started using nginx as my back end server, so i have one proxy server where i put haproxy, 3 servers they are responsable to handle the traffic, 3 servers(2 gb, 2 core and 40 gb of SSD each one). recently i started receiving this messages from nginx: "502 Bad Gateway", i have a traffic of 100k daily to my website. I don't know what to do anymore, i did everything and the servers are returning the same error and when i see the log is giving me this information:
"connect() failed (111: Connection refused) while connecting to upstream, client: x.x.x.x, server: _, request: "GET ..."
I don't know if the amount of traffic is to high for this configuration or if the problem is with my nginx configuration, or with my php code. I don't know what to do anymore, i'd like to handle as many requests as possible.
I'm using PHP 7, ubuntu 16.04 and nginx 1.10.
Thanks for your help!