feat: list all registered schedulers (#1009)

Author: azzhipa

torchx/schedulers/__init__.py

@@ -13,7 +13,7 @@
 from torchx.schedulers.api import Scheduler
 from torchx.util.entrypoints import load_group
 
-DEFAULT_SCHEDULER_MODULES: Mapping[str, str] = {
+BUILTIN_SCHEDULER_MODULES: Mapping[str, str] = {
     "local_docker": "torchx.schedulers.docker_scheduler",
     "local_cwd": "torchx.schedulers.local_scheduler",
     "slurm": "torchx.schedulers.slurm_scheduler",
@@ -39,24 +39,25 @@ def run(*args: object, **kwargs: object) -> Scheduler:
     return run
 
 
+def default_schedulers() -> dict[str, SchedulerFactory]:
+    """Build default schedulers (built-in + extras from torchx.schedulers.extra)."""
+    return {
+        **{s: _defer_load_scheduler(p) for s, p in BUILTIN_SCHEDULER_MODULES.items()},
+        **load_group("torchx.schedulers.extra", default={}),
+    }
+
+
 def get_scheduler_factories(
-    group: str = "torchx.schedulers", skip_defaults: bool = False
+    group: str = "torchx.schedulers",
+    skip_defaults: bool = False,
 ) -> dict[str, SchedulerFactory]:
     """
     get_scheduler_factories returns all the available schedulers names under `group` and the
     method to instantiate them.
 
     The first scheduler in the dictionary is used as the default scheduler.
     """
-
-    if skip_defaults:
-        default_schedulers = {}
-    else:
-        default_schedulers: dict[str, SchedulerFactory] = {}
-        for scheduler, path in DEFAULT_SCHEDULER_MODULES.items():
-            default_schedulers[scheduler] = _defer_load_scheduler(path)
-
-    return load_group(group, default=default_schedulers)
+    return load_group(group, default={} if skip_defaults else default_schedulers())
 
 
 def get_default_scheduler_name() -> str:

torchx/schedulers/test/registry_test.py

@@ -43,3 +43,75 @@ def test_get_local_schedulers(self, mock_load_group: MagicMock) -> None:
 
         for scheduler in schedulers.values():
             self.assertEqual("test_session", scheduler.session_name)
+
+    @patch("torchx.schedulers.load_group")
+    def test_torchx_schedulers_overrides_all(self, mock_load_group: MagicMock) -> None:
+        """torchx.schedulers completely overrides defaults and ignores extras"""
+        mock_custom: MagicMock = MagicMock()
+        mock_extra: MagicMock = MagicMock()
+
+        mock_load_group.side_effect = lambda group, default: (
+            {"custom": mock_custom}
+            if group == "torchx.schedulers"
+            else {"extra": mock_extra} if group == "torchx.schedulers.extra" else {}
+        )
+
+        factories = get_scheduler_factories()
+
+        self.assertEqual(factories, {"custom": mock_custom})
+        self.assertNotIn("local_docker", factories)
+        self.assertNotIn("extra", factories)
+
+    @patch("torchx.schedulers.load_group")
+    def test_no_custom_returns_defaults_and_extras(
+        self, mock_load_group: MagicMock
+    ) -> None:
+        """no custom schedulers returns built-in + extras"""
+        mock_extra: MagicMock = MagicMock()
+
+        mock_load_group.side_effect = lambda group, default: (
+            {"extra": mock_extra} if group == "torchx.schedulers.extra" else default
+        )
+
+        factories = get_scheduler_factories()
+
+        self.assertIn("local_docker", factories)
+        self.assertIn("slurm", factories)
+        self.assertIn("extra", factories)
+
+    @patch("torchx.schedulers.load_group")
+    def test_no_custom_no_extras_returns_builtins(
+        self, mock_load_group: MagicMock
+    ) -> None:
+        """no custom, no extras returns only built-in schedulers"""
+        mock_load_group.side_effect = lambda group, default: default
+
+        factories = get_scheduler_factories()
+
+        self.assertIn("local_docker", factories)
+        self.assertIn("slurm", factories)
+
+    @patch("torchx.schedulers.load_group")
+    def test_skip_defaults_returns_empty(self, mock_load_group: MagicMock) -> None:
+        """skip_defaults=True with no custom schedulers returns empty"""
+        mock_load_group.side_effect = lambda group, default: default
+
+        factories = get_scheduler_factories(skip_defaults=True)
+
+        self.assertEqual(factories, {})
+
+    @patch("torchx.schedulers.load_group")
+    def test_custom_scheduler_is_default(self, mock_load_group: MagicMock) -> None:
+        """first custom scheduler becomes the default"""
+        mock_aws: MagicMock = MagicMock()
+        mock_custom: MagicMock = MagicMock()
+
+        mock_load_group.side_effect = lambda group, default: (
+            {"aws_batch": mock_aws, "custom_1": mock_custom}
+            if group == "torchx.schedulers"
+            else {}
+        )
+
+        default_name = get_default_scheduler_name()
+
+        self.assertIn(default_name, ["aws_batch", "custom_1"])