tree: resolve deep remote:// urls (#4568)

Fixes #4556

dvc/tree/__init__.py

@@ -43,10 +43,10 @@ def _get_conf(repo, **kwargs):
         remote_conf = repo.config["remote"][name.lower()]
     else:
         remote_conf = kwargs
-    return _resolve_remote_refs(repo.config, remote_conf)
+    return _resolve_remote_refs(repo, remote_conf)
 
 
-def _resolve_remote_refs(config, remote_conf):
+def _resolve_remote_refs(repo, remote_conf):
     # Support for cross referenced remotes.
     # This will merge the settings, shadowing base ref with remote_conf.
     # For example, having:
@@ -72,7 +72,7 @@ def _resolve_remote_refs(config, remote_conf):
     if parsed.scheme != "remote":
         return remote_conf
 
-    base = config["remote"][parsed.netloc]
+    base = _get_conf(repo, name=parsed.netloc)
     url = posixpath.join(base["url"], parsed.path.lstrip("/"))
     return {**base, **remote_conf, "url": url}
 

tests/unit/tree/test_tree.py

@@ -0,0 +1,18 @@
+from dvc.path_info import CloudURLInfo
+from dvc.tree import get_cloud_tree
+
+
+def test_get_cloud_tree(tmp_dir, dvc):
+    tmp_dir.add_remote(name="base", url="s3://bucket/path", default=False)
+    tmp_dir.add_remote(name="first", url="remote://base/first", default=False)
+    tmp_dir.add_remote(
+        name="second", url="remote://first/second", default=False
+    )
+
+    base = CloudURLInfo("s3://bucket/path")
+    first = base / "first"
+    second = first / "second"
+
+    assert get_cloud_tree(dvc, name="base").path_info == base
+    assert get_cloud_tree(dvc, name="first").path_info == first
+    assert get_cloud_tree(dvc, name="second").path_info == second