Support/redis config update (#1056)

* Update Redis cache configuration with new Heroku-compatible settings

* Update version of Redis used by local dev environments

docker-compose.yml

@@ -79,7 +79,7 @@ services:
       - ./database_dumps:/database_dumps
 
   redis:
-    image: redis:6
+    image: redis:7.2
     expose:
       - 6379
     logging:

rca/settings/base.py

@@ -176,15 +176,40 @@
 # usually use Redis in production and database backend on staging and dev. In
 # order to use database cache backend you need to run
 # "django-admin createcachetable" to create a table for the cache.
-
+#
 # Do not use the same Redis instance for other things like Celery!
-if "REDIS_URL" in env:
+
+# Prefer the TLS connection URL over non
+REDIS_URL = env.get("REDIS_TLS_URL", env.get("REDIS_URL"))
+
+if REDIS_URL:
+    connection_pool_kwargs = {}
+
+    if REDIS_URL.startswith("rediss"):
+        # Heroku Redis uses self-signed certificates for secure redis conections. https://stackoverflow.com/a/66286068
+        # When using TLS, we need to disable certificate validation checks.
+        connection_pool_kwargs["ssl_cert_reqs"] = None
+
+    redis_options = {
+        "IGNORE_EXCEPTIONS": True,
+        "SOCKET_CONNECT_TIMEOUT": 2,  # seconds
+        "SOCKET_TIMEOUT": 2,  # seconds
+        "CONNECTION_POOL_KWARGS": connection_pool_kwargs,
+    }
+
     CACHES = {
         "default": {
             "BACKEND": "django_redis.cache.RedisCache",
-            "LOCATION": env["REDIS_URL"],
-        }
+            "LOCATION": REDIS_URL + "/0",
+            "OPTIONS": redis_options,
+        },
+        "renditions": {
+            "BACKEND": "django_redis.cache.RedisCache",
+            "LOCATION": REDIS_URL + "/1",
+            "OPTIONS": redis_options,
+        },
     }
+    DJANGO_REDIS_LOG_IGNORED_EXCEPTIONS = True
 else:
     CACHES = {
         "default": {