Provide more info why we don't have any thumbnails to serve

changelog.d/13038.feature

@@ -0,0 +1 @@
+Provide more info why we don't have any thumbnails to serve.

synapse/config/repository.py

@@ -42,6 +42,14 @@
  # method: %(method)s
 """
 
+THUMBNAIL_SUPPORTED_MEDIA_FORMAT_MAP = {
+ "image/jpeg": "jpeg",
+ "image/jpg": "jpeg",
+ "image/webp": "jpeg",
+ "image/gif": "png",
+ "image/png": "png",
+}
+
 HTTP_PROXY_SET_WARNING = """\
 The Synapse config url_preview_ip_range_blacklist will be ignored as an HTTP(s) proxy is configured."""
 
@@ -81,11 +89,18 @@ def parse_thumbnail_requirements(
  method = size["method"]
  jpeg_thumbnail = ThumbnailRequirement(width, height, method, "image/jpeg")
  png_thumbnail = ThumbnailRequirement(width, height, method, "image/png")
- requirements.setdefault("image/jpeg", []).append(jpeg_thumbnail)
- requirements.setdefault("image/jpg", []).append(jpeg_thumbnail)
- requirements.setdefault("image/webp", []).append(jpeg_thumbnail)
- requirements.setdefault("image/gif", []).append(png_thumbnail)
- requirements.setdefault("image/png", []).append(png_thumbnail)
+
+ for format, thumbnail_format in THUMBNAIL_SUPPORTED_MEDIA_FORMAT_MAP.items():
+ requirement = requirements.setdefault(format, [])
+ if thumbnail_format == "jpeg":
+ requirement.append(jpeg_thumbnail)
+ elif thumbnail_format == "png":
+ requirement.append(png_thumbnail)
+ else:
+ raise Exception(
+ "Unknown thumbnail mapping from %s to %s. This is a Synapse problem, please report!"
+ % (format, thumbnail_format)
+ )
  return {
  media_type: tuple(thumbnails) for media_type, thumbnails in requirements.items()
  }

synapse/rest/media/v1/thumbnail_resource.py

@@ -17,11 +17,16 @@
 import logging
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Tuple
 
-from synapse.api.errors import SynapseError
-from synapse.http.server import DirectServeJsonResource, set_cors_headers
+from synapse.api.errors import Codes, SynapseError, cs_error
+from synapse.http.server import (
+ DirectServeJsonResource,
+ set_cors_headers,
+ respond_with_json,
+)
 from synapse.http.servlet import parse_integer, parse_string
 from synapse.http.site import SynapseRequest
 from synapse.rest.media.v1.media_storage import MediaStorage
+from synapse.config.repository import THUMBNAIL_SUPPORTED_MEDIA_FORMAT_MAP
 
 from ._base import (
  FileInfo,
@@ -304,6 +309,14 @@ async def _select_and_respond_with_thumbnail(
  url_cache: True if this is from a URL cache.
  server_name: The server name, if this is a remote thumbnail.
  """
+ logger.debug(
+ "_select_and_respond_with_thumbnail: media_id=%s desired=%sx%s (%s) thumbnail_infos=%s",
+ media_id,
+ desired_width,
+ desired_height,
+ desired_method,
+ thumbnail_infos,
+ )
  if thumbnail_infos:
  file_info = self._select_thumbnail(
  desired_width,
@@ -379,8 +392,40 @@ async def _select_and_respond_with_thumbnail(
  file_info.thumbnail.length,
  )
  else:
+ # This might be because:
+ # 1. We can't create thumbnails for the given media (corrupted or
+ # unsupported file type)
+ # 2. The thumbnailing process never ran or errored out initially
+ # when the media was first uploaded (these bugs should be
+ # reported and fixed).
+ # 3. `dynamic_thumbnails` is disabled (see `homeserver.yaml`) and we
+ # can't try to generate one. If this was enabled, Synapse would
+ # go down a different code path.
  logger.info("Failed to find any generated thumbnails")
- respond_404(request)
+
+ # We could get away with putting this error text directly in the
+ # error below because it never hits this code path otherwise when
+ # `dynamic_thumbnails` is disabled. But it would be good not to
+ # always assume this will be the case in the future so we provide
+ # accurate information to the user.
+ dynamic_thumbnails_disabled_warning_text = ""
+ if not self.dynamic_thumbnails:
+ dynamic_thumbnails_disabled_warning_text = " We also cannot try to generate a new thumbnail because `dynamic_thumbnails` is disabled (see `homeserver.yaml`)."
+
+ respond_with_json(
+ request,
+ 400,
+ cs_error(
+ "Cannot find any thumbnails for the requested media (%r). This might mean the media is not a supported_media_format=(%s) or your media is corrupted and cannot be thumbnailed.%s"
+ % (
+ request.postpath,
+ ", ".join(THUMBNAIL_SUPPORTED_MEDIA_FORMAT_MAP.keys()),
+ dynamic_thumbnails_disabled_warning_text,
+ ),
+ code=Codes.UNKNOWN,
+ ),
+ send_cors=True,
+ )
 
  def _select_thumbnail(
  self,

tests/rest/media/v1/test_media_storage.py

@@ -133,6 +133,7 @@ class _TestImage:
  expected_cropped: Optional[bytes] = None
  expected_scaled: Optional[bytes] = None
  expected_found: bool = True
+ unable_to_thumbnail: bool = False
 
