brotli: degrade gracefully when redis is missing

libforget/brotli.py

@@ -5,6 +5,7 @@ from hashlib import sha256
 import redis as libredis
 import os.path
 import mimetypes
+from redis.exceptions import RedisError
 
 
 class BrotliCache(object):
@@ -34,6 +35,7 @@ class BrotliCache(object):
         digest = sha256(body).hexdigest()
         cache_key = 'brotlicache:{}'.format(digest)
 
+        try:
             encbody = self.redis.get(cache_key)
             response.headers.set('brotli-cache', 'HIT')
             if not encbody:
@@ -60,6 +62,8 @@ class BrotliCache(object):
                 response.headers.set('vary', 'accept-encoding')
                 response.set_data(encbody)
                 return response
+        except RedisError:
+            response.headers.set('brotli-cache', 'ERROR')
 
         return response