A chat, a dashboard that updates by itself, live notifications: all of these need a connection that stays open between the browser and the server, instead of the usual request and response. That connection is called a WebSocket. The short answer: on shared hosting, do not count on it. Open connections tie up account resources for as long as anyone is on the site, and the account has process limits. On a VPS it works well, with the proxy set up properly.
What differs from a normal connection
A normal HTTP request lasts milliseconds and frees the server. A WebSocket lasts minutes or hours: each connected visitor is a connection using memory and a “seat” in the process. Ten visitors are ten connections open at once, even if nobody types anything. Hence the difference between where it fits and where it does not.
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In cPanel (shared) |
On a VPS |
| Open connections |
They use limited account resources; a resident websocket server runs into the process limit. |
Only the VPS’s memory and processor limit them. |
| Who handles the proxy |
Passenger. We cannot promise long connections pass through reliably. |
You, with nginx: you must pass the upgrade headers. |
| Socket.IO |
It may start with polling (repeated requests) when the WebSocket does not get through. It works, but it is one request after another. |
It uses the real WebSocket. |
| Recommendation |
Try it with a few users; for real-time at any scale, move. |
The right place. |
On a VPS with nginx, step by step
| 2 |
In the nginx block, add the lines that let the switch from HTTP to WebSocket through:location / {
proxy_pass http://127.0.0.1:3000;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_set_header Host $host;
proxy_read_timeout 3600s;
}proxy_read_timeout matters: by default nginx closes a connection that has had no data for 60 seconds, and idle websockets drop. The value above is an example.
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| 3 |
In the browser, use wss:// (not ws://) when the site is HTTPS, on the same domain. An HTTPS site that opens ws:// is blocked by the browser.
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| 4 |
Reload nginx after validating the configuration: sudo nginx -t and sudo systemctl reload nginx.
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| 5 |
Confirm in the browser: in the developer tools, “Network” tab, filter by “WS”. A connection with status “101” is a working WebSocket.
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If Socket.IO “works” but is slow, it may be falling back to polling without anyone noticing: the “Network” tab shows repeated requests instead of one 101 connection. It is a sign the WebSocket is not getting through, nearly always because the upgrade lines are missing in the proxy.
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Several instances of the application? With more than one process behind the proxy, Socket.IO clients need to stay on the same process or use a shared adapter: the project’s documentation explains. Start with one process. On an unmanaged VPS the maintenance is yours: how far our support goes.
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Need real-time connections? A VPS gives you control of the proxy and the processes.
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