Feature: Exposing Prometheus metrics to user-defined interface

[tgerring]

Changes

• Add --Metrics.ExposeHost option and pass that to NethermindKestrelMetricServer so a hostname other than localhost can be exposed. Defaults to 127.0.0.1 EDIT: to "+" since this is the current default behavior without an option.

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Description

Testing

Requires testing

• Yes
• No

I have only compiled this on my dev laptop and not run this on my production node yet. Therefore I am looking for early feedback to my commits until that can be completed. It would be good to verify the passed address matches what is printed in the logs (instead of 127.0.0.1, as it currently shows). as well as, ensuring that the hostname:port can be accessed, i.e. from dev laptop curl

If yes, did you write tests?

• Yes
• No

Notes on testing

Built Nethermind.Runner, correcting all errors and verified the new CLI option was available (when spelled correctly)

Documentation

Requires documentation update

• Yes
• No

Metrics documentation is already marked for needing update

Requires explanation in Release Notes

• Yes
• No

Add Metrics.ExposeHost configuration option. Defaults to 127.0.0.1. Allows Prometheus metrics to be exposed on an interface other than localhost.

[tgerring]

Built this against .NET 8.0 on Ubuntu 22.04. Resulting binary was able to consume Metrics.ExposeHost and now correctly exposes metrics to external HTTP requests, including Prometheus directly with config like so:

  - job_name: nethermind
    metrics_path: /metrics
    static_configs:
      - targets: ['10.10.3.111:6061']

The Nethermind Grafana dashboard now loads correctly, as the data is able to be collected by Prometheus running on a separate host.

[benaadams]

@tgerring thank you for your contribution