GCPのHTTP(S)ロードバランサでセッションアフィニティを設定する ref: https://qiita.com/h-sakano/items/de23e1d6d4a3e6ce925a

enable-affinity.sh

backend_list=(`gcloud compute backend-services list | awk -v ORS=" " '!/NAME/{gsub("\n"," ",$1); print $1 }'`)
for v in "${backend_list[@]}"
do
    gcloud compute backend-services update "$v" --session-affinity client_ip --global
done

file0.yml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: eccube-ingress
  namespace: 
  annotations:
    kubernetes.io/ingress.class: "gce"
 .
 .
 .