can not use resty redis

when i try to connect to the ws server（ws://ip:8081/ws）, it raise error

2021/03/25 00:20:34 [info] 16392#16392: *1 client 113.92.35.59 closed keepalive connection

my nginx.conf content

worker_processes 2;
user root;

events {
    worker_connections 1024;
}

error_log logs/error.log debug;

http {
    server {
        listen 8081 reuseport;
        location /ws {
                        access_by_lua_block {
                                local ngx = ngx
                                local redis = require("resty.redis")
                                ngx.log(ngx.INFO, "access stage")
                                local red = redis:new()
                                local ok, err = red:connect("127.0.0.1", 6379)
                                if not ok then
                                ngx.exit(ngx.HTTP_UNAUTHORIZED)
                                end
                        }
        }

    }
}

Start with the /ws location and its access_by_lua_block in the supplied nginx.conf, then reproduce the request while checking the shown Nginx error output and the resty.redis connection result. Done means the WebSocket request and Redis connection work together without the reported connection failure, with the cause identified from the available logs.