WebSocket proxying in Nginx - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is WebSocket proxying in nginx?

WebSocket proxying in nginx means forwarding WebSocket connections from clients to backend servers, allowing real-time communication through nginx as a middleman.

beginner

Which nginx directive is essential to support WebSocket proxying?

The directive proxy_set_header Upgrade $http_upgrade; is essential to handle the WebSocket handshake upgrade request properly.

intermediate

Why do we need to set proxy_http_version 1.1; for WebSocket proxying in nginx?

WebSocket requires HTTP/1.1 because it uses the Upgrade header to switch protocols. Setting proxy_http_version 1.1; ensures nginx uses the right HTTP version for the handshake.

intermediate

What headers must nginx forward to support WebSocket connections?

nginx must forward the Upgrade and Connection headers to allow the WebSocket handshake to succeed.

beginner

Show a minimal nginx configuration snippet to proxy WebSocket connections.

location /ws/ {
  proxy_pass http://backend_server;
  proxy_http_version 1.1;
  proxy_set_header Upgrade $http_upgrade;
  proxy_set_header Connection "upgrade";
}

Which HTTP version must nginx use to proxy WebSocket connections?

A HTTP/3

B HTTP/1.0

C HTTP/2

D HTTP/1.1

WebSocket handshake requires HTTP/1.1 because it uses the Upgrade header to switch protocols.

Which header tells the server to switch protocols to WebSocket?

A Upgrade

B Content-Type

C Authorization

D Cache-Control

The Upgrade header requests the server to change the protocol from HTTP to WebSocket.

What value should the Connection header have to support WebSocket proxying?

A keep-alive

B close

C upgrade

D proxy

The Connection header must be set to 'upgrade' to allow the protocol switch for WebSocket.

In nginx, which directive forwards the Upgrade header from client to backend?

A proxy_set_header Upgrade $http_upgrade;

B proxy_pass http://backend;

C proxy_redirect off;

D proxy_buffering off;

This directive forwards the Upgrade header needed for WebSocket handshake.

What happens if nginx does not forward the Upgrade and Connection headers for WebSocket?

A Connection will be faster

B WebSocket connection will fail

C No effect on WebSocket

D nginx will cache the connection

Without these headers, the WebSocket handshake cannot complete, so the connection fails.

Explain how to configure nginx to proxy WebSocket connections.

Think about the headers and HTTP version needed for WebSocket handshake.

Why is it important to set the Connection header to 'upgrade' in WebSocket proxying?

Consider what the Connection header controls in HTTP.