Base64 decode the K8 secrets on volume mount - kubernetes

Question

My k8.yaml looks like this.
apiVersion: apps/v1
kind: Deployment
metadata:
name: <...>
namespace: <...>
spec:
template:
spec:
containers:
- name: <...>
image: <...>
volumeMounts:
- name: decoded
mountPath: /usr/src/app/decoded
volumes:
- name: decoded
secret:
secretName: base64-secret
defaultMode: 0755
Variables in base64-secret k8 secrets are base64 encoded. Is there anyway to decode the content when they are mounted to a path using the k8 yaml configuration?
So far, the only way I could think of is using a script to decode when the container starts.
FYI: the secret type is Generic

Answer 1

It can be done using base64 -d command (-d : decode)
Example :
#secret name samplesecret
kubectl get secret samplesecret
NAME TYPE DATA AGE
samplesecret Opaque 3 4m20s
#get all the keys in the secrets (keys wont be encoded but values will be encoded):
kubectl get secret samplesecret -o jsonpath='{.data}'
{"key1":"dmFsdWU=","key2":"dmFsdWUy","key3":"dmFsdWUz"}
#now decode the desired key's value by piping it to base64 -d:
kubectl get secret samplesecret -o jsonpath='{.data.key1}' | base64 -d
value
kubectl get secret samplesecret -o jsonpath='{.data.key2}' | base64 -d
value2
kubectl get secret samplesecret -o jsonpath='{.data.key3}' | base64 -d
value3
# if you want to iterate through all the keys & display their values decoded :
kubectl get secret <secretname> -o go-template='{{range $k,$v := .data}}{{"### "}}{{$k}}{{"\n"}}{{$v|base64decode}}{{"\n\n"}}{{end}}'
kubectl get secret samplesecret -o go-template='{{range $k,$v := .data}}{{"### "}}{{$k}}{{"\n"}}{{$v|base64decode}}{{"\n\n"}}{{end}}'
### key1
value
### key2
value2
### key3
value3