core/cert-manager.yaml

apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: letsencrypt-production
  namespace: cert-manager
spec:
  acme:
    email: acme@van-hemmen.com
    # We use the staging server here for testing to avoid hitting
    server: https://acme-v02.api.letsencrypt.org/directory
    privateKeySecretRef:
      # if not existing, it will register a new account and stores it
      name: letsencrypt-production
    solvers:
      - http01:
          # The ingressClass used to create the necessary ingress routes
          ingress:
            class: traefik