http_server: document new ingress config and metrics

[edsiper]

documents changes from: fluent/fluent-bit#11704

This PR documents the new deferred ingress queue settings and metrics for HTTP-based inputs.

It adds the new shared HTTP listener settings:

• http_server.ingress_queue_event_limit
• http_server.ingress_queue_byte_limit

It also documents the new /api/v2/metrics/prometheus metrics:

• fluentbit_input_http_server_ingress_queue_pending_events
• fluentbit_input_http_server_ingress_queue_pending_bytes
• fluentbit_input_http_server_ingress_queue_busy_total

Scope

• Update the shared HTTP listener documentation in the YAML pipeline/service docs
• Update the v2 monitoring metrics reference
• Update the affected HTTP-based input pages:
  • http
  • splunk
  • elasticsearch
  • opentelemetry
  • prometheus_remote_write

Reader experience improvements

The plugin pages now make it explicit that their configuration tables include both:

• plugin-specific settings
• shared http_server.* listener settings

They also link back to the shared listener section so new users can understand which options are common across inputs and when the ingress queue settings apply.

Notes

The ingress queue settings and metrics apply only when http_server.workers > 1.

Summary by CodeRabbit

• Documentation
  • Introduced two new HTTP listener queue configuration parameters with defaults and applicability conditions for HTTP-based input plugins.
  • Enhanced documentation structure to distinguish shared HTTP listener settings from plugin-specific configuration.
  • Added three new metrics to monitor HTTP server queue status, pending events, and backpressure conditions.

[coderabbitai]

📝 Walkthrough

Walkthrough

Documentation updates across multiple Fluent Bit configuration files adding two new HTTP listener configuration keys (http_server.ingress_queue_event_limit and http_server.ingress_queue_byte_limit) and three new metrics for HTTP-based input plugins, with applicability conditioned on http_server.workers > 1.

Changes

Cohort / File(s)	Summary
Administration & Configuration Documentation administration/configuring-fluent-bit/yaml/pipeline-section.md, administration/configuring-fluent-bit/yaml/service-section.md, administration/monitoring.md	Added documentation for shared HTTP listener ingress queue configuration keys and related metrics. Clarified applicability conditions for http_server.ingress_queue_event_limit and http_server.ingress_queue_byte_limit when http_server.workers > 1. Introduced three new HTTP input metrics tracking ingress queue state.
Upgrade & Release Notes installation/upgrade-notes.md, installation/whats-new-in-fluent-bit-v5.0.md	Updated Fluent Bit v5.0 release documentation to include new http_server.ingress_queue_* configuration keys alongside existing shared HTTP listener settings.
Input Plugin Documentation pipeline/inputs/elasticsearch.md, pipeline/inputs/http.md, pipeline/inputs/opentelemetry.md, pipeline/inputs/prometheus-remote-write.md, pipeline/inputs/splunk.md	Added documentation for two new ingress queue configuration parameters with default values and worker-count conditions. Clarified distinction between plugin-specific and shared http_server.* listener settings across all HTTP-based input plugins.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related issues

• docs: inputs: several plugin docs need updating with HTTP listener workers details #2486: Directly extends HTTP listener workers and http_server.* canonicalization updates by documenting ingress queue limits dependent on worker count condition.

Possibly related PRs

• updates for v5.0 #2541: Establishes shared http_server.* listener documentation foundation that this PR builds upon by adding ingress queue configuration and metrics.
• Diverse input plugin docs are missing the http_server.workers parameter #2491: Introduces http_server.workers configuration, which this PR references as the condition for applying the new ingress queue limits.

Suggested labels

5.0

Suggested reviewers

• cosmo0920
• patrick-stephens
• eschabell

Poem

🐰 A queue of events, so nicely confined,
With limits by workers, so thoughtfully designed,
From Splunk to Elasticsearch, the docs now unfold,
Ingress queue limits—a story to be told! 📚

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title directly reflects the main change: documenting new HTTP ingress queue configuration settings and related Prometheus metrics for HTTP-based inputs.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch http_server_ingress

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[coderabbitai]

🧹 Nitpick comments (5)

pipeline/inputs/elasticsearch.md (1)

13-13: Consider alternative phrasing for "below".

Similar to other files in this PR, consider using "This table includes both:" instead of "The table below includes both:" to avoid directional language.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@pipeline/inputs/elasticsearch.md` at line 13, Replace the phrase "The table
below includes both:" with directional-neutral wording; locate the exact string
"The table below includes both:" in pipeline/inputs/elasticsearch.md and change
it to "This table includes both:" so phrasing matches other files and avoids
directional language.

pipeline/inputs/opentelemetry.md (1)

17-17: Consider alternative phrasing for "below".

