From cdc929d95e86e6fa126c66a31244305980efa26c Mon Sep 17 00:00:00 2001
From: Dhruv Bhanushali <dhruv_b@live.com>
Date: Sat, 16 Dec 2023 10:30:51 +0400
Subject: [PATCH] Make caching of image extension Redis-resilient

---
 api/api/utils/image_proxy/extension.py  | 23 ++++++++++++++++++++---
 api/test/unit/utils/test_image_proxy.py | 24 +++++++++++++++++++++---
 2 files changed, 41 insertions(+), 6 deletions(-)

diff --git a/api/api/utils/image_proxy/extension.py b/api/api/utils/image_proxy/extension.py
index 2f2612022c3..4c6537b34e1 100644
--- a/api/api/utils/image_proxy/extension.py
+++ b/api/api/utils/image_proxy/extension.py
@@ -1,3 +1,4 @@
+import logging
 from os.path import splitext
 from urllib.parse import urlparse
 
@@ -5,16 +6,23 @@
 import django_redis
 import sentry_sdk
 from asgiref.sync import sync_to_async
+from redis.exceptions import ConnectionError
 
 from api.utils.aiohttp import get_aiohttp_session
 from api.utils.asyncio import do_not_wait_for
 from api.utils.image_proxy.exception import UpstreamThumbnailException
 
 
+parent_logger = logging.getLogger(__name__)
+
+
 _HEAD_TIMEOUT = aiohttp.ClientTimeout(10)
 
 
 async def get_image_extension(image_url: str, media_identifier) -> str | None:
+    logger = parent_logger.getChild("get_image_extension")
+    is_redis_reachable = True
+
     cache = django_redis.get_redis_connection("default")
     key = f"media:{media_identifier}:thumb_type"
 
@@ -22,8 +30,12 @@ async def get_image_extension(image_url: str, media_identifier) -> str | None:
 
     if not ext:
         # If the extension is not present in the URL, try to get it from the redis cache
-        ext = await sync_to_async(cache.get)(key)
-        ext = ext.decode("utf-8") if ext else None
+        try:
+            ext = await sync_to_async(cache.get)(key)
+            ext = ext.decode("utf-8") if ext else None
+        except ConnectionError:
+            logger.warning("Redis connect failed, cannot get cached image extension.")
+            is_redis_reachable = False
 
     if not ext:
         # If the extension is still not present, try getting it from the content type
@@ -37,7 +49,12 @@ async def get_image_extension(image_url: str, media_identifier) -> str | None:
             else:
                 ext = None
 
-            do_not_wait_for(sync_to_async(cache.set)(key, ext if ext else "unknown"))
+            if is_redis_reachable:
+                do_not_wait_for(
+                    sync_to_async(cache.set)(key, ext if ext else "unknown")
+                )
+            else:
+                logger.warning("Redis connect failed, cannot cache image extension.")
         except Exception as exc:
             sentry_sdk.capture_exception(exc)
             raise UpstreamThumbnailException(
diff --git a/api/test/unit/utils/test_image_proxy.py b/api/test/unit/utils/test_image_proxy.py
index e530751631c..cc9983736f1 100644
--- a/api/test/unit/utils/test_image_proxy.py
+++ b/api/test/unit/utils/test_image_proxy.py
@@ -529,9 +529,18 @@ def test_photon_get_raises_by_not_allowed_types(photon_get, image_type):
         ({"Content-Type": "unknown"}, b"unknown"),
     ],
 )
+@cache_availability_params
 def test_photon_get_saves_image_type_to_cache(
-    photon_get, redis, headers, expected_cache_val
+    photon_get,
+    headers,
+    expected_cache_val,
+    is_cache_reachable,
+    cache_name,
+    request,
+    caplog,
 ):
+    cache = request.getfixturevalue(cache_name)
+
     image_url = TEST_IMAGE_URL.replace(".jpg", "")
     image = ImageFactory.create(url=image_url)
     media_info = MediaInfo(
@@ -544,5 +553,14 @@ def test_photon_get_saves_image_type_to_cache(
         with pytest.raises(UnsupportedMediaType):
             photon_get(media_info)
 
-        key = f"media:{image.identifier}:thumb_type"
-        assert redis.get(key) == expected_cache_val
+    key = f"media:{image.identifier}:thumb_type"
+    if is_cache_reachable:
+        assert cache.get(key) == expected_cache_val
+    else:
+        assert all(
+            message in caplog.text
+            for message in [
+                "Redis connect failed, cannot get cached image extension.",
+                "Redis connect failed, cannot cache image extension.",
+            ]
+        )