docs: pipeline: outputs: opentelemetry: document gRPC support

[edsiper]

Summary

• document OTLP/HTTP and OTLP/gRPC transport support
• explain gRPC's automatic HTTP/2 and h2c configuration
• add default signal URI mappings and gRPC configuration examples
• correct the grpc, http2, compression, and logs_body_key parameter descriptions

Why

The OpenTelemetry output documentation said that only HTTP endpoints were supported even though the plugin implements OTLP/gRPC. It also described grpc as supporting an auto value, while the implementation defines it as a boolean setting.

This addresses the documentation portion of fluent/fluent-bit#10821. It doesn't attempt to resolve or close the separately reported high-rate delivery behavior.

User impact

Users can now configure OTLP/gRPC without also setting http2, distinguish OTLP/HTTP over HTTP/2 from gRPC, and select the correct signal-specific endpoint paths.

Validation

• git diff --check
• verified balanced GitBook tab and code-fence directives

Summary by CodeRabbit

• Documentation
  • Clarified OpenTelemetry transport behavior, including OTLP/HTTP defaults and OTLP/gRPC configuration.
  • Documented default per-signal endpoints for logs, metrics, traces, and profiles.
  • Expanded configuration reference details for compression, headers, hosts, HTTP/2, logging options, and signal-specific URIs.
  • Updated parameter descriptions and introductory examples to accurately reflect supported exports and OTLP server behavior.

[coderabbitai]

Caution

Review failed

The pull request is closed.

ℹ️ Recent review info

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Configuration used: defaults

Review profile: CHILL

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Run ID: 7d4c1a6a-f1cc-451a-8bb0-88b144419fb6

📥 Commits

Reviewing files that changed from the base of the PR and between a391227 and 4283642.

📒 Files selected for processing (1)

• pipeline/outputs/opentelemetry.md

---

📝 Walkthrough

Walkthrough

The OpenTelemetry output documentation now explains OTLP transport modes, defaults, URI mappings, configuration parameters, log body selection, and an OTLP/HTTP-over-TLS example.

Changes

OpenTelemetry documentation

Layer / File(s)	Summary
Transport and configuration semantics pipeline/outputs/opentelemetry.md	Documents OTLP/HTTP and OTLP/gRPC behavior, HTTP/2 handling, per-signal URI defaults, compression, headers, host settings, logging controls, and log body selection.
OTLP endpoint and example updates pipeline/outputs/opentelemetry.md	Updates the port description for OTLP servers and revises the example to cover logs, host metrics, and traces over OTLP/HTTP with TLS.

Estimated code review effort: 1 (Trivial) | ~3 minutes

Possibly related PRs

• fluent/fluent-bit-docs#2460: Updates overlapping OpenTelemetry configuration documentation, including grpc and logs_body_key.

Suggested labels: 5.0

Suggested reviewers: alexakreizinger, patrick-stephens

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/opentelemetry-grpc-10821

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[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe is missing space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe is missing space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe is missing space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe is missing space to the right for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe is missing space to the right for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe has extra space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe has extra space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe has extra space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe has extra space to the left for style "compact"]

[github-actions]

[markdownlint] _{reported by reviewdog 🐶}
error MD060/table-column-style Table column style [Table pipe has extra space to the left for style "compact"]

[github-actions]

[markdownlint-fix] _{reported by reviewdog 🐶}

Suggested change

	|---|---|---|
	| --- | --- | --- |

[github-actions]

