Detailed check for health check endpoint '/readyz'

[anencore94]

/kind feature

Describe the solution you'd like
[A clear and concise description of what you want to happen.]

On #1934, we issue there might need to determine whether the katib controller is ready or not more sophistically.
But, for now, I don't have any idea for what we need to check necessary, and how often we need to check it.

Ref)

• [feat] health check for katib-controller #1934 (comment)
• [feat] health check for katib-controller #1934 (comment)

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

---

Love this feature? Give it a 👍 We prioritize the features with the most 👍

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[tenzen-y]

/lifecycle frozen

[Sheethalsheethu]

After coming across the issue regarding the need for a health check system for the Katib controller, I believe implementing the following checks will ensure the system's readiness and stability. Below are my suggestions:

1. Kubernetes Platform Health (Pre-Deployment)
   Before deploying the Katib controller, we should ensure the Kubernetes environment is healthy:

Cluster Health: Verify control plane and nodes are operational.
Network & Storage: Ensure network communication and persistent storage are available.
Node Resources: Confirm enough CPU, memory, and storage resources on worker nodes.
These checks should happen once during system startup to ensure the platform is ready for deployment.

2. Katib Controller Health (Post-Deployment)
   Once the Kubernetes platform is verified, we need to confirm that the Katib controller is healthy:

Service Availability: Ensure the Katib controller is running and responsive.
Dependencies: Check that any required services (e.g., databases, APIs) are available.
Configuration: Confirm environment variables and configurations are correct for the Katib controller to work properly.
These checks should also occur once when the Katib controller is initialized.

Frequency of Health Checks
Initial Health Checks: Run once when the system or controller starts.
Optional Periodic Health Checks: If required, health checks can be run periodically (every 5-10 minutes) during runtime, but this is optional depending on the application’s needs.