fix: correct SGLang metrics prefix from sglang_ to sglang:

[keivenchang]

Overview:

SGLang metrics natively use the sglang: prefix (with colon), not sglang_ (with underscore).

Details:

• Removed add_prefix="sglang_" parameter from setup_prometheus_registry() in publisher.py to preserve native sglang: prefix
• Updated metrics validation pattern in payloads.py from sglang_* to sglang:* to match actual format
• Verified fix with end-to-end aggregated deployment test showing correct sglang: metrics exposure
• Ensures consistency between code, documentation, and actual metrics output

Where should the reviewer start?

• components/src/dynamo/sglang/publisher.py - Review the removal of add_prefix parameter
• tests/utils/payloads.py - Review the updated validation pattern for SGLang metrics
• Documentation at fern/pages/backends/sglang/prometheus.md already correctly states metrics use sglang: prefix

Related Issues:

DYN-1962

/coderabbit profile chill

Summary by CodeRabbit

• Refactor

  • Simplified metrics prefix handling in registry configuration.

• Tests

  • Updated metrics validation pattern for backend verification to use colon-delimited naming format.

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[coderabbitai]

Walkthrough

Updates sglang metrics naming convention from underscore-based to colon-based delimiters. Removes explicit prefix configuration from publisher code and updates corresponding validation patterns in test utilities to match the new naming format.

Changes

Cohort / File(s)	Summary
Sglang Metrics Naming Updates components/src/dynamo/sglang/publisher.py, tests/utils/payloads.py	Transitions metric naming from underscore (sglang_*) to colon-based delimiters (sglang:*). Removes add_prefix argument from register_engine_metrics_callback, relying on default behavior. Updates regex patterns in metrics validation from ^sglang_\w+ to ^sglang:\w+ to match the new naming scheme.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 Hops through metrics with glee,
Colons replace underscores, so neat!
No prefix needed, defaults run free,
New naming scheme makes validation complete!

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately describes the main change: correcting the SGLang metrics prefix from underscore to colon format, which aligns with the actual code modifications.
Description check	✅ Passed	The description covers all required template sections with comprehensive details about the changes, rationale, files to review, and related issue reference.

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