One of the critical parts of Jenkins automation is the management of credentials. Jenkins uses hudson.util.Secret and master.key files to encrypt all the credentials. The two are stored in secrets directory inside Jenkins home directory. The credentials we uploaded or pasted are stored in credentials.yml. On top of those, each plugin (for example, Google cloud) can add their files with credentials.
We need the credentials as well and the secrets if we are to automate Jenkins setup. One solution could be to generate the secrets, use them to encrypt credentials, and store them as Kubernetes secrets or config maps. However, that is a tedious process.
Since we already have a fully configured Jenkins, we might just as well copy the files. We'll persist the files we need to the local directories cluster/jenkins and cluster/jenkins...
