feat(proof_data_handler): add a health check endpoint to the proof data handler

[pbeza]

What ❔

Add /health endpoint to the proof_data_handler introduced in eca98cc (#1993).

Why ❔

The DevOps team asked for a health check endpoint so the in-cluster load balancer can use it. Details: https://matter-labs-workspace.slack.com/archives/C05MZ0ZUB6Z/p1718801741282109?thread_ts=1718191882.611349&cid=C05MZ0ZUB6Z

Checklist

• PR title corresponds to the body of PR (we generate changelog entries from PRs).
• Tests for the changes have been added / updated.
• Documentation comments have been added / updated.
• Code has been formatted via zk fmt and zk lint.
• Spellcheck has been run via zk spellcheck.

[haraldh]

LGTM

[pbeza]

@popzxc @RomanBrodetski is it too hacky? Should I use health_check crate instead?

[popzxc]

You should use health check instead indeed. Let's not mix approaches.

[popzxc]

Moreover, healthcheck layer is added unconditionally in the node, so isn't it already covered?

[thomasknauth]

Moreover, healthcheck layer is added unconditionally in the node, so isn't it already covered?

Not sure. Proof-data-handler is started like so https://github.com/matter-labs/gitops-kubernetes/blob/main/apps/environments/era-stage-proofs/server-v2/server-v2-proof-data-handler.yaml - does node framework start the health check server automatically? If not, proof data handler should spawn it.

[thomasknauth]

Moreover, healthcheck layer is added unconditionally in the node, so isn't it already covered?

Not sure. Proof-data-handler is started like so https://github.com/matter-labs/gitops-kubernetes/blob/main/apps/environments/era-stage-proofs/server-v2/server-v2-proof-data-handler.yaml - does node framework start the health check server automatically? If not, proof data handler should spawn it.

Never mind. Proof data handler has the health server, so we will integrate with it properly. ✅

[pbeza]

Closing as it turned out there is already a health check endpoint we can reuse.