add redis to accelerate access of minio (#482)

### What problem does this PR solve?

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

conf/mapping.json

@@ -1,7 +1,7 @@
  {
   "settings": {
     "index": {
-      "number_of_shards": 4,
+      "number_of_shards": 2,
       "number_of_replicas": 0,
       "refresh_interval" : "1000ms"
     },