Fix multinode cloud component (#15965)

* fix multinode cloud component
* add tests

(cherry picked from commit d21b899)

src/lightning_app/CHANGELOG.md

@@ -54,6 +54,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed multiprocessing breakpoint ([#15950](https://github.com/Lightning-AI/lightning/pull/15950))
 - Fixed detection of a Lightning App running in debug mode ([#15951](https://github.com/Lightning-AI/lightning/pull/15951))
 - Fixed `ImportError` on Multinode if package not present ([#15963](https://github.com/Lightning-AI/lightning/pull/15963))
+- Fixed MultiNode Component to use separate cloud computes ([#15965](https://github.com/Lightning-AI/lightning/pull/15965))
+
 
 ## [1.8.3] - 2022-11-22
 

src/lightning_app/components/multi_node/base.py

@@ -66,7 +66,7 @@ def run(
             *[
                 work_cls(
                     *work_args,
-                    cloud_compute=cloud_compute,
+                    cloud_compute=cloud_compute.clone(),
                     **work_kwargs,
                     parallel=True,
                 )

src/lightning_app/utilities/packaging/cloud_compute.py

@@ -82,7 +82,7 @@ def __post_init__(self) -> None:
 
         # All `default` CloudCompute are identified in the same way.
         if self._internal_id is None:
-            self._internal_id = "default" if self.name == "default" else uuid4().hex[:7]
+            self._internal_id = self._generate_id()
 
         # Internal arguments for now.
         self.preemptible = False
@@ -118,6 +118,14 @@ def id(self) -> Optional[str]:
     def is_default(self) -> bool:
         return self.name == "default"
 
+    def _generate_id(self):
+        return "default" if self.name == "default" else uuid4().hex[:7]
+
+    def clone(self):
+        new_dict = self.to_dict()
+        new_dict["_internal_id"] = self._generate_id()
+        return self.from_dict(new_dict)
+
 
 def _verify_mount_root_dirs_are_unique(mounts: Union[None, Mount, List[Mount], Tuple[Mount]]) -> None:
     if isinstance(mounts, (list, tuple, set)):

tests/tests_app/components/multi_node/test_base.py

@@ -1,4 +1,5 @@
 from re import escape
+from unittest import mock
 
 import pytest
 from tests_app.helpers.utils import no_warning_call
@@ -17,3 +18,14 @@ def run(self):
 
     with no_warning_call(UserWarning, match=escape("You set MultiNode(num_nodes=1, ...)` but ")):
         MultiNode(Work, num_nodes=1, cloud_compute=CloudCompute("gpu"))
+
+
+@mock.patch("lightning_app.components.multi_node.base.is_running_in_cloud", mock.Mock(return_value=True))
+def test_multi_node_separate_cloud_computes():
+    class Work(LightningWork):
+        def run(self):
+            pass
+
+    m = MultiNode(Work, num_nodes=2, cloud_compute=CloudCompute("gpu"))
+
+    assert len({w.cloud_compute._internal_id for w in m.ws}) == len(m.ws)

tests/tests_app/utilities/packaging/test_cloud_compute.py

@@ -41,3 +41,21 @@ def test_cloud_compute_with_non_unique_mount_root_dirs():
 
     with pytest.raises(ValueError, match="Every Mount attached to a work must have a unique"):
         CloudCompute("gpu", mounts=[mount_1, mount_2])
+
+
+def test_cloud_compute_clone():
+    c1 = CloudCompute("gpu")
+    c2 = c1.clone()
+
+    assert isinstance(c2, CloudCompute)
+
+    c1_dict = c1.to_dict()
+    c2_dict = c2.to_dict()
+
+    assert len(c1_dict) == len(c2_dict)
+
+    for k in c1_dict.keys():
+        if k == "_internal_id":
+            assert c1_dict[k] != c2_dict[k]
+        else:
+            assert c1_dict[k] == c2_dict[k]