Seed remote butler factory with default-disabled datastore cache manager

python/lsst/daf/butler/datastore/cache_manager.py

@@ -49,12 +49,12 @@
 from collections import defaultdict
 from collections.abc import ItemsView, Iterable, Iterator, KeysView, ValuesView
 from random import Random
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Self
 
 from lsst.resources import ResourcePath
 from pydantic import BaseModel, PrivateAttr
 
-from .._config import ConfigSubset
+from .._config import Config, ConfigSubset
 from .._config_support import processLookupConfigs
 from .._dataset_ref import DatasetId, DatasetRef
 
@@ -602,6 +602,31 @@ def cache_size(self) -> int:
     def file_count(self) -> int:
         return len(self._cache_entries)
 
+    @classmethod
+    def create_disabled(cls) -> Self:
+        """Create an instance that is disabled by default but can be
+        overridden by the environment.
+
+        Returns
+        -------
+        cache_manager : `DatastoreCacheManager`
+            A new cache manager, that is disabled by default but might be
+            enabled if environment variables are set.
+        """
+        config_str = """
+cached:
+  cacheable:
+    irrelevant: false
+  expiry:
+    mode: disabled
+    threshold: 0
+        """
+        config = Config.fromYaml(config_str)
+        return cls(
+            DatastoreCacheManagerConfig(config),
+            universe=None,  # type: ignore
+        )
+
     @classmethod
     def set_fallback_cache_directory_if_unset(cls) -> tuple[bool, str]:
         """Define a fallback cache directory if a fallback not set already.

python/lsst/daf/butler/remote_butler/_factory.py

@@ -34,6 +34,7 @@
 
 from .._butler_config import ButlerConfig
 from .._butler_instance_options import ButlerInstanceOptions
+from ..datastore.cache_manager import DatastoreCacheManager
 from ._authentication import get_authentication_token_from_environment
 from ._config import RemoteButlerConfigModel
 from ._http_connection import RemoteButlerHttpConnection
@@ -91,12 +92,15 @@ def create_butler_for_access_token(
     ) -> RemoteButler:
         if butler_options is None:
             butler_options = ButlerInstanceOptions()
+        # Use a disabled datastore cache. Environment variables can be
+        # set to override.
         return RemoteButler(
             connection=RemoteButlerHttpConnection(
                 http_client=self.http_client, server_url=self.server_url, access_token=access_token
             ),
             options=butler_options,
             cache=self._cache,
+            datastore_cache_manager=DatastoreCacheManager.create_disabled(),
         )
 
     def create_butler_with_credentials_from_environment(

python/lsst/daf/butler/remote_butler/_remote_butler.py

@@ -98,6 +98,9 @@ class RemoteButler(Butler):  # numpydoc ignore=PR02
     cache : `RemoteButlerCache`
         Cache of data shared between multiple RemoteButler instances connected
         to the same server.
+    datastore_cache_manager : `AbstractDatastoreCacheManager` or `None`
+        Datastore cache manager to use. If not provided a per-instance
+        cache manager will be constructed from default configuration.
 
     Notes
     -----
@@ -125,13 +128,14 @@ def __new__(
         connection: RemoteButlerHttpConnection,
         options: ButlerInstanceOptions,
         cache: RemoteButlerCache,
+        datastore_cache_manager: AbstractDatastoreCacheManager | None = None,
     ) -> RemoteButler:
         self = cast(RemoteButler, super().__new__(cls))
         self.storageClasses = StorageClassFactory()
 
         self._connection = connection
         self._cache = cache
-        self._datastore_cache_manager = None
+        self._datastore_cache_manager = datastore_cache_manager
 
         # Avoid a circular import by deferring this import.
         from ._registry import RemoteButlerRegistry
@@ -179,7 +183,7 @@ def dimensions(self) -> DimensionUniverse:
             return cache.dimensions
 
     @property
-    def datastore_cache_manager(self) -> AbstractDatastoreCacheManager:
+    def _cache_manager(self) -> AbstractDatastoreCacheManager:
         """Cache manager to use when reading files from the butler."""
         # RemoteButler does not get any cache configuration from the server.
         # Read the Datastore default config (which is a FileDatastore)
@@ -188,7 +192,6 @@ def datastore_cache_manager(self) -> AbstractDatastoreCacheManager:
         # defaults for DatastoreConfig no longer include the cache.
         if self._datastore_cache_manager is None:
             datastore_config = DatastoreConfig()
-            self._datastore_cache_manager: AbstractDatastoreCacheManager
             if "cached" in datastore_config:
                 self._datastore_cache_manager = DatastoreCacheManager(
                     datastore_config["cached"], universe=self.dimensions
@@ -279,7 +282,7 @@ def _get_dataset_as_python_object(
             ref,
             _to_file_payload(model),
             parameters=parameters,
-            cache_manager=self.datastore_cache_manager,
+            cache_manager=self._cache_manager,
         )
 
     def _get_file_info(