docs: out_opentelemetry: Add 'encoding' option for OTLP/HTTP JSON export

[meehanman]

Documentation required for PR out_opentelemetry: Add 'encoding' option for OTLP/HTTP JSON export which adds an encoding configuration option to the out_opentelemetry plugin that controls whether OTLP data is exported as protobuf (default, existing behavior) or JSON (Content-Type: application/json) over HTTP.

While I was at it there are also included Clarifications & rewrites

• Adds a callout clarifying that encoding only applies to OTLP/HTTP (not gRPC), and that profiles always use protobuf regardless.
• Updated the intro to explicitly name OTLP/HTTP and OTLP/gRPC as the two transport options (replacing the vague "HTTP endpoint only" note).
• Rewrote grpc option description to remove the misleading auto value and clarify it enables HTTP/2 automatically.
• Improved descriptions across ~20 logs_* keys — replacing generic "Specify a X key" placeholders with accurate descriptions of whether the key reads from the record body vs. metadata.
• Clarified logs_body_key behaviour: multiple values allowed, first match wins, defaults to $log then $message.

Summary by CodeRabbit

• Documentation
  • Clarified OpenTelemetry output supports OTLP/HTTP and OTLP/gRPC, including HTTP/2 requirement for gRPC.
  • Documented support for logs, metrics, traces, and profiles and refreshed "Get started" guidance for all signal types.
  • Added an "Encoding" section (protobuf vs JSON; encoding applies to OTLP/HTTP only; profiles always protobuf).
  • Expanded configuration table with encoding, gRPC/http2 options; updated logs mapping keys, defaults, and examples.

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• pipeline/outputs/opentelemetry.md

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• pipeline/outputs/opentelemetry.md

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📝 Walkthrough

Walkthrough

This PR updates pipeline/outputs/opentelemetry.md to document OTLP over HTTP and gRPC (notes HTTP/2 requirement), expands configuration options (encoding, grpc, grpc_uri, http2, logs mappings), and refreshes the "Get started" section and full examples for logs, metrics, traces, and profiles.

Changes

OpenTelemetry Output Documentation

Layer / File(s)	Summary
Output description and configuration reference pipeline/outputs/opentelemetry.md	Plugin intro updated to state OTLP/HTTP and OTLP/gRPC support with HTTP/2 requirement for gRPC. Configuration table reworked to add encoding, grpc, grpc_*_uri, http2, and updated logs_* metadata/body mapping option descriptions and defaults; profiles_uri wording adjusted.
Get started guide and examples pipeline/outputs/opentelemetry.md	“Get started” rewritten to cover logs, metrics, traces, and profiles; added Encoding section explaining protobuf vs JSON and when encoding applies. Quickstart and Full examples updated (use encoding: json, adjusted fluent-bit.conf header and OTLP log mapping key casing, removed inline user-defined labels comment).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• fluent/fluent-bit-docs#2460: Also updates pipeline/outputs/opentelemetry.md with overlapping changes to gRPC and logs-related configuration keys.

Suggested labels

5.0

Suggested reviewers

• patrick-stephens
• alexakreizinger

Poem

🐰 I nibbled docs with floppy-ear delight,
OTLP paths set straight by morning light,
HTTP, gRPC, encodings in tune,
Examples tidy beneath the moon,
A rabbit cheers this doc-update flight.

🚥 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 directly describes the main change: addition of the 'encoding' option documentation for OTLP/HTTP JSON export, which is the primary focus of the PR.
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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[eschabell]

@meehanman thanks for the docs PR, just a few vale issues to address.

[coderabbitai]

Actionable comments posted: 1

🤖 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/outputs/opentelemetry.md`:
- Line 40: The description for logs_body_key is a sentence fragment; update the
paragraph for the `logs_body_key` entry so it is a complete sentence (e.g.,
"This option can be specified multiple times."). Edit the table row for
`logs_body_key` to replace "Can be specified multiple times." with a full
sentence while preserving the rest of the text and formatting, ensuring
consistency with other table entries.

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[coderabbitai]

Actionable comments posted: 1

🤖 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/outputs/opentelemetry.md`:
- Line 120: The sentence implying generic HTTP webhook compatibility is
misleading; update the line that mentions "encoding json" and "Content-Type:
application/json" to clarify that OTLP JSON is accepted only by OTLP/HTTP
receivers that explicitly support JSON encoding (not arbitrary webhooks).
Replace "such as HTTP webhook endpoints" with wording like "for OTLP/HTTP
receivers that explicitly support JSON encoding" and ensure the explanation
stays technical and neutral, referencing the "encoding json" option and the
resulting "Content-Type: application/json" header.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

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

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[eschabell]

@meehanman a simple vale issue.

[eschabell]

@meehanman I'd just replace the - with a comma to fix this issue, as that does not change the meaning?