MediaProxyController: Use 301 for permanent redirects

changelog.d/301-small-image-redirect.change

@@ -0,0 +1 @@
+Performance: Use 301 (permanent) redirect instead of 302 (temporary) when redirecting small images in media proxy. This allows browsers to cache the redirect response. 

lib/pleroma/web/media_proxy/media_proxy_controller.ex

@@ -71,11 +71,15 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
           drop_static_param_and_redirect(conn)
 
         content_type == "image/gif" ->
-          redirect(conn, external: media_proxy_url)
+          conn
+          |> put_status(301)
+          |> redirect(external: media_proxy_url)
 
         min_content_length_for_preview() > 0 and content_length > 0 and
             content_length < min_content_length_for_preview() ->
-          redirect(conn, external: media_proxy_url)
+          conn
+          |> put_status(301)
+          |> redirect(external: media_proxy_url)
 
         true ->
           handle_preview(content_type, conn, media_proxy_url)

test/pleroma/web/media_proxy/media_proxy_controller_test.exs

@@ -248,8 +248,8 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyControllerTest do
 
       response = get(conn, url)
 
-      assert response.status == 302
+      assert response.status == 301
-      assert redirected_to(response) == media_proxy_url
+      assert redirected_to(response, 301) == media_proxy_url
     end
 
     test "with `static` param and non-GIF image preview requested, " <>
@@ -290,8 +290,8 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyControllerTest do
 
       response = get(conn, url)
 
-      assert response.status == 302
+      assert response.status == 301
-      assert redirected_to(response) == media_proxy_url
+      assert redirected_to(response, 301) == media_proxy_url
     end
 
     test "thumbnails PNG images into PNG", %{
@@ -356,5 +356,32 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyControllerTest do
       assert response.status == 302
       assert redirected_to(response) == media_proxy_url
     end
+
+    test "redirects to media proxy URI with 301 when image is too small for preview", %{
+      conn: conn,
+      url: url,
+      media_proxy_url: media_proxy_url
+    } do
+      clear_config([:media_preview_proxy],
+        enabled: true,
+        min_content_length: 1000,
+        image_quality: 85,
+        thumbnail_max_width: 100,
+        thumbnail_max_height: 100
+      )
+
+      Tesla.Mock.mock(fn
+        %{method: :head, url: ^media_proxy_url} ->
+          %Tesla.Env{
+            status: 200,
+            body: "",
+            headers: [{"content-type", "image/png"}, {"content-length", "500"}]
+          }
+      end)
+
+      response = get(conn, url)
+      assert response.status == 301
+      assert redirected_to(response, 301) == media_proxy_url
+    end
   end
 end