Tiny add back router worker health metric and fix init state

[fzyzcjy]

Motivation

Modifications

Accuracy Tests

Benchmarking and Profiling

Checklist

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[gemini-code-assist]

Summary of Changes

Hello @fzyzcjy, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request reintroduces a previously missing worker health metric within the SGLang model gateway. It defines a new gauge metric, smg_worker_health, which tracks the health status of individual workers (1 for healthy, 0 for unhealthy) and integrates its update into the worker's health setting mechanism. This enhancement improves the observability of worker states, providing clearer insights into the operational status of the router's components.

Highlights

• Worker Health Metric Reintroduction: Reintroduces a worker health metric (smg_worker_health) to the router, allowing for better observability of individual worker statuses.
• Metric Definition: Defines a new gauge metric smg_worker_health that reports 1.0 for healthy workers and 0.0 for unhealthy workers, tagged by worker URL.
• Health Status Update Integration: Integrates the metric update into the set_healthy function of the BasicWorker, ensuring the metric is updated whenever a worker's health status changes.

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[gemini-code-assist]

Code Review

This pull request re-introduces a gauge metric smg_worker_health to track worker health status. The implementation is straightforward, but I've noted one medium-severity issue: the metric is not set when a worker is initialized, which could lead to incomplete monitoring data for workers that never change their health state. I've left a specific comment with a recommendation to address this.

[fzyzcjy]

/tag-and-rerun-ci