Make alias symlinks relative

src/simdb/remote/core/alias.py

@@ -1,3 +1,4 @@
+import os
 from pathlib import Path
 
 from simdb.remote.core.typing import current_app
@@ -15,4 +16,7 @@ def create_alias_dir(simulation):
         if len(alias_subpath.parts) > 1:
             alias_path.parent.mkdir(parents=True, exist_ok=True)
 
-        alias_path.symlink_to(base_dir / simulation.uuid.hex)
+        relative_target = os.path.relpath(
+            base_dir / simulation.uuid.hex, start=alias_path.parent
+        )
+        alias_path.symlink_to(relative_target, target_is_directory=True)

tests/remote/test_alias.py

@@ -0,0 +1,34 @@
+from pathlib import Path
+from types import SimpleNamespace
+from uuid import uuid4
+
+from simdb.remote.core import alias
+
+
+def test_nested_alias_uses_relative_symlink_that_survives_move(tmp_path, monkeypatch):
+    base_dir = tmp_path / "storage"
+    base_dir.mkdir()
+
+    simulation = SimpleNamespace(alias="user/project/case", uuid=uuid4())
+    simulation_dir = base_dir / simulation.uuid.hex
+    simulation_dir.mkdir()
+    config = SimpleNamespace(
+        get_string_option=lambda option: str(base_dir),
+    )
+    monkeypatch.setattr(
+        alias,
+        "current_app",
+        SimpleNamespace(simdb_config=config),
+    )
+
+    alias.create_alias_dir(simulation)
+
+    alias_path = base_dir / "aliases" / simulation.alias
+    assert alias_path.readlink() == Path("../../..") / simulation.uuid.hex
+    assert alias_path.resolve() == simulation_dir
+
+    moved_base_dir = tmp_path / "moved-storage"
+    base_dir.rename(moved_base_dir)
+
+    moved_alias_path = moved_base_dir / "aliases" / simulation.alias
+    assert moved_alias_path.resolve() == moved_base_dir / simulation.uuid.hex