View the current number of nodes in a dev neighborhood via a UI

[tysloan]

Description: This is the first story to incorporate infrastructure observability via an end-to-end implementation of our block explorer, Talib. We should be able to present the current total number of nodes and the number of active nodes via the UI.

Story ROI: This story enables users and node operators to check on infrastructure performance and health via metrics.

As a user, I want to view the current total number of nodes and active nodes in a neighborhood so that I stay informed.

• [ ] Should be achievable via a UI.
• [ ] Should be available from the network API.
• [ ] Should be able to target a specific neighborhood.
• [ ] Should present the current total number of nodes and active nodes.
• [ ] Should present an error message to the user (in UI) if there is an error retrieving the data.
• [ ] Should present a warning to the user (in UI) if there are upstream errors.
• [ ] Should be able to be demoed as an E2E implementation.

[jgryffindor]

• [ ] A custom prometheus exporter needs to be created to export the desired metric data for Talib to query.
• [ ] A DNS endpoint and routing configurations need to be created for Talib to poll the exporter.