Added section to router docs for label-based matching for Fluent Bit 4.2. Fixes #2203.

[eschabell]

Added section to router docs for label-based matching for Fluent Bit 4.2. Fixes #2203.

Summary by CodeRabbit

Release Notes

• Documentation
  • Added comprehensive guide for label-based routing with configuration examples and best practices
  • Documented label storage mechanism and matching process for stable routing
  • Updated routing strategy guidance presenting three approaches: tag-based, conditional, and label-based matching
  • Included production and development routing scenarios

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[coderabbitai]

Walkthrough

The router.md documentation file is updated to introduce a new "Label-based Matching" section explaining how labels and plugin names stored in chunk metadata enable stable, direct routing across configuration changes and restarts, with configuration examples and best practices.

Changes

Cohort / File(s)	Summary
Documentation - Label-based Routing pipeline/router.md	Adds new "Label-based Matching" section covering label storage, matching order (aliases, generated names, ID fallback), benefits, configuration guidance, examples (fluent-bit.yaml and fluent-bit.conf), route restoration behavior, plugin-name matching, best practices, and updates routing approach decision table to include label-based matching alongside tag-based and conditional routing.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

• Content focus: Documentation clarity and accuracy of label-based matching concepts
• Examples: Configuration snippets (fluent-bit.yaml and fluent-bit.conf) should be validated for syntax correctness
• Consistency: Ensure decision table accurately reflects the three routing approaches and their use cases

Poem

🐰 With labels as our trusty guides,
Through restarts and changes we ride,
Names and aliases, stable and true,
Chunks find their home, always on cue!
Label-based routing—the hopper's delight! 🎯

Pre-merge checks and finishing touches

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: adding documentation for label-based matching to the router docs, with a specific reference to the issue it addresses.
Linked Issues check	✅ Passed	All objectives from issue #2203 are met: label-based matching is documented as a new section with comprehensive examples showing how to match routes using labels and plugin names in chunk metadata.
Out of Scope Changes check	✅ Passed	All changes focus solely on documenting label-based matching in the router documentation, with no unrelated modifications or scope creep detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

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[coderabbitai]

Actionable comments posted: 1

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 659d629 and 754e31e.

📒 Files selected for processing (1)

• pipeline/router.md (3 hunks)

🧰 Additional context used

🪛 GitHub Actions: Lint PRs

pipeline/router.md

[error] 770-770: FluentBit.Latin: Use 'through or by using' instead of ' via '.

🪛 GitHub Check: runner / vale

pipeline/router.md

[failure] 770-770:
[vale] reported by reviewdog 🐶
[FluentBit.Latin] Use 'through or by using' instead of ' via '.

Raw Output:
{"message": "[FluentBit.Latin] Use 'through or by using' instead of ' via '.", "location": {"path": "pipeline/router.md", "range": {"start": {"line": 770, "column": 47}}}, "severity": "ERROR"}

🔇 Additional comments (2)

pipeline/router.md (2)

7-11: Intro updates correctly establish three routing approaches.

The updated introduction and bullet list clearly establish label-based matching as a distinct approach alongside tag-based and conditional routing, setting up the new documentation section logically.

---

757-948: New Label-based Matching section is well-structured and addresses all PR objectives.

The section comprehensively covers:

• Clear explanation of how labels and plugin names enable stable routing
• Configuration examples in both YAML and classic syntax
• Benefits of the approach with concrete reasons (configuration resilience, stable restarts, type safety)
• Matching logic walkthrough (alias → generated name → ID fallback)
• Practical example demonstrating production/development routing with aliases
• Best practices subsection with actionable guidance

Documentation is thorough, examples are clear, and the integration with the updated decision table (lines 935–946) appropriately positions label-based matching alongside existing approaches.

[eschabell]

AI review passed, merging.