 
 @parameterized_class(
@@ -190,6 +191,7 @@ class _TestImage:
  b"image/gif",
  b".gif",
  expected_found=False,
+ unable_to_thumbnail=True,
  ),
  ),
  ],
@@ -364,18 +366,29 @@ def test_disposition_none(self) -> None:
  def test_thumbnail_crop(self) -> None:
  """Test that a cropped remote thumbnail is available."""
  self._test_thumbnail(
- "crop", self.test_image.expected_cropped, self.test_image.expected_found
+ "crop",
+ self.test_image.expected_cropped,
+ expected_found=self.test_image.expected_found,
+ unable_to_thumbnail=self.test_image.unable_to_thumbnail,
  )
 
  def test_thumbnail_scale(self) -> None:
  """Test that a scaled remote thumbnail is available."""
  self._test_thumbnail(
- "scale", self.test_image.expected_scaled, self.test_image.expected_found
+ "scale",
+ self.test_image.expected_scaled,
+ expected_found=self.test_image.expected_found,
+ unable_to_thumbnail=self.test_image.unable_to_thumbnail,
  )
 
  def test_invalid_type(self) -> None:
  """An invalid thumbnail type is never available."""
- self._test_thumbnail("invalid", None, False)
+ self._test_thumbnail(
+ "invalid",
+ None,
+ expected_found=False,
+ unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+ )
 
  @unittest.override_config(
  {"thumbnail_sizes": [{"width": 32, "height": 32, "method": "scale"}]}
@@ -384,7 +397,12 @@ def test_no_thumbnail_crop(self) -> None:
  """
  Override the config to generate only scaled thumbnails, but request a cropped one.
  """
- self._test_thumbnail("crop", None, False)
+ self._test_thumbnail(
+ "crop",
+ None,
+ expected_found=False,
+ unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+ )
 
  @unittest.override_config(
  {"thumbnail_sizes": [{"width": 32, "height": 32, "method": "crop"}]}
@@ -393,14 +411,22 @@ def test_no_thumbnail_scale(self) -> None:
  """
  Override the config to generate only cropped thumbnails, but request a scaled one.
  """
- self._test_thumbnail("scale", None, False)
+ self._test_thumbnail(
+ "scale",
+ None,
+ expected_found=False,
+ unable_to_thumbnail=self.test_image.unable_to_thumbnail,
+ )
 
  def test_thumbnail_repeated_thumbnail(self) -> None:
  """Test that fetching the same thumbnail works, and deleting the on disk
  thumbnail regenerates it.
  """
  self._test_thumbnail(
- "scale", self.test_image.expected_scaled, self.test_image.expected_found
+ "scale",
+ self.test_image.expected_scaled,
+ expected_found=self.test_image.expected_found,
+ unable_to_thumbnail=self.test_image.unable_to_thumbnail,
  )
 
  if not self.test_image.expected_found:
@@ -457,7 +483,11 @@ def test_thumbnail_repeated_thumbnail(self) -> None:
  )
 
  def _test_thumbnail(
- self, method: str, expected_body: Optional[bytes], expected_found: bool
+ self,
+ method: str,
+ expected_body: Optional[bytes],
+ expected_found: bool,
+ unable_to_thumbnail: bool = False,
  ) -> None:
  params = "?width=32&height=32&method=" + method
  channel = make_request(
@@ -488,6 +518,16 @@ def _test_thumbnail(
  else:
  # ensure that the result is at least some valid image
  Image.open(BytesIO(channel.result["body"]))
+ elif unable_to_thumbnail:
+ # A 400 with a JSON body.
+ self.assertEqual(channel.code, 400)
+ self.assertEqual(
+ channel.json_body,
+ {
+ "errcode": "M_UNKNOWN",
+ "error": "Cannot find any thumbnails for the requested media ([b'example.com', b'12345']). This might mean the media is not a supported_media_format=(image/jpeg, image/jpg, image/webp, image/gif, image/png) or your media is corrupted and cannot be thumbnailed. We also cannot try to generate a new thumbnail because `dynamic_thumbnails` is disabled (see `homeserver.yaml`).",
+ },
+ )
  else:
  # A 404 with a JSON body.
  self.assertEqual(channel.code, 404)