From 2eb5c453ad71417bebcc45714c0c318bc956c336 Mon Sep 17 00:00:00 2001
From: Alex Gleason <alex@alexgleason.me>
Date: Sat, 23 Dec 2023 23:07:35 -0600
Subject: [PATCH] Allow configuring the origin of the service actor

---
 config/config.exs                             |  3 ++-
 .../activity_pub/activity_pub_controller.ex   | 12 +++++++++--
 .../web/activity_pub/internal_fetch_actor.ex  | 20 ++++++++++++++++---
 .../activity_pub_controller_test.exs          |  2 +-
 4 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index e1d45fd7c2..6ebfb4adcf 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -375,7 +375,8 @@
   follow_handshake_timeout: 500,
   note_replies_output_limit: 5,
   sign_object_fetches: true,
-  authorized_fetch_mode: false
+  authorized_fetch_mode: false,
+  fetch_actor_origin: nil
 
 config :pleroma, :streamer,
   workers: 3,
diff --git a/lib/pleroma/web/activity_pub/activity_pub_controller.ex b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
index ae8e939f40..9f1a723426 100644
--- a/lib/pleroma/web/activity_pub/activity_pub_controller.ex
+++ b/lib/pleroma/web/activity_pub/activity_pub_controller.ex
@@ -334,8 +334,16 @@ def relay(conn, _params) do
     |> represent_service_actor(conn)
   end
 
-  def internal_fetch(conn, _params) do
-    InternalFetchActor.get_actor()
+  def internal_fetch(%Plug.Conn{host: host} = conn, _params) do
+    with fetch_actor_origin when is_binary(fetch_actor_origin) <-
+           Pleroma.Config.get([:activitypub, :fetch_actor_origin]),
+         %URI{host: fetch_actor_host} <- URI.parse(fetch_actor_origin),
+         true <- host == fetch_actor_host do
+      fetch_actor_origin
+    else
+      _ -> Pleroma.Web.Endpoint.url()
+    end
+    |> InternalFetchActor.get_actor()
     |> represent_service_actor(conn)
   end
 
diff --git a/lib/pleroma/web/activity_pub/internal_fetch_actor.ex b/lib/pleroma/web/activity_pub/internal_fetch_actor.ex
index 0837238945..1c12859fd6 100644
--- a/lib/pleroma/web/activity_pub/internal_fetch_actor.ex
+++ b/lib/pleroma/web/activity_pub/internal_fetch_actor.ex
@@ -11,10 +11,24 @@ def init do
     # Wait for everything to settle.
     Process.sleep(1000 * 5)
     get_actor()
+    get_actor(Pleroma.Web.Endpoint.url())
   end
 
-  def get_actor do
-    "#{Pleroma.Web.Endpoint.url()}/internal/fetch"
-    |> User.get_or_create_service_actor_by_ap_id("internal.fetch")
+  def get_actor(origin) do
+    %URI{host: host} = URI.parse(origin)
+
+    nickname =
+      cond do
+        host == Pleroma.Web.Endpoint.host() -> "internal.fetch"
+        true -> "internal.fetch@#{host}"
+      end
+
+    "#{origin}/internal/fetch"
+    |> User.get_or_create_service_actor_by_ap_id(nickname)
+  end
+
+  def get_actor() do
+    (Pleroma.Config.get([:activitypub, :fetch_actor_origin]) || Pleroma.Web.Endpoint.url())
+    |> get_actor()
   end
 end
diff --git a/test/pleroma/web/activity_pub/activity_pub_controller_test.exs b/test/pleroma/web/activity_pub/activity_pub_controller_test.exs
index 0dc61c2e56..ce5e1e19c7 100644
--- a/test/pleroma/web/activity_pub/activity_pub_controller_test.exs
+++ b/test/pleroma/web/activity_pub/activity_pub_controller_test.exs
@@ -75,7 +75,7 @@ test "it returns the internal fetch user", %{conn: conn} do
         |> get(activity_pub_path(conn, :internal_fetch))
         |> json_response(200)
 
-      assert res["id"] =~ "/fetch"
+      assert res["id"] =~ "http://localhost:4001/internal/fetch"
     end
 
     test "on non-federating instance, it returns 404", %{conn: conn} do