ingress-subdomain-as-header

apiVersion: networking.k8s.io/v1 
kind: Ingress
metadata:
  name: {{ template "name" . }}
  labels:
    app: {{ template "name" . }}
    chart: "{{ .Chart.Name }}-{{ .Chart.Version }}"
    release: "{{ .Release.Name }}"
    heritage: "{{ .Release.Service }}"
  annotations:
    kubernetes.io/ingress.class: "nginx"
    kubernetes.io/tls-acme: "{{.Values.acme}}"
    nginx.ingress.kubernetes.io/affinity: "cookie"
    nginx.ingress.kubernetes.io/session-cookie-name: "route"
    nginx.ingress.kubernetes.io/session-cookie-expires: "172800"
    nginx.ingress.kubernetes.io/session-cookie-max-age: "172800"
    nginx.ingress.kubernetes.io/limit-rps: "100"
    nginx.ingress.kubernetes.io/proxy-body-size: 500m
    nginx.ingress.kubernetes.io/proxy-connect-timeout: "600"
    nginx.ingress.kubernetes.io/proxy-send-timeout: "600"
    nginx.ingress.kubernetes.io/proxy-read-timeout: "600"
    nginx.ingress.kubernetes.io/use-regex: "true"
    nginx.ingress.kubernetes.io/configuration-snippet: |   
      proxy_set_header subdomain $subdomain;
    nginx.ingress.kubernetes.io/server-snippet: |
      server_name ~^(?<subdomain>.*)\.{{.Values.host}}$;

spec:
  rules:
  - host: "*.{{.Values.host}}"
    http:
      paths:
      - path: /
        pathType: "Prefix"
        backend:
          service:
            name: {{ template "name" . }}
            port:
              number: 80
  tls:
  - secretName: "{{ .Values.tlsSecretName }}"
    hosts:
    - "{{.Values.host}}"