How to use Nginx to reverse proxy docker containers running code-server?

[ghost]

I'm running code-server with a docker container. If there's only one container, I used the follow configuration directives:
proxy_pass http://ip:port;
proxy_http_version 1.1;
proxy_set_header Host $http_host;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection upgrade;
And it works normally.
But if I have many containers, and each has its own IP and Port, I used the follow configuration directives:
proxy_pass http://$http_x_ip:$http_x_port;
proxy_http_version 1.1;
proxy_set_header Host $http_host;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection upgrade;
I passed IP and Port in request header, and it can access the code-server but with such an error:
"An unexpected error occurred that requires a reload of this page. The workbench failed to connect to the server (Error: WebSocket close with status code 1006)"
So, what can I do to fix it?
Thanks a lot!

[eliluong]

You might need to also add proxy_set_header Accept-Encoding gzip;

Here is thread with lots of nginx-related information: #4443