Configuration options for media redirect

docs/usage/configuration/config_documentation.md

@@ -2182,6 +2182,39 @@ media_upload_limits:
   max_size: 500M
 ```
 ---
+### `media_redirect`
+
+*(object)* When enabled, Synapse will use HTTP redirect responses to serve media instead of directly serving the media from the media store. This can help with caching, but requires /_synapse/media/* to be routed to the media worker.
+
+This setting has the following sub-options:
+
+* `enabled` (boolean): Enables the media redirect feature. If enabled, you must specify a `media_redirect.secret` or `media_redirect.secret_path`. Defaults to `false`.
+
+* `secret` (string): Secret used to sign media redirect URLs. This must be set if `media_redirect.enabled` is set. Defaults to `null`.
+
+* `secret_path` (string): An alternative to `media_redirect.secret` that specifies a file containing the secret. Defaults to `null`.
+
+* `ttl` (duration): How long the redirect URLs should be valid for. Defaults to `"10m"`.
+
+Default configuration:
+```yaml
+media_redirect:
+  enabled: false
+```
+
+Example configurations:
+```yaml
+media_redirect:
+  enabled: true
+  secret: aiCh9gu4Zahvueveisooquu7chaiw9Ee
+```
+
+```yaml
+media_redirect:
+  enabled: true
+  secret_path: /path/to/secrets/file
+```
+---
 ### `max_image_pixels`
 
 *(byte size)* Maximum number of pixels that will be thumbnailed. Defaults to `"32M"`.