scan: exclude Cylc 7 workflows from scan results

CHANGES.md

@@ -36,6 +36,9 @@ ones in. -->
 [#4777](https://github.com/cylc/cylc-flow/pull/4777) -
 Reinstate the Cylc 7 template variables for xtriggers with deprecation warnings.
 
+[#4771](https://github.com/cylc/cylc-flow/pull/4771) -
+Fix issue where Cylc 7 workflows could show in `cylc scan` output and in the UI.
+
 [#4720](https://github.com/cylc/cylc-flow/pull/4720) - Fix traceback in
 workflow logs when starting or reloading a workflow with an illegal item
 (e.g. typo) in the config.

cylc/flow/network/scan.py

@@ -83,7 +83,6 @@
 FLOW_FILES = {
     # marker files/dirs which we use to determine if something is a flow
     WorkflowFiles.Service.DIRNAME,
-    WorkflowFiles.SUITE_RC,   # cylc7 flow definition file name
     WorkflowFiles.FLOW_FILE,  # cylc8 flow definition file name
     WorkflowFiles.LOG_DIR
 }
@@ -94,20 +93,48 @@
 }
 
 
-def dir_is_flow(listing: Iterable[Path]) -> bool:
+def dir_is_flow(listing: Iterable[Path]) -> Optional[bool]:
     """Return True if a Path contains a flow at the top level.
 
     Args:
-        listing (list):
+        listing:
             A listing of the directory in question as a list of
             ``pathlib.Path`` objects.
 
     Returns:
-        bool - True if the listing indicates that this is a flow directory.
+        - True if the directory:
+          - Is a Cylc 8 workflow.
+          - Is a Cylc 7 workflow that has not yet been run.
+          - Is a Cylc 7 workflow running under Cylc 8 in compatibility mode.
+        - False if the directory:
+          - Is not a workflow.
+        - None if the directory:
+          - Is an incompatible workflow (e.g. a Cylc 7 workflow running under
+            Cylc 7).
 
     """
     names = {path.name for path in listing}
-    return bool(FLOW_FILES & names)
+
+    if WorkflowFiles.SUITE_RC in names:
+        # a Cylc 7 workflow ...
+        for path in listing:
+            if path.name == WorkflowFiles.LOG_DIR:
+                if (path / 'workflow').exists():
+                    # Cylc 8: log/workflow/log
+                    return True
+                else:
+                    # Cylc 7: log/suite/log
+                    return None
+        # workflow doesn't have a log dir so has not been run
+        # so could be either a Cylc 7 or a Cylc 8 workflow
+        return True
+
+    if FLOW_FILES & names:
+        # a pure Cylc 8 workflow
+        return True
+
+    # random directory
+    return False
 
 
 @pipe
@@ -206,13 +233,14 @@ def _scan_subdirs(listing: List[Path], depth: int) -> None:
         for task in done:
             path, depth, contents = task.result()
             running.remove(task)
-            if dir_is_flow(contents):
+            is_flow = dir_is_flow(contents)
+            if is_flow:
                 # this is a flow directory
                 yield {
                     'name': str(path.relative_to(run_dir)),
                     'path': path,
                 }
-            elif depth < max_depth:
+            elif is_flow is False and depth < max_depth:
                 # we may have a nested flow, lets see...
                 _scan_subdirs(contents, depth)
         # don't allow this to become blocking

tests/integration/test_scan.py

@@ -406,3 +406,54 @@ async def test_scan_sigstop(
             (30, f'Workflow not running: {name}')
             in [(level, msg) for _, level, msg in caplog.record_tuples]
         )
+
+
+@pytest.fixture
+def cylc7_run_dir(tmp_path):
+    """A run directory containing three Cylc 7 workflows."""
+    # a workflow that has not yet been run
+    # (could be run by either cylc 7 or 8 so should appear in scan results)
+    either = tmp_path / 'either'
+    either.mkdir()
+    (either / WorkflowFiles.SUITE_RC).touch()
+
+    # a Cylc 7 workflow that has been / is being run by Cylc 7
+    # (should not appear in scan results)
+    cylc7 = tmp_path / 'cylc7'
+    cylc7.mkdir()
+    (cylc7 / WorkflowFiles.SUITE_RC).touch()
+    Path(cylc7, WorkflowFiles.LOG_DIR, 'suite').mkdir(parents=True)
+    Path(cylc7, WorkflowFiles.LOG_DIR, 'suite', 'log').touch()
+
+    # a Cylc 7 workflow running under Cylc 8 in compatibility mode
+    # (should appear in scan results)
+    cylc8 = tmp_path / 'cylc8'
+    cylc8.mkdir()
+    (cylc8 / WorkflowFiles.SUITE_RC).touch()
+    Path(cylc8, WorkflowFiles.LOG_DIR, 'workflow').mkdir(parents=True)
+    Path(cylc8, WorkflowFiles.LOG_DIR, 'workflow', 'log').touch()
+
+    # crazy niche case of a Cylc 7 workflow that has had its DB removed
+    # and re-run under Cylc 8
+    # (should appear in scan results)
+    cylc8 = tmp_path / 'cylc78'
+    cylc8.mkdir()
+    (cylc8 / WorkflowFiles.SUITE_RC).touch()
+    Path(cylc8, WorkflowFiles.LOG_DIR, 'suite').mkdir(parents=True)
+    Path(cylc8, WorkflowFiles.LOG_DIR, 'suite', 'log').touch()
+    Path(cylc8, WorkflowFiles.LOG_DIR, 'workflow').mkdir(parents=True)
+    Path(cylc8, WorkflowFiles.LOG_DIR, 'workflow', 'log').touch()
+
+    return tmp_path
+
+
+async def test_scan_cylc7(cylc7_run_dir):
+    """It should exclude Cylc 7 workflows from scan results.
+
+    Unless they are running under Cylc 8 in Cylc 7 compatibility mode.
+    """
+    assert await listify(
+        scan(cylc7_run_dir)
+    ) == [
+        'cylc78', 'cylc8', 'either'
+    ]