Command to pull Kuberentes CA in standalone server with TLS Helm deployment example returns empty string

[michael-leon]

Describe the bug
The current command on the deployment example is the following:

kubectl get secret \
  -o jsonpath="{.items[?(@.type==\"kubernetes.io/service-account-token\")].data['ca\.crt']}" \
  | base64 --decode > ${TMPDIR}/vault.ca

However, this no longer works for any Kubernetes cluster version 1.24 and onwards. With the CA now stored in a config map, we need an alternate command to pull the CA.

To Reproduce
Steps to reproduce the behavior:

1. Run the command kubectl get secret \ -o jsonpath="{.items[?(@.type==\"kubernetes.io/service-account-token\")].data['ca\.crt']}" \ | base64 --decode > ${TMPDIR}/vault.ca
2. Run the command cat ${TMPDIR}/vault.ca and observe that no CA certificate was printed out.

Expected behavior
Running cat ${TMPDIR}/vault.ca should print out something like the following:

-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----

Environment:

• Vault Server Version (retrieve with vault status): v.1.18.1+ent
• Vault CLI Version (retrieve with vault version): v1.15.4+ent
• Server Operating System/Architecture: Kubernetes cluster running on AWS EKS w/ Amazon Linux 2

Vault server configuration file(s):
n/a

Additional context
I've made the PR and am creating this issue to attach to it