Syncing Secrets Across Namespaces using Kubed

It may be required for multiple components across namespaces to consume the same Secret that has been created by a single Certificate. The recommended way to do this is to use kubed with its secret syncing feature.

In order for the target Secret to be synced, the Secret resource must first be created with the correct annotations before the creation of the Certificate, else the Secret will need to be edited instead. The example below shows syncing a certificate belonging to the sandbox Certificate from the cert-manager namespace, into the sandbox namespace.

apiVersion: v1
kind: Namespace
metadata:
  name: sandbox
  labels:
    cert-manager-tls: sandbox # Define namespace label for kubed
---
apiVersion: v1
data:
  ca.crt: ''
  tls.crt: ''
  tls.key: ''
kind: Secret
metadata:
  name: sandbox-tls
  namespace: cert-manager
  annotations:
    kubed.appscode.com/sync: "cert-manager-tls=sandbox" # Sync certificate to matching namespaces
type: kubernetes.io/tls
---
apiVersion: cert-manager.io/v1alpha2
kind: Certificate
metadata:
  name: sandbox
  namespace: cert-manager
spec:
  secretName: sandbox-tls
  commonName: sandbox
  issuerRef:
    name: sandbox-ca
    kind: Issuer
    group: cert-manager.io