Added the ability to upload background, logo, default user avatar, instance thumbnail, and the NSFW hiding image via AdminFE

lib/pleroma/web/mastodon_api/views/instance_view.ex

@@ -23,7 +23,7 @@ defmodule Pleroma.Web.MastodonAPI.InstanceView do
         streaming_api: Pleroma.Web.Endpoint.websocket_url()
       },
       stats: Pleroma.Stats.get_stats(),
-      thumbnail: Pleroma.Web.base_url() <> "/instance/thumbnail.jpeg",
+      thumbnail: instance_thumbnail(),
       languages: ["en"],
       registrations: Keyword.get(instance, :registrations_open),
       # Extra (not present in Mastodon):
@@ -87,4 +87,9 @@ defmodule Pleroma.Web.MastodonAPI.InstanceView do
     end
     |> Map.put(:enabled, Config.get([:instance, :federating]))
   end
+
+  defp instance_thumbnail do
+    Pleroma.Config.get([:instance, :instance_thumbnail]) ||
+      "#{Pleroma.Web.base_url()}/instance/thumbnail.jpeg"
+  end
 end