"TCP SERVICES frontends" uses only 1 certificate

[GuilhermeAbraham]

We want to have 2 tcp frontends for the same backend.

Steps to reproduce the problem

1. Configure a ingress for TCP services with 2 hosts and different certificates for each host
2. Execute openssl s_client -showcerts -servername HOST -connect HOST:443 </dev/nul for each host
3. Check only 1 certificate gets returned

Environment information
HAProxy Ingress version: v0.14.7

This is our ingress:

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: "haproxy-mtls"
    haproxy-ingress.github.io/tcp-service-port: "443"
    haproxy-ingress.github.io/secure-backends: "false"
    haproxy-ingress.github.io/secure-verify-ca-secret: "namespace1/mtls-ca"
    haproxy-ingress.github.io/auth-tls-secret: "namespace1/mtls-ca"
    haproxy-ingress.github.io/auth-tls-verify-client: "on"
    haproxy-ingress.github.io/ssl-options-backend: ""
    haproxy-ingress.github.io/tcp-service-proxy-protocol: "v2"
    haproxy-ingress.github.io/backend-check-interval: "2s"
    haproxy-ingress.github.io/proxy-protocol: "v2"
    haproxy-ingress.github.io/health-check-port: "1885"
  name: mtls
  namespace: namespace1
spec:
  rules:
    - host: mtls.domain.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: do-stuff
                port:
                  name: mqtt-do-stuff
    - host: mtls.old.domain.com
      http:
        paths:
          - path: /
            pathType: Prefix
            backend:
              service:
                name: do-stuff
                port:
                  name: mqtt-do-stuff
  tls:
    - hosts:
        - mtls.domain.com
      secretName: root
    - hosts:
        - mtls.old.domain.com
      secretName: mqtt

This is how the configuration looks like:

# #
#     TCP SERVICES frontends
#
frontend _front_tcp_443
    bind :443 ssl crt /var/lib/haproxy/crt/root.pem ca-file /var/lib/haproxy/cacerts/mtls-ca.pem verify required
    mode tcp
    option tcplog
    tcp-request content set-var(req.tcpback) ssl_fc_sni,lower,map_str(/etc/haproxy/maps/_tcp_sni_443__exact.map)
    use_backend %[var(req.tcpback)] if { var(req.tcpback) -m found }

In summary, notice that even if you have 2 hosts and 2 secrets on the template you always only consider 1 crt instead of a crt-list.

Also, relate to #1109 where you removed SNI from the mappings, found it interesting SNI maps still being used on TCP, it don't impact what we doing but maybe you want to consider if this needs to be changed?

Thanks in advance, let me know if I can do anything to help and/or provide clarification.