实验环境下，ingress controller 下游的LB使用的是nginx，配置如下：

ingress.conf:

upstream ingress-443 {
  server 10.4.7.106:443 max_fails=1 fail_timeout=30s ;
  server 10.4.7.105:443 max_fails=1 fail_timeout=30s ;
  server 10.4.7.104:443 max_fails=1 fail_timeout=30s ;
}
upstream ingress-80 {
  server 10.4.7.106:80 max_fails=1 fail_timeout=30s ;
  server 10.4.7.105:80 max_fails=1 fail_timeout=30s ;
  server 10.4.7.104:80 max_fails=1 fail_timeout=30s ;
}
server {
  listen 0.0.0.0:443 ;
  proxy_protocol on ;
  proxy_connect_timeout 2s;
  proxy_next_upstream on;
  proxy_next_upstream_timeout 5;
  proxy_next_upstream_tries 1;
  proxy_pass ingress-443;
  access_log /var/log/nginx/kube-ingress.log proxy;
}
server {
  listen 0.0.0.0:80 ;
  proxy_protocol on ;
  proxy_connect_timeout 2s;
  proxy_next_upstream on;
  proxy_next_upstream_timeout 5;
  proxy_next_upstream_tries 1;
  proxy_pass ingress-80;
  access_log /var/log/nginx/kube-ingress.log proxy;
}