[#2497] Added video preview proxy. Switched from exexec to Port.

lib/pleroma/exec.ex

@@ -1,38 +0,0 @@
-# Pleroma: A lightweight social networking server
-# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
-# SPDX-License-Identifier: AGPL-3.0-only
-
-defmodule Pleroma.Exec do
-  @moduledoc "Pleroma wrapper around Exexec commands."
-
-  alias Pleroma.Config
-
-  def ensure_started(options_overrides \\ %{}) do
-    options =
-      if Config.get([:exexec, :root_mode]) || System.get_env("USER") == "root" do
-        # Note: running as `root` is discouraged (yet Gitlab CI does that by default)
-        %{root: true, user: "root", limit_users: ["root"]}
-      else
-        %{}
-      end
-
-    options =
-      options
-      |> Map.merge(Config.get([:exexec, :options], %{}))
-      |> Map.merge(options_overrides)
-
-    with {:error, {:already_started, pid}} <- Exexec.start(options) do
-      {:ok, pid}
-    end
-  end
-
-  def run(cmd, options \\ %{}) do
-    ensure_started()
-    Exexec.run(cmd, options)
-  end
-
-  def cmd(cmd, options \\ %{}) do
-    options = Map.merge(%{sync: true, stdout: true}, options)
-    run(cmd, options)
-  end
-end

lib/pleroma/helpers/media_helper.ex

@@ -7,19 +7,24 @@ defmodule Pleroma.Helpers.MediaHelper do
   Handles common media-related operations.
   """
 
-  def ffmpeg_resize_remote(uri, %{max_width: max_width, max_height: max_height}) do
+  def ffmpeg_resize(uri_or_path, %{max_width: max_width, max_height: max_height}) do
     cmd = ~s"""
-    curl -L "#{uri}" |
-    ffmpeg -i pipe:0 -f lavfi -i color=c=white \
+    ffmpeg -i #{uri_or_path} -f lavfi -i color=c=white \
       -filter_complex "[0:v] scale='min(#{max_width},iw)':'min(#{max_height},ih)': \
         force_original_aspect_ratio=decrease [scaled]; \
         [1][scaled] scale2ref [bg][img]; [bg] setsar=1 [bg]; [bg][img] overlay=shortest=1" \
-      -f image2 -vcodec mjpeg -frames:v 1 pipe:1 | \
-    cat
+      -loglevel quiet -f image2 -vcodec mjpeg -frames:v 1 pipe:1
     """
 
-    with {:ok, [stdout: stdout_list]} <- Pleroma.Exec.cmd(cmd) do
-      {:ok, Enum.join(stdout_list)}
+    pid = Port.open({:spawn, cmd}, [:use_stdio, :in, :stream, :exit_status, :binary])
+
+    receive do
+      {^pid, {:data, data}} ->
+        send(pid, {self(), :close})
+        {:ok, data}
+
+      {^pid, {:exit_status, status}} when status > 0 ->
+        {:error, status}
     end
   end
 end

lib/pleroma/web/media_proxy/media_proxy_controller.ex

@@ -66,6 +66,35 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
     end
   end
 
+  defp handle_preview("image/" <> _ = _content_type, conn, url) do
+    handle_image_or_video_preview(conn, url)
+  end
+
+  defp handle_preview("video/" <> _ = _content_type, conn, url) do
+    handle_image_or_video_preview(conn, url)
+  end
+
+  defp handle_preview(content_type, conn, _url) do
+    send_resp(conn, :unprocessable_entity, "Unsupported content type: #{content_type}.")
+  end
+
+  defp handle_image_or_video_preview(%{params: params} = conn, url) do
+    with {thumbnail_max_width, thumbnail_max_height} <- thumbnail_max_dimensions(params),
+         media_proxy_url <- MediaProxy.url(url),
+         {:ok, thumbnail_binary} <-
+           MediaHelper.ffmpeg_resize(
+             media_proxy_url,
+             %{max_width: thumbnail_max_width, max_height: thumbnail_max_height}
+           ) do
+      conn
+      |> put_resp_header("content-type", "image/jpeg")
+      |> send_resp(200, thumbnail_binary)
+    else
+      _ ->
+        send_resp(conn, :failed_dependency, "Can't handle preview.")
+    end
+  end
+
   defp thumbnail_max_dimensions(params) do
     config = Config.get([:media_preview_proxy], [])
 
@@ -86,27 +115,6 @@ defmodule Pleroma.Web.MediaProxy.MediaProxyController do
     {thumbnail_max_width, thumbnail_max_height}
   end
 
-  defp handle_preview("image/" <> _ = _content_type, %{params: params} = conn, url) do
-    with {thumbnail_max_width, thumbnail_max_height} <- thumbnail_max_dimensions(params),
-         media_proxy_url <- MediaProxy.url(url),
-         {:ok, thumbnail_binary} <-
-           MediaHelper.ffmpeg_resize_remote(
-             media_proxy_url,
-             %{max_width: thumbnail_max_width, max_height: thumbnail_max_height}
-           ) do
-      conn
-      |> put_resp_header("content-type", "image/jpeg")
-      |> send_resp(200, thumbnail_binary)
-    else
-      _ ->
-        send_resp(conn, :failed_dependency, "Can't handle image preview.")
-    end
-  end
-
-  defp handle_preview(content_type, conn, _url) do
-    send_resp(conn, :unprocessable_entity, "Unsupported content type: #{content_type}.")
-  end
-
   defp preview_head_request_timeout do
     Config.get([:media_preview_proxy, :proxy_opts, :head_request_max_read_duration]) ||
       preview_timeout()