Delay attachment deletion

Otherwise attachments have a high chance to disappear with akkoma-fe’s
“delete & redraft” feature when cleanup is enabled in the backend. Since
we don't know whether a deletion was intended to be part of a redraft
process or even if whether the redraft was abandoned we still have to
delete attachments eventually.
A thirty minute delay should provide sufficient time for redrafting.

Fixes: #775

config/config.exs

@@ -255,6 +255,7 @@ config :pleroma, :instance,
   external_user_synchronization: true,
   extended_nickname_format: true,
   cleanup_attachments: false,
+  cleanup_attachments_delay: 1800,
   multi_factor_authentication: [
     totp: [
       # digits 6 or 8

docs/docs/configuration/cheatsheet.md

@@ -58,6 +58,7 @@ To add configuration to your config file, you can copy it from the base config.
 * `registration_reason_length`: Maximum registration reason length (default: `500`).
 * `external_user_synchronization`: Enabling following/followers counters synchronization for external users.
 * `cleanup_attachments`: Remove attachments along with statuses. Does not affect duplicate files and attachments without status. Enabling this will increase load to database when deleting statuses on larger instances.
+* `cleanup_attachments_delay`: How many seconds to wait after post deletion before attempting to deletion; useful for “delete & redraft” functionality (default: `1800`)
 * `show_reactions`: Let favourites and emoji reactions be viewed through the API (default: `true`).
 * `password_reset_token_validity`: The time after which reset tokens aren't accepted anymore, in seconds (default: one day).
 * `local_bubble`: Array of domains representing instances closely related to yours. Used to populate the `bubble` timeline. e.g `["example.com"]`, (default: `[]`)

lib/pleroma/workers/attachments_cleanup_worker.ex

@@ -24,7 +24,11 @@ defmodule Pleroma.Workers.AttachmentsCleanupWorker do
          true <- URI.parse(actor).host == Pleroma.Web.Endpoint.host(),
          attachments <- Enum.filter(attachments, &deletable_attachment/1),
          [_ | _] <- attachments do
-      enqueue("cleanup_attachments", %{"actor" => actor, "attachments" => attachments})
+      enqueue(
+        "cleanup_attachments",
+        %{"actor" => actor, "attachments" => attachments},
+        schedule_in: Config.get!([:instance, :cleanup_attachments_delay])
+      )
     else
       _ -> {:ok, :skip}
     end

test/pleroma/workers/attachments_cleanup_worker_test.exs

@@ -8,7 +8,9 @@ defmodule Pleroma.Workers.AttachmentsCleanupWorkerTest do
 
   import Pleroma.Factory
 
+  alias Pleroma.Object
   alias Pleroma.Workers.AttachmentsCleanupWorker
+  alias Pleroma.Tests.ObanHelpers
 
   setup do
     clear_config([:instance, :cleanup_attachments], true)
@@ -78,4 +80,28 @@ defmodule Pleroma.Workers.AttachmentsCleanupWorkerTest do
 
     assert {:ok, :skip} = AttachmentsCleanupWorker.enqueue_if_needed(local_data)
   end
+
+  test "doesn't delete immediately", %{attachment: attachment, user: user} do
+    delay = 6000
+    clear_config([:instance, :cleanup_attachments_delay], delay)
+
+    note = insert(:note, %{user: user, data: %{"attachment" => [attachment.data]}})
+
+    uploads_dir = Pleroma.Config.get!([Pleroma.Uploaders.Local, :uploads])
+    %{"url" => [%{"href" => href}]} = attachment.data
+    path = "#{uploads_dir}/#{Path.basename(href)}"
+
+    assert File.exists?(path)
+
+    Object.delete(note)
+    Process.sleep(2000)
+
+    assert File.exists?(path)
+
+    ObanHelpers.perform(all_enqueued(worker: Pleroma.Workers.AttachmentsCleanupWorker))
+
+    assert Object.get_by_id(note.id).data["deleted"]
+    assert Object.get_by_id(attachment.id) == nil
+    refute File.exists?(path)
+  end
 end