[markdownlint-fix] _{reported by reviewdog 🐶}

fluent-bit-docs/pipeline/outputs/opentelemetry.md

Lines 60 to 160 in 4283642

	| Key | Description | Default |
	|---------|--------------|---------|
	| `add_label` | Adds a custom label to the metrics use format: `add_label name value`. | _none_ |
	| `alias` | Sets an alias, use for multiple instances of the same output plugin. | _none_ |
	| `aws_auth` | Enable AWS SigV4 authentication. | `false`|
	| `aws_external_id` | Specify an external ID for the STS API, can be used with the `aws_role_arn` parameter. | _none_ |
	| `aws_profile` | AWS Profile name. AWS Profiles can be configured with AWS CLI. | _none_ |
	| `aws_region` | AWS region of your service. | _none_ |
	| `aws_role_arn` | ARN of an IAM role to assume (ex. for cross account access). | _none_ |
	| `aws_service` | AWS destination service code, used by SigV4 authentication. | `logs` |
	| `aws_sts_endpoint` | Custom endpoint for the AWS STS API, used with the `aws_role_arn` option. | _none_ |
	| `batch_size` | Set the maximum number of log records to be flushed at a time. | `1000` |
	| `compress` | Set the OTLP/HTTP payload compression mechanism. Available options are `gzip` and `zstd`. | _none_ |
	| `grpc` | Use OTLP/gRPC over HTTP/2. Accepted values are `on` and `off`. Enabling this option also enables HTTP/2. | `off` |
	| `grpc_logs_uri` | Set the gRPC method path for log exports. | `/opentelemetry.proto.collector.logs.v1.LogsService/Export` |
	| `grpc_metrics_uri` | Set the gRPC method path for metric exports. | `/opentelemetry.proto.collector.metrics.v1.MetricsService/Export` |
	| `grpc_profiles_uri` | Set the gRPC method path for profile exports. | `/opentelemetry.proto.collector.profiles.v1experimental.ProfilesService/Export` |
	| `grpc_traces_uri` | Set the gRPC method path for trace exports. | `/opentelemetry.proto.collector.trace.v1.TraceService/Export` |
	| `header` | Add a HTTP header key/value pair. Multiple headers can be set. | _none_ |
	| `host` | IP address or hostname of the target OTLP server. | `127.0.0.1` |
	| `http2` | Control HTTP/2 independently of `grpc`. Accepted values are `on`, `off`, and `force`. With TLS, `on` negotiates the protocol and `force` requires HTTP/2. You don't need to set this when `grpc` is `on`. | `off` |
	| `http_passwd` | Set HTTP auth password. | _none_ |
	| `http_user` | Set HTTP auth user. | _none_ |
	| `log_level` | Specifies the log level for output plugin. If not set here, plugin uses global log level in `service` section. | `info` |
	| `log_response_payload` | Specify if the response payload should be logged or not. | `true` |
	| `log_suppress_interval` | Suppresses log messages from output plugin that appear similar within a specified time interval. `0` disables suppression. | `0` |
	| `logs_attributes_metadata_key` | Specify an `Attributes` key. | `$Attributes` |
	| `logs_body_key` | Set a record accessor that selects the value to use as the OTLP log body. | _none_ |
	| `logs_body_key_attributes` | If set and it matched a pattern, it includes the remaining fields in the record as attributes. | `false`|
	| `logs_instrumentation_scope_metadata_key` | Specify an `InstrumentationScope` key. | `InstrumentationScope` |
	| `logs_max_resources` | Set the maximum number of OTLP log resources per export request (`0` disables the limit). | `0` |
	| `logs_max_scopes` | Set the maximum number of OTLP log scopes per resource (`0` disables the limit). | `0` |
	| `logs_metadata_key` | Set the key to look up in the metadata. | `otlp` |
	| `logs_observed_timestamp_metadata_key` | Specify an `ObservedTimestamp` key. | `$ObservedTimestamp` |
	| `logs_resource_metadata_key` | Specify a `Resource` key. | `Resource` |
	| `logs_severity_number_message_key` | Specify a `SeverityNumber` key. | `$severityNumber` |
	| `logs_severity_number_metadata_key` | Specify a `SeverityNumber` key. | `$SeverityNumber` |
	| `logs_severity_text_message_key` | Specify a `SeverityText` key. | `$SeverityText` |
	| `logs_severity_text_metadata_key` | Specify a `SeverityText` key. | `$SeverityText` |
	| `logs_span_id_message_key` | Specify a `SpanId` key. | `$SpanId` |
	| `logs_span_id_metadata_key` | Specify a `SpanId` key. | `$SpanId` |
	| `logs_timestamp_metadata_key` | Specify a `Timestamp` key. | `$Timestamp` |
	| `logs_trace_flags_metadata_key` | Specify a `TraceFlags` key. | `$TraceFlags` |
	| `logs_trace_id_message_key` | Specify a `TraceId` key. | `$TraceId` |
	| `logs_trace_id_metadata_key` | Specify a `TraceId` key. | `$TraceId` |
	| `logs_uri` | Specify an optional HTTP URI for the target OTel endpoint. | `/v1/logs` |
	| `match` | Set a tag pattern to match records that output should process. Exact matches or wildcards (for example `*`). | _none_ |
	| `match_regex` | Set a regular expression to match tags for output routing. This allows more flexible matching compared to wildcards. | _none_ |
	| `metrics_uri` | Specify an optional HTTP URI for the target OTel endpoint. | `/v1/metrics` |
