Add readiness and liveness probes in pingsource-mt-adapter

[airycanon]

Problem
The pingsource-mt-adapter currently lacks readiness and liveness probes.

Persona:
System Operator

Exit Criteria
Probes are implemented and correctly indicats the pingsource-mt-adapter is healthy.

[pierDipi]

Would you be interested in contributing this feature?
If you’re interested, I’d be happy to provide any additional information or resources you might need to get started. We have documentation available (development doc), and I’m also here or on CNCF Slack to answer any questions you might have.

/triage accepted
/help

[knative-prow]

@pierDipi:
This request has been marked as needing help from a contributor.

Please ensure the request meets the requirements listed here.

If this request no longer meets these requirements, the label can be removed
by commenting with the /remove-help command.

In response to this:

Would you be interested in contributing this feature?
If you’re interested, I’d be happy to provide any additional information or resources you might need to get started. We have documentation available (development doc), and I’m also here or on CNCF Slack to answer any questions you might have.

/triage accepted
/help

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository.

[pranjalg1331]

Hi I would like to help contribute in this issue.

[airycanon]

@pierDipi Hey, I've got a couple questions hoping you could help me with:

1. I noticed the controller already has some health checks code in there:
   https://github.com/knative/eventing/blob/main/cmd/controller/main.go#L57-L67.
   Would it be possible to extract that code into https://github.com/knative/pkg for reusing?
2. Are there any other components that also need health checks? If so, would it be alright if I implement those as well using the shared code above?

[pierDipi]

@airycanon knative/pkg already runs an health probe server [1], if it's not disabled, maybe we could leverage it?

[1] https://github.com/knative/pkg/blob/25f6002b00f3562c48e4fa6f18882829c61cc73f/injection/sharedmain/main.go#L320-L325