Get tls certificate and key from a kubernetes secret

2020-08-06 - How to extract a tls certificate and keys from a kubernetes secret
Tag: kubernetes

The problem

My use case is to deploy a wildcard certificate that was previously handled by an acme.sh on a legacy lxd containers. Since moving to kubernetes parts of my services I have been using cert-manager to issue letsencrypt certificates for the cluster’s ingresses. Since I am not done migrating everything yet I need a way of getting a certificate out of kubernetes.

The solution

Assuming we are working with a secret named wild.adyxax.org-cert and our namespace is named legacy :

kubectl -n legacy get secret wild.adyxax.org-cert -o json -o=jsonpath="{.data.tls\.crt}" | base64 -d > fullchain.cer
kubectl -n legacy get secret wild.adyxax.org-cert -o json -o=jsonpath="{.data.tls\.key}" | base64 -d > adyxax.org.key