Allow certificate_authority to be a base64 single line string (from Hashicorp Vault)

[NickLarsenNZ]

Is this a BUG REPORT or FEATURE REQUEST?:

• feature

What happened:
Tried setting certificate_authority: ((k8s-ca-cert)) to a variable stored in Vault which is base64 encoded (since Vault doesn't appear to like our multiline PEMs.

What you expected to happen:
It would be nice if the resource could detect a one-line string provided for certificate_authority, and base64 decode it (revealing the multi-line base64 encoded PEM).

How to reproduce it (as minimally and precisely as possible):

- name: k8s-cluster
  type: kubernetes
  source:
    server: ((kubernetes_server_url))
    certificate_authority: ((kubernetes_ca_cert))
    namespace: ((kubernetes_namespace))
    token: ((kubernetes_token))
    # We have to fall back to insecure, or run a task to pull in the b64 string as an environment 
    # variable and decode it, and locate the file in the following steps.
    #insecure_skip_tls_verify: true

Anything else we need to know?:
No

Environment:

• Concourse CI version: (use fly --version): 3.14.1
• kubernetes-resource image version: 1.8
• Others:

[superbrothers]

You can write a multiline text into Vault. See hashicorp/vault#1929 (comment).

[superbrothers]

This issue is inactive, so I'll close it. If you have any problems, please feel free to reopen it.