Implement synapse issue #16751: Treat local_media_directory as optional storage provider

changelog.d/19204.feature

@@ -0,0 +1 @@
+Made the local media directory optional by treating it as a storage provider. This allows off-site media storage without local cache, where media is stored directly to remote providers only, with temporary files used for thumbnail generation when needed. Contributed by Patrice Brend'amour @dr.allgood.

docs/usage/configuration/config_documentation.md

@@ -2092,6 +2092,15 @@ Example configuration:
 enable_media_repo: false
 ```
 ---
+### `enable_local_media_storage`
+
+*(boolean)* Enable the local on-disk media storage provider. When disabled, media is stored only in configured media_storage_providers and temporary files are used for processing. Defaults to `true`.
+
+Example configuration:
+```yaml
+enable_local_media_storage: false
+```
+---
 ### `media_store_path`
 
 *(string)* Directory where uploaded images and attachments are stored. Defaults to `"media_store"`.

schema/synapse-config.schema.yaml

@@ -2338,6 +2338,15 @@ properties:
     default: true
     examples:
       - false
+  enable_local_media_storage:
+    type: boolean
+    description: >-
+      Enable the local on-disk media storage provider. When disabled, media is
+      stored only in configured media_storage_providers and temporary files are
+      used for processing.
+    default: true
+    examples:
+      - false
   media_store_path:
     type: string
     description: Directory where uploaded images and attachments are stored.

synapse/config/repository.py

@@ -174,6 +174,11 @@ def read_config(self, config: JsonDict, **kwargs: Any) -> None:
             config.get("media_store_path", "media_store")
         )
 
+        # Whether to enable the local media storage provider. When disabled,
+        # media will only be stored in configured storage providers and temp
+        # files will be used for processing.
+        self.enable_local_media_storage = config.get("enable_local_media_storage", True)
+
         backup_media_store_path = config.get("backup_media_store_path")
 
         synchronous_backup_media_store = config.get(