WIP: reworking along TJ's lines

python/lsst/pipe/base/executionButlerBuilder.py

@@ -228,8 +228,30 @@ def _export(
 
 
 def _setupNewButler(
-    butler: Butler, outputLocation: ResourcePath, dirExists: bool, transfer: bool = False
+    butler: Butler,
+    outputLocation: ResourcePath,
+    dirExists: bool,
+    datastoreRoot: Optional[str] = None,
 ) -> Butler:
+    """Set up the execution butler
+
+    Parameters
+    ----------
+    butler : `Butler`
+        The original butler, upon which the execution butler is based.
+    outputLocation : `ResourcePath`
+        Location of the execution butler.
+    dirExists : `bool`
+        Does the ``outputLocation`` exist, and if so, should it be clobbered?
+    datastoreRoot : `str`, optional
+        Path for the execution butler datastore. If not specified, then the
+        original butler's datastore will be used.
+
+    Returns
+    -------
+    execution_butler : `Butler`
+        Execution butler.
+    """
     # Set up the new butler object at the specified location
     if dirExists:
         # Remove the existing table, if the code got this far and this exists
@@ -254,9 +276,10 @@ def _setupNewButler(
 
     # record the current root of the datastore if it is specified relative
     # to the butler root
-    butlerDir = butler._config.configDir
-    if config.get(("datastore", "root")) == BUTLER_ROOT_TAG and butlerDir is not None:
-        config["datastore", "root"] = (outputLocation if transfer else butlerDir).geturl()
+    if datastoreRoot is not None:
+        config["datastore", "root"] = datastoreRoot
+    elif config.get(("datastore", "root")) == BUTLER_ROOT_TAG and butler._config.configDir is not None:
+        config["datastore", "root"] = butler._config.configDir.geturl()
     config["datastore", "trust_get_request"] = True
 
     # Requires that we use the dimension configuration from the original
@@ -328,7 +351,8 @@ def buildExecutionButler(
     clobber: bool = False,
     butlerModifier: Optional[Callable[[Butler], Butler]] = None,
     collections: Optional[Iterable[str]] = None,
-    transfer: str = "none",
+    datastore_root: Optional[str] = None,
+    transfer: str = "auto",
 ) -> Butler:
     r"""buildExecutionButler is a function that is responsible for exporting
     input `QuantumGraphs` into a new minimal `~lsst.daf.butler.Butler` which
@@ -372,11 +396,13 @@ def buildExecutionButler(
         `~lsst.daf.butler.Butler` when creating the execution butler. If not
         supplied the `~lsst.daf.butler.Butler`\ 's `~lsst.daf.butler.Registry`
         default collections will be used.
+    datastore_root : `str`, Optional
+        Root directory for datastore of execution butler. If `None`, then the
+        original butler's datastore will be used.
     transfer : `str`
         How (and whether) the input datasets should be added to the execution
-        butler datastore. If `"none"`, no transfer will be made, and the
-        original datastore utilised. Otherwise, this should be a ``transfer``
-        string recognized by :func:`lsst.resources.ResourcePath.transfer_from`.
+        butler datastore. This should be a ``transfer`` string recognized by
+        :func:`lsst.resources.ResourcePath.transfer_from`.
 
     Returns
     -------
@@ -410,15 +436,15 @@ def buildExecutionButler(
     exports, inserts = _accumulate(graph, dataset_types)
     yamlBuffer = _export(butler, collections, exports, inserts)
 
-    newButler = _setupNewButler(butler, outputLocation, dirExists)
+    newButler = _setupNewButler(butler, outputLocation, dirExists, datastore_root)
 
     newButler = _import(yamlBuffer, newButler, inserts, run, butlerModifier)
 
     # Transfer the existing datasets directly from the source butler.
     newButler.transfer_from(
         butler,
         exports,
-        transfer="auto" if transfer == "none" else transfer,
+        transfer=transfer,
         skip_missing=False,  # Everything should exist.
         register_dataset_types=True,
     )