K8S with Traefik and HAP not getting real client IP on pods - kubernetes

Question

I have an external LB using HAProxy in order to have a HA k8s cluster. My cluster is in K3s from Rancher and it's using Traefik LB internally.
I'm currently facing an issue where in my pods I'm getting the Traefik IP instead of the real client IP.
HAP Configuration:
# Ansible managed
defaults
maxconn 1000
mode http
log global
option dontlognull
log stdout local0 debug
option httplog
timeout http-request 5s
timeout connect 5000
timeout client 2000000
timeout server 2000000
frontend k8s
bind *:6443
bind *:80
bind *:443
mode tcp
option tcplog
use_backend masters-k8s
backend masters-k8s
mode tcp
balance roundrobin
server master01 master01.k8s.int.ntw
server master02 master02.k8s.int.ntw
# end Ansible managed
Traefik Service:
apiVersion: v1
kind: Service
metadata:
annotations:
meta.helm.sh/release-name: traefik
meta.helm.sh/release-namespace: kube-system
service.beta.kubernetes.io/do-loadbalancer-enable-proxy-protocol: "true"
labels:
app: traefik
app.kubernetes.io/managed-by: Helm
chart: traefik-1.81.0
heritage: Helm
release: traefik
spec:
clusterIP: 10.43.250.142
clusterIPs:
- 10.43.250.142
externalTrafficPolicy: Local
ports:
- name: http
nodePort: 32232
port: 80
protocol: TCP
targetPort: http
- name: https
nodePort: 30955
port: 443
protocol: TCP
targetPort: https
selector:
app: traefik
release: traefik
sessionAffinity: None
type: LoadBalancer
status:
loadBalancer:
ingress:
- ip: 10.0.1.1
- ip: 10.0.1.11
- ip: 10.0.1.12
- ip: 10.0.1.2
With this configurations I never get my real IP on the pods, during some research I saw that people recommend to use send-proxy in the HAP like this:
server master01 master01.k8s.int.ntw check send-proxy-v2
server master02 master02.k8s.int.ntw check send-proxy-v2
But when I do so, all my cluster communication returns ERR_CONNECTION_CLOSED.
If I'm looking at it correctly, this means its going from the HAP to the cluster and the cluster is somewhere rejecting the traffic.
Any clues what I'm missing here?
Thanks

Answer 1

Well you have two options.
use proxy protocol
use X-Forwarded-For header
Option 1: proxy protocol
This option requires that both sites HAProxy and Traefik uses the proxy protocol, that's the reason why the people recommend "send-proxy-v2".
This requires also that all other clients which want to connect to Traefik MUST also use the proxy protocol, if the clients does not use the proxy protocol then you will get what you get a communication error.
As you configured HAProxy in TCP mode is this the only option to get the client ip to Traefik.
Option 2: X-Forwarded-For
I personally would use this option because it makes it possible to connect to traefik with any http(s) client.
This requires that you use the HTTP mode in haproxy and some more parameters like option forwardfor.
# Ansible managed
defaults
maxconn 1000
mode http
log global
option dontlognull
log stdout local0 debug
option httplog
timeout http-request 5s
timeout connect 5s
timeout client 200s
timeout server 200s
# send client ip in the x-forwarded-for header
option forwardfor
frontend k8s
bind *:6443 v4v6 alpn h2,http/1.1 ssl ca-file /etc/haproxy/letsencryptauthorityx3.pem crt /etc/ssl/haproxy/
bind *:80 v4v6 alpn h2,http/1.1 ssl ca-file /etc/haproxy/letsencryptauthorityx3.pem crt /etc/ssl/haproxy/
bind *:443 v4v6 alpn h2,http/1.1 ssl ca-file /etc/haproxy/letsencryptauthorityx3.pem crt /etc/ssl/haproxy/
use_backend masters-k8s
backend masters-k8s
balance roundrobin
server master01 master01.k8s.int.ntw check
server master02 master02.k8s.int.ntw check
# end Ansible managed
In the File "/etc/haproxy/letsencryptauthorityx3.pem" are the CA's for the backends, in the directory "/etc/ssl/haproxy/" are the certificates for the frontends.
Please take a look into the documentation about the crt keyword.
You have also to configure traefik to allow the header from haproxy forwarded-headers