Admin tool: add support for reading directory of credential files

[adutra]

Is your feature request related to a problem? Please describe.

The bootstrap command currently takes its input from command line arguments.

But the best for Kubernetes would be to store the bootstrap credentials in a secret, that could look like this:

apiVersion: v1
kind: Secret
metadata:
  name: polaris-bootstrap-creds
data:
  realm1: "client1:secret1"
  realm2: "client2:secret2"

Then the secret could be mounted and each entry would become a file named realm1, realm2 etc. with contents client1:secret1, client2:secret2 etc.

It would be awesome if the bootstrap command could parse the directory and create the credentials from the files.

Describe the solution you'd like

No more annoying messages.

Describe alternatives you've considered

No response

Additional context

No response

[adutra]

This will be useful only if we keep the bootstrap job in the Helm chart. If we decide to get rid of it, this enhancement may not be useful.

[adutra]

After working on this a bit, I think mounting each secret entry as a separate file will be more complex than mounting all the credentials in a single file.