To maintain consistency with style guidelines and improve accessibility, consider "This table includes both:" instead of "The table below includes both:".

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@pipeline/inputs/opentelemetry.md` at line 17, Replace the phrase "The table
below includes both:" with "This table includes both:" in the opentelemetry.md
content so wording is consistent with style guidelines and improves
accessibility; search for the exact string "The table below includes both:" and
update it to the suggested alternative.

pipeline/inputs/prometheus-remote-write.md (1)

15-15: Consider alternative phrasing for "below".

The static analysis tool flags the use of "below" as directional language. While this is a minor style issue, consider alternatives like "The following table includes both:" or simply "This table includes both:" for improved accessibility and clarity.

✏️ Suggested alternative phrasing

-The table below includes both:
+This table includes both:

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@pipeline/inputs/prometheus-remote-write.md` at line 15, Replace the
directional phrasing "The table below includes both:" with a non-directional
alternative to improve accessibility—e.g., change the sentence to "The following
table includes both:" or "This table includes both:" in the content where the
string "The table below includes both:" appears so the copy no longer relies on
spatial language.

pipeline/inputs/splunk.md (1)

13-13: Consider alternative phrasing for "below".

For consistency with style guidelines, consider "This table includes both:" instead of "The table below includes both:".

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@pipeline/inputs/splunk.md` at line 13, Replace the phrase "The table below
includes both:" with the preferred phrasing "This table includes both:" — locate
the sentence containing the exact string "The table below includes both:" in
pipeline/inputs/splunk.md and update it to "This table includes both:" to match
style guidelines.

pipeline/inputs/http.md (1)

12-12: Consider alternative phrasing for "below".

To align with style guidelines and improve accessibility, consider "This table includes both:" instead of "The table below includes both:".

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@pipeline/inputs/http.md` at line 12, Replace the wording "The table below
includes both:" with "This table includes both:" in the Markdown content where
that sentence appears (update the specific line that currently reads "The table
below includes both:" to the new phrasing and adjust any other identical
occurrences to match the style guideline).

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@pipeline/inputs/elasticsearch.md`:
- Line 13: Replace the phrase "The table below includes both:" with
directional-neutral wording; locate the exact string "The table below includes
both:" in pipeline/inputs/elasticsearch.md and change it to "This table includes
both:" so phrasing matches other files and avoids directional language.

In `@pipeline/inputs/http.md`:
- Line 12: Replace the wording "The table below includes both:" with "This table
includes both:" in the Markdown content where that sentence appears (update the
specific line that currently reads "The table below includes both:" to the new
phrasing and adjust any other identical occurrences to match the style
guideline).

In `@pipeline/inputs/opentelemetry.md`:
- Line 17: Replace the phrase "The table below includes both:" with "This table
includes both:" in the opentelemetry.md content so wording is consistent with
style guidelines and improves accessibility; search for the exact string "The
table below includes both:" and update it to the suggested alternative.

In `@pipeline/inputs/prometheus-remote-write.md`:
- Line 15: Replace the directional phrasing "The table below includes both:"
with a non-directional alternative to improve accessibility—e.g., change the
sentence to "The following table includes both:" or "This table includes both:"
in the content where the string "The table below includes both:" appears so the
copy no longer relies on spatial language.

In `@pipeline/inputs/splunk.md`:
- Line 13: Replace the phrase "The table below includes both:" with the
preferred phrasing "This table includes both:" — locate the sentence containing
the exact string "The table below includes both:" in pipeline/inputs/splunk.md
and update it to "This table includes both:" to match style guidelines.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 78428e65-d9cc-4ad7-af4a-3843aa968a36

📥 Commits

Reviewing files that changed from the base of the PR and between 67f97c7 and bab3b18.

📒 Files selected for processing (10)

• administration/configuring-fluent-bit/yaml/pipeline-section.md
• administration/configuring-fluent-bit/yaml/service-section.md
• administration/monitoring.md
• installation/upgrade-notes.md
• installation/whats-new-in-fluent-bit-v5.0.md
• pipeline/inputs/elasticsearch.md
• pipeline/inputs/http.md
• pipeline/inputs/opentelemetry.md
• pipeline/inputs/prometheus-remote-write.md
• pipeline/inputs/splunk.md