我们在服务器上面git pull codehub代码的时候会遇到Received HTTP code 504 from proxy after CONNECT，这个报错多数是因为代理配置的问题。
从以下两个方向进行排查：
1. 确认服务器/虚拟机是否配置了全局代理。
检查/etc/profile中是否配置了代理：http_proxy和https_proxy。这里的代理是服务器/虚拟机本身的，相当于全局代理。如果配置了则注释掉之后，执行source /etc/profile。
这时候还有可能没有生效，可以直接执行：
export http_proxy=
export https_proxy=
2. 检查git代理。
git config -l|grep proxy
git config --global --unset-all http.proxy
git config --global --unset-all https.proxy
- Received CONNECT after https proxyreceived connect after https proxy_connect_timeout proxy_connect_timeout策略connect timeout linux https proxy http to connect github https proxy方法linux https received communications milliseconds successfully received sslhandshakeexception protocol_version received server received response upstream