使用Ingress-nginx，Iptables和MetalLb在Kubernetes裸机上保留源IP

问题描述

我设置了一个具有一个主节点和一个工作节点的Kubernetes集群。

通过从主机到类型为MetalBb的LoadBalancer类型的ingress-nginx服务进行NAT，将流量路由到群集中：

#!/bin/bash

iptables -t nat -A PREROUTING -p tcp -i eth0 --dport 80 -j DNAT --to-destination "$1":80
iptables -A FORWARD -p tcp -d "$1" --dport 80 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

$1是ingress-nginx的外部IP。

apiVersion: v1
kind: Service
metadata:
  name: ingress-nginx
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  type: LoadBalancer
  externalTrafficPolicy: Local
  ports:
    - name: http
      port: 80
      targetPort: 80
      protocol: TCP
    - name: https
      port: 443
      targetPort: 443
      protocol: TCP
  selector:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

这时，如果我查看ingress-nginx pod的日志，就可以看到真实的源IP地址。

问题是，当我检查下游应用程序的日志（从入口获取流量）时，源IP是入口Pod的IP。

kind: Ingress
metadata:
  namespace: laurkyt
  name: laurkyt-ingress
  annotations:
    cert-manager.io/cluster-issuer: "letsencrypt-prod"
    nginx.ingress.kubernetes.io/backend-protocol: "HTTPS"
    nginx.ingress.kubernetes.io/affinity: cookie
    nginx.ingress.kubernetes.io/session-cookie-hash: sha1
    nginx.ingress.kubernetes.io/session-cookie-name: REALTIMESERVERID
    nginx.ingress.kubernetes.io/proxy-connect-timeout: "3600"
    nginx.ingress.kubernetes.io/proxy-read-timeout: "3600"
    nginx.ingress.kubernetes.io/proxy-send-timeout: "3600"
    nginx.ingress.kubernetes.io/send-timeout: "3600"
    nginx.ingress.kubernetes.io/proxy-body-size: 50m
    ingress.kubernetes.io/proxy-body-size: 50m
spec:
  tls:
  - hosts:
    - example.com
    - '*.example.com'
    secretName: wildcard-example-com
  rules:
  - host: example.com
    http:
      paths:
      - backend:
          serviceName: laurkyt
          servicePort: 443

apiVersion: v1
kind: Service
metadata:
  namespace: laurkyt
  name: laurkyt
  labels:
    app: laurkyt
spec:
  externalTrafficPolicy: Local
  ports:
  - port: 80
    targetPort: 80
    name: "http"
  - port: 443
    targetPort: 443
    name: "https"
  selector:
    app: laurkyt
    tier: laurkyt

有没有人知道我想在后端Pod上保留源IP吗？

解决方法

由于入口是第4层以上的代理。您无法在第3层IP协议中保留SRC IP。最好的办法是，我认为Nginx Ingress已默认设置为将“ X-Forwarded-For”标头放在任何HTTP转发中。

您的应用程序假设要记录X-Forwarded-For标头。