Switch to Photon for thumbnail generation

api/catalog/api/models/mixins.py

@@ -87,7 +87,7 @@ class MediaMixin(models.Model):
     )
 
     # Because all forms of media have a thumbnail for visual representation
-    # For images, this field is not used as images are generated using ``imaginary``.
+    # For images, this field is not used as images are generated using Photon.
     # For audio, this field points to the artwork, or is ``null``.
     thumbnail = models.URLField(
         max_length=1000,

api/catalog/api/utils/photon.py

@@ -0,0 +1,104 @@
+import logging
+from urllib.parse import urlparse
+
+from django.conf import settings
+from django.http import HttpResponse
+from rest_framework import status
+from rest_framework.exceptions import APIException
+
+import django_redis
+import requests
+import sentry_sdk
+
+
+parent_logger = logging.getLogger(__name__)
+
+
+class UpstreamThumbnailException(APIException):
+    status_code = status.HTTP_424_FAILED_DEPENDENCY
+    default_detail = "Could not render thumbnail due to upstream provider error."
+    default_code = "upstream_photon_failure"
+
+
+HEADERS = {
+    "User-Agent": settings.OUTBOUND_USER_AGENT_TEMPLATE.format(
+        purpose="ThumbnailGeneration"
+    )
+}
+
+
+def get(
+    image_url: str,
+    accept_header: str = "image/*",
+    is_full_size: bool = False,
+    is_compressed: bool = True,
+) -> HttpResponse:
+    logger = parent_logger.getChild("get")
+    # Photon options documented here:
+    # https://developer.wordpress.com/docs/photon/api/
+    params = {}
+
+    if not is_full_size:
+        params["w"] = settings.THUMBNAIL_WIDTH_PX
+
+    if is_compressed:
+        params["quality"] = settings.THUMBNAIL_QUALITY
+
+    parsed_image_url = urlparse(image_url)
+
+    if parsed_image_url.query:
+        # No need to URL encode this string because requests will already
+        # pass the `params` object to `urlencode` before it appends it to the
+        # request URL.
+        params["q"] = parsed_image_url.query
+
+    # Photon excludes the protocol so we need to reconstruct the url + port + path
+    # to send as the "path" of the Photon request
+    domain = parsed_image_url.netloc
+    path = parsed_image_url.path
+    upstream_url = f"{settings.PHOTON_ENDPOINT}{domain}{path}"
+
+    try:
+        headers = {"Accept": accept_header} | HEADERS
+        if settings.PHOTON_AUTH_KEY:
+            headers["X-Photon-Authentication"] = settings.PHOTON_AUTH_KEY
+
+        upstream_response = requests.get(
+            upstream_url,
+            timeout=10,
+            params=params,
+            headers=headers,
+        )
+        res_status = upstream_response.status_code
+        content_type = upstream_response.headers.get("Content-Type")
+        logger.debug(
+            "Image proxy response "
+            f"status: {res_status}, content-type: {content_type}"
+        )
+
+        return HttpResponse(
+            upstream_response.content,
+            status=res_status,
+            content_type=content_type,
+        )
+    except requests.ReadTimeout as exc:
+        # Count the incident so that we can identify providers with most timeouts.
+        key = f"{settings.THUMBNAIL_TIMEOUT_PREFIX}{domain}"
+        cache = django_redis.get_redis_connection("default")
+        try:
+            cache.incr(key)
+        except ValueError:  # Key does not exist.
+            cache.set(key, 1)
+
+        sentry_sdk.capture_exception(exc)
+        raise UpstreamThumbnailException(
+            f"Failed to render thumbnail due to timeout: {exc}"
+        )
+    except requests.RequestException as exc:
+        sentry_sdk.capture_exception(exc)
+        raise UpstreamThumbnailException(f"Failed to render thumbnail: {exc}")
+    except Exception as exc:
+        sentry_sdk.capture_exception(exc)
+        raise UpstreamThumbnailException(
+            f"Failed to render thumbnail due to unidentified exception: {exc}"
+        )