Create Kubernetes Secret declaratively

apiVersion: v1
kind: Secret
metadata:
  name: app-secret
data:
  APP_MODE: cHJvZA==
  APP_PASS: cGFzc3dvcmQ=

The data values are:

APP_MODE: prod
APP_PASS: password

and could be encoded using this commands:

echo -n "prod" | base64
cHJvZA==
echo -n "password" | base64
cGFzc3dvcmQ=

Remember that secrets encode data in base64 format. Anyone with the base64 encoded secret can easily decode it. As such the secrets can be considered as not very safe and should not be stored in a git repository.