ingress.yml

apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  name: phpinfo
  namespace: phpinfo
  annotations:
    certmanager.k8s.io/issuer: letsencrypt
    kubernetes.io/tls-acme: 'true'
spec:
  tls:
  - hosts:
    - phpinfo.domain.com
    secretName: tls
  rules:
    - host: phpinfo.domain.com
      http:
        paths:
        - backend:
            serviceName: phpinfo
            servicePort: 80

issuer.yml

apiVersion: certmanager.k8s.io/v1alpha1
kind: Issuer
metadata:
  name: letsencrypt
  namespace: phpinfo
spec:
  acme:
    server: https://acme-v02.api.letsencrypt.org/directory
    email: admin@domain.com
    privateKeySecretRef:
      name: letsencrypt
    http01: {}