rich media: use cachex to avoid flooding remote servers

lib/pleroma/application.ex

@@ -63,6 +63,17 @@ def start(_type, _args) do
           ],
           id: :cachex_object
         ),
+        worker(
+          Cachex,
+          [
+            :rich_media_cache,
+            [
+              default_ttl: :timer.minutes(120),
+              limit: 5000
+            ]
+          ],
+          id: :cachex_rich_media
+        ),
         worker(
           Cachex,
           [

lib/pleroma/web/rich_media/parser.ex

@@ -2,9 +2,13 @@ defmodule Pleroma.Web.RichMedia.Parser do
   @parsers [Pleroma.Web.RichMedia.Parsers.OGP]
 
   def parse(url) do
-    {:ok, %Tesla.Env{body: html}} = Pleroma.HTTP.get(url)
+    Cachex.fetch!(:rich_media_cache, url, fn _ ->
+      {:ok, %Tesla.Env{body: html}} = Pleroma.HTTP.get(url)
 
-    html |> maybe_parse() |> get_parsed_data()
+      result = html |> maybe_parse() |> get_parsed_data()
+
+      {:commit, result}
+    end)
   end
 
   defp maybe_parse(html) do