Server sent events stopped work after enabling ssl on proxy

Question

I made web project, that based on Tomcat and Nginx in front of him.
Had to work hard to make it work without errors.
However, when I added ssl to nginx. Stopped working

Answer 1

For SSE to work properly, you must make sure nothing is getting cached or buffered: not in your script (e.g. in PHP we have the @ob_flush();@flush() idiom), not at your web server, and not at any intermediate proxies or firewalls.

You say you commented out all the nginx commands to do with buffering, but commenting out means it will use the defaults. E.g. the default for proxy_buffering is on. I would suggest explictly specifying them to make sure all buffering and caching is switched off.

proxy_buffering off;
proxy_buffer_size 0;
proxy_cache off;

I would also consider explicitly setting the timeouts high, rather than commenting them out. The definition of "high" depends on your application. E.g. if it is always sending data every couple of seconds, the defaults will be fine. But if you are using SSE for irregular data, and there might sometimes be half an hour between messages, make sure the timeouts are more than half an hour.

UPDATE: Apparently (see the comments) adding response.addHeader("X-Accel-Buffering", "no"); (i.e. to the server-side process, not to the proxy config) fixes the problem. This makes sense, as that was added specifically for SSE and similar HTTP streaming, see the nginx documentation. It does imply the above Nginx configuration should also work (the OP has reported that it does not). But, on the other hand, using a header to disable buffering on a per-connection basis feels like a better solution anyway.