Hi,
Le 02/02/2016 23:32, Nick Ramirez a écrit :
Greetings, I am trying to figure out why, in roundrobin mode, with http-keep-alive set (which should be the deafult anyway), the connection doesn't seem to be kept open to the backend server. Here is my HAproxy config where I've set the keep-alive timeout to 5 seconds: defaults timeout connect 5s timeout client 120s timeout server 120s timeout http-request 5s timeout http-keep-alive 5s option http-keep-alive frontend http mode http bind *:80 default_backend servers1 backend servers1 mode http balance roundrobin server web1 web1:80 check server web2 web2:80 check server web3 web3:80 check Using Wireshark, it looks like, from the client perspective, the client is reusing the same socket connection to HAProxy's frontend until the timeout expires. At least, I think so. Source port reports as "port 80" and destination port reports as some high numbered port, say 58000. And over subsequent refreshes during the timeout period, it keeps using those same ports. So the keep-alive appears to be working between client and frontend. However, I added an image to the Web page to see which backend server would serve it (my little test to make sure the connection to the server on the backend was being kept the same), and to see if it would be a different server than the one that served the HTML...and it was different. In roundrobin mode, two different backend servers served up content to the same client, even though I had keep-alive enabled. I changed the timeout period to be 25 seconds and, same behavior.
As you don't use any persistance (cookie, stick tables, source balancing, ...), it is a valid scenario : the connection is reused only if the roundrobin algorithm choose the same server for the next request (which can randomly happen depending on the traffic). But, there is an option to tell haproxy should try to reuse the previous server connection : option prefer-last-server
http://cbonte.github.io/haproxy-dconv/configuration-1.6.html#option%20prefer-last-server
This all seems to me like keep-alive is not working between frontend and backend. Like, it keeps the connection between client and frontend, but not between frontend and backend. This is the behavior I would expect if I had set option http-server-close, but not when using option http-keep- alive which should keep the connection to the server open.
-- Cyril Bonté
