HAProxy: How to use "Connection: keep-alive"?

[syndac]

I have an app that uses server sent events with the headers, "Connection: keep-alive" and "Keep-Alive: timeout=60". When I test my app locally, I can tell everything works fine and I can see that the connection stays alive and the response headers in Chrome dev tools show both of those headers.

However, when I deploy my app to my server and access via HAProxy, I can see that the connection immediately closes and the response headers are missing.

What settings in HAProxy control this? Nothing really stands out, though I'm not an expert.

[syndac]

Got it. There's a couple things I had to do:

1. Disable HTTP/2 on the frontend Public Service. I'm not sure why. Connection: keep-alive uses HTTP/1.1 and having HTTP/2 available seems to confuse it
2. To the backend, add the following under Options pass-through:

option http-server-close
http-request set-header Connection keep-alive
http-request set-header Keep-Alive timeout=600

[syndac]

Actually, scratch that (above). Options pass-through on the backend doesn't seem to work. Not sure why. On the "Public interface", I had to add this to the options:

http-request set-header Connection keep-alive if acl_<acl fround in config export>
http-request set-header Keep-Alive timeout=600 if acl_<acl fround in config export>