Fixed #26029 -- Allowed configuring custom file storage backends.

django/conf/global_settings.py

@@ -280,6 +280,8 @@ SECRET_KEY_FALLBACKS = []
 # Default file storage mechanism that holds media.
 DEFAULT_FILE_STORAGE = "django.core.files.storage.FileSystemStorage"
 
+STORAGES = {}
+
 # Absolute filesystem path to the directory that will hold user-uploaded files.
 # Example: "/var/www/example.com/media/"
 MEDIA_ROOT = ""

django/core/files/storage/__init__.py

@@ -4,6 +4,7 @@ from django.utils.module_loading import import_string
 
 from .base import Storage
 from .filesystem import FileSystemStorage
+from .handler import InvalidStorageError, StorageHandler
 from .memory import InMemoryStorage
 
 __all__ = (
@@ -13,6 +14,9 @@ __all__ = (
     "DefaultStorage",
     "default_storage",
     "get_storage_class",
+    "InvalidStorageError",
+    "StorageHandler",
+    "storages",
 )
 
 
@@ -25,4 +29,5 @@ class DefaultStorage(LazyObject):
         self._wrapped = get_storage_class()()
 
 
+storages = StorageHandler()
 default_storage = DefaultStorage()

django/core/files/storage/handler.py

@@ -0,0 +1,46 @@
+from django.conf import settings
+from django.core.exceptions import ImproperlyConfigured
+from django.utils.functional import cached_property
+from django.utils.module_loading import import_string
+
+
+class InvalidStorageError(ImproperlyConfigured):
+    pass
+
+
+class StorageHandler:
+    def __init__(self, backends=None):
+        # backends is an optional dict of storage backend definitions
+        # (structured like settings.STORAGES).
+        self._backends = backends
+        self._storages = {}
+
+    @cached_property
+    def backends(self):
+        if self._backends is None:
+            self._backends = settings.STORAGES.copy()
+        return self._backends
+
+    def __getitem__(self, alias):
+        try:
+            return self._storages[alias]
+        except KeyError:
+            try:
+                params = self.backends[alias]
+            except KeyError:
+                raise InvalidStorageError(
+                    f"Could not find config for '{alias}' in settings.STORAGES."
+                )
+            storage = self.create_storage(params)
+            self._storages[alias] = storage
+            return storage
+
+    def create_storage(self, params):
+        params = params.copy()
+        backend = params.pop("BACKEND")
+        options = params.pop("OPTIONS", {})
+        try:
+            storage_cls = import_string(backend)
+        except ImportError as e:
+            raise InvalidStorageError(f"Could not find backend {backend!r}: {e}") from e
+        return storage_cls(**options)

django/test/signals.py

@@ -111,6 +111,23 @@ def reset_template_engines(*, setting, **kwargs):
         get_default_renderer.cache_clear()
 
 
+@receiver(setting_changed)
+def storages_changed(*, setting, **kwargs):
+    from django.core.files.storage import storages
+
+    if setting in (
+        "STORAGES",
+        "STATIC_ROOT",
+        "STATIC_URL",
+    ):
+        try:
+            del storages.backends
+        except AttributeError:
+            pass
+        storages._backends = None
+        storages._storages = {}
+
+
 @receiver(setting_changed)
 def clear_serializers_cache(*, setting, **kwargs):
     if setting == "SERIALIZATION_MODULES":