ def list_from_db(cls, backends: List[str] | None = None,
 class BackendSchedulerType(enum.Enum):
     """ Defines the type of scheduler used by the backend """
     KAI = 'kai'
+    # No gang-scheduler integration — pods are scheduled by `scheduler_name`
+    # (typically the K8s default scheduler). Skips PodGroup CR creation, which
+    # removes the kai-scheduler dependency for workflows that don't need
+    # gang scheduling. See NVIDIA/OSMO#936.
+    NONE = 'none'
 
 
 class BackendSchedulerSettings(pydantic.BaseModel):

src/utils/job/kb_objects.py

@@ -608,8 +608,12 @@ def get_k8s_object_factory(backend: connectors.Backend) -> K8sObjectFactory:
     scheduler_type = scheduler_settings.scheduler_type
     if scheduler_type == connectors.BackendSchedulerType.KAI:
         return KaiK8sObjectFactory(backend)
-    else:
-        raise osmo_errors.OSMOServerError(f'Unsupported scheduler type: {scheduler_type}')
+    if scheduler_type == connectors.BackendSchedulerType.NONE:
+        # Base K8sObjectFactory does exactly what 'none' needs: no PodGroup CR,
+        # `scheduler_name` written to pod.spec.schedulerName, no scheduler
+        # CRDs (queues/topologies), no priority/topology features. See #936.
+        return K8sObjectFactory(scheduler_settings.scheduler_name)
+    raise osmo_errors.OSMOServerError(f'Unsupported scheduler type: {scheduler_type}')
 
 
 class FileMount(pydantic.BaseModel):