feat(derive): Metrics

[refcell]

Description

Metrics in kona-derive are a set of prometheus types that are spread across the pipeline stages using helper macros. The helper macros handle feature flagging since metrics are not available by default.

We want to provide a more stable and structured way for pipeline consumers to handle metrics.
Each stage should define its own metrics through a trait abstraction.
By default, pipeline construction will provide no-op implementations.

Output

• Remove current metrics in kona-derive.
• Introduce stage-wise metricer traits with Noop Implementations.
• Introduce a metrics module with prometheus-backed metric collection.

[steph-rs]

hey, can I take it? 🙏

[refcell]

hey, can I take it? 🙏

That would be excellent @steph-rs - I've assigned you to the issue! We've already removed metrics from kona-derive and kona-derive-alloy. (See linked PRs below). The next step is basically to introduce a metricer trait that is able to consume metrics. I'd suggest to start by adding metrics to the top-level DerivationPipeline. Some useful metrics may be:

• Metrice the step results in the DerivationPipeline::step method.
• Metrice the number of times the pipeline received Reset signal.
• Metrice the number of times the pipeline received a FlushChannel signal.

Feel free to ask for help or guidance whenever. Some motivation for why we need this is to provide a dashboard in op-rs with metrics for the derivation pipeline part of the consensus client (aka hera binary).

Metrics removal PRs for reference.

• Remove metrics from kona-derive-alloy: chore(derive-alloy): Remove metrics + cleanup #748
• Remove metrisc from kona-derive: feat(derive): Remove metrics #743