filter_logs_to_metrics: document field_value usage for counters

[databus23]

This documents a feature added with this PR: fluent/fluent-bit#10055

Summary by CodeRabbit

• Documentation
  • Added a new derived counter metric, "total_duration", sourced from the duration field and documented with a description.
  • Updated Prometheus sample output to include the new metric and adjusted sample values for existing counter examples.

[alexakreizinger]

hi @databus23, thanks for submitting a docs PR! I just suggested a few edits for clarity and consistency.

[databus23]

@alexakreizinger thanks for the feedback. I merged in all your suggestions.

[alexakreizinger]

awesome, thank you :) I'm approving this, but I won't merge anything since it sounds like we're still waiting on a different code PR—feel free to merge this one when the time comes.

[eschabell]

@databus23 can you resolve the conflicts please as I've also nudged the review on code PR fluent/fluent-bit#10055, so I can merge this when it's ready?

[esmerel]

The conflicts were due to formatting changes for style, I went ahead and fixed the conflicts in the interest of keeping things moving.

[coderabbitai]

Caution

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📝 Walkthrough

Walkthrough

Documentation for the Fluent Bit log_to_metrics filter is updated: the Counter example now defines a second counter metric total_duration (using value_field: duration), the fluent-bit example snippets add the Value_Field duration directive, and the Prometheus /metrics sample output reflects the new metric and adjusted values.

Changes

log_to_metrics Counter Example

Layer / File(s)	Summary
Counter metric example with total_duration metric pipeline/filters/log_to_metrics.md	Fluent Bit config examples extended to add a total_duration counter metric with metric_name, metric_description, and value_field: duration. Example fluent-bit.conf snippet adds Value_Field duration. The Prometheus /metrics example includes the new log_metric_counter_total_duration metric and adjusted sample values for the existing counter.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

I’m a rabbit in the logs, I hop and tally through the night,
Two counters now I nibble on, one sums duration’s flight,
Prometheus peeks and writes the totals in a row,
Docs now whisper how to count the time that logs bestow,
Hop, update, publish—metrics bloom in gentle light.

🚥 Pre-merge checks | ✅ 5

✅ 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 accurately describes the main change: documenting field_value usage for counters in the filter_logs_to_metrics component, which aligns with the PR's objective to document a feature from fluent-bit PR #10055.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[coderabbitai]

Actionable comments posted: 1

♻️ Duplicate comments (1)

pipeline/filters/log_to_metrics.md (1)

155-155: ⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Fix typo in metric HELP text.

time spend should be time spent to match the configured description and avoid confusion.

Suggested fix

-# HELP log_metric_counter_total_duration This metric counts the total time spend
+# HELP log_metric_counter_total_duration This metric counts the total time spent

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@pipeline/filters/log_to_metrics.md` at line 155, Update the HELP text for the
Prometheus metric named log_metric_counter_total_duration to correct the typo
"time spend" → "time spent" (edit the HELP line in
pipeline/filters/log_to_metrics.md so the description matches the configured
description and reads "This metric counts the total time spent").

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@pipeline/filters/log_to_metrics.md`:
- Around line 110-117: The YAML/classic examples are out of sync: add the same
counter configuration shown in the fluent-bit.conf example to the
fluent-bit.yaml/classic example so outputs match; specifically ensure the filter
named log_to_metrics includes metric_mode: counter, metric_name: total_duration,
metric_description and value_field: duration (mirror the total_duration counter
definition present in the conf example) so the sample output lines that show
both counters are reproducible.

---

Duplicate comments:
In `@pipeline/filters/log_to_metrics.md`:
- Line 155: Update the HELP text for the Prometheus metric named
log_metric_counter_total_duration to correct the typo "time spend" → "time
spent" (edit the HELP line in pipeline/filters/log_to_metrics.md so the
description matches the configured description and reads "This metric counts the
total time spent").

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: a696f61e-a519-4fa9-b060-95895dacadbc

📥 Commits

Reviewing files that changed from the base of the PR and between cab5957 and 15ea4a6.

📒 Files selected for processing (1)

• pipeline/filters/log_to_metrics.md

[coderabbitai]

Actionable comments posted: 0

[eschabell]

@databus23 waiting now on code PR merging.