WebSocket 和HTTP虽然是不同协议，但是两者“握手”方式兼容。通过HTTP升级机制，使用HTTP的Upgrade和Connection协议头的方式可以将连接从HTTP升级为WebSocket。
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
标签：Upgrade,HTTP,header,nginx,upgrade,proxy,http,线上,websock From： https://www.cnblogs.com/littlewrong/p/16925007.html