I need to understand what is Keepalive in nginx.conf which is in a nginx-ingress-controller container (etc/nginx/nginx.conf). What does Keepalive do to the upstream server (i.e load balancers)?
keepalived enables virtualip in kubernetes cluster. It is very useful particularly when you need to setup highly available kubernetes cluster.
it helps you enable high availability for master servers. you need to install keepalived on each of the master machine. all the nodes ( kubelets AND kube-proxies running on each node ) can reach the master using the VIrtualIP. if one of the master server is crashed the virtualip gets failed over to another available master. that way you will achieve high availability for master servers in k8s