kube cert-manager cert issuer

selfsigned-clusterissuer.yml

---
apiVersion: cert-manager.io/v1
kind: ClusterIssuer
metadata:
  name: selfsigned-cluster-issuer
spec:
  selfSigned: {}

selfsigned-issuer.yml

---
apiVersion: cert-manager.io/v1
kind: Issuer
metadata:
  name: selfsigned-issuer
  namespace: sandbox
spec:
  selfSigned: {}