	| `net.connect_timeout` | Set maximum time allowed to establish a connection, this time includes the TLS handshake. | `10s` |
	| `net.connect_timeout_log_error` | On connection timeout, specify if it should log an error. When disabled, the timeout is logged as a debug message. | `true` |
	| `net.dns.mode` | Select the primary DNS connection type (TCP or UDP). | _none_ |
	| `net.dns.prefer_ipv4` | Select the primary DNS resolver type (LEGACY or ASYNC). | _none_ |
	| `net.dns.prefer_ipv6` | Prioritize IPv6 DNS results when trying to establish a connection. | _none_ |
	| `net.io_timeout` | Set maximum time a connection can stay idle while assigned. | `0s` |
	| `net.keepalive_max_recycle` | Set maximum number of times a keepalive connection can be used before it retries. | `2000` |
	| `net.max_worker_connections` | Set the maximum number of active TCP connections that can be used per worker thread. | `0` |
	| `net.proxy_env_ignore` | Ignore the environment variables `HTTP_PROXY`, `HTTPS_PROXY` and `NO_PROXY` when set. | `false`|
	| `net.source_address` | Specify network address to bind for data traffic. | _none_ |
	| `net.tcp_keepalive` | Enable or disable Keepalive support. | `off` |
	| `net.tcp_keepalive_interval` | Interval between TCP keepalive probes when no response is received on a `keepidle` probe. | `-1` |
	| `net.tcp_keepalive_probes` | Number of unacknowledged probes to consider a connection dead. | `-1` |
	| `net.tcp_keepalive_time` | Interval between the last data packet sent and the first TCP keepalive probe. | `-1` |
	| `oauth2.audience` | Optional `OAuth 2.0` audience parameter. | _none_ |
	| `oauth2.auth_method` | `OAuth 2.0` client authentication method. Supported values: `basic`, `post`, `private_key_jwt`. | `basic` |
	| `oauth2.client_id` | `OAuth 2.0` client ID. | _none_ |
	| `oauth2.client_secret` | `OAuth 2.0` client secret. | _none_ |
	| `oauth2.connect_timeout` | Connect timeout for `OAuth 2.0` token requests. | `0s` |
	| `oauth2.enable` | Enable `OAuth 2.0` client credentials for outgoing requests. | `false`|
	| `oauth2.jwt_aud` | Audience for `private_key_jwt` JSON Web Token (JWT) assertion. Defaults to the value of `oauth2.token_url` when not set. | _none_ |
	| `oauth2.jwt_cert_file` | Path to certificate file used by `private_key_jwt`. | _none_ |
	| `oauth2.jwt_header` | JWT header claim name for `private_key_jwt` thumbprint. Accepted values: `kid`, `x5t`. | `kid` |
	| `oauth2.jwt_key_file` | Path to PEM private key file used by `private_key_jwt`. | _none_ |
	| `oauth2.jwt_ttl_seconds` | Lifetime in seconds for `private_key_jwt` JWT client assertions. | `300` |
	| `oauth2.refresh_skew_seconds` | Seconds before expiry at which to refresh the access token. | `60` |
	| `oauth2.resource` | Optional `OAuth 2.0` resource parameter. | _none_ |
	| `oauth2.scope` | Optional `OAuth 2.0` scope. | _none_ |
	| `oauth2.timeout` | Timeout for `OAuth 2.0` token requests. | `0s` |
	| `oauth2.token_url` | `OAuth 2.0` token endpoint URL. | _none_ |
	| `oauth2.user_agent` | Optional `User-Agent` header value to include in `OAuth 2.0` token requests. If omitted, no `User-Agent` header is sent. | _none_ |
	| `port` | TCP port of the target OTLP server. | `80` |
	| `profiles_uri` | Specify an optional HTTP URI for the profiles OTel endpoint. | `/v1development/profiles` |
	| `proxy` | Specify an HTTP Proxy. The expected format of this value is `http://host:port`.| _none_ |
	| `retry_limit` | Set retry limit for output plugin when delivery fails. Integer, `no_limits`, `false`, or `off` to disable, or `no_retries` to disable retries entirely. | `1` |
	| `tls` | Enable or disable TLS/SSL support. | `off` |
	| `tls.ca_file` | Absolute path to CA certificate file. | _none_ |
	| `tls.ca_path` | Absolute path to scan for certificate files. | _none_ |
	| `tls.ciphers` | Specify TLS ciphers up to TLSv1.2. | _none_ |
	| `tls.crt_file` | Absolute path to Certificate file. | _none_ |
	| `tls.debug` | Set TLS debug level. Accepts `0` (No debug), `1`(Error), `2` (State change), `3` (Informational) and `4` (Verbose). | `1` |
	| `tls.key_file` | Absolute path to private Key file. | _none_ |
	| `tls.key_passwd` | Optional password for tls.key_file. | _none_ |
	| `tls.max_version` | Specify the maximum version of TLS. | _none_ |
	| `tls.min_version` | Specify the minimum version of TLS. | _none_ |
	| `tls.verify` | Force certificate validation. | `on` |
	| `tls.verify_hostname` | Enable or disable to verify hostname. | `off` |
	| `tls.vhost` | Hostname to be used for TLS SNI extension. | _none_ |
	| `tls.windows.certstore_name` | Sets the `certstore` name on an output (Windows). | _none_ |
	| `tls.windows.use_enterprise_store` | Sets whether using enterprise `certstore` or not on an output (Windows). | _none_ |
	| `traces_uri` | Specify an optional HTTP URI for the target OTel endpoint. | `/v1/traces` |
	| `workers` | The number of [workers](../../administration/multithreading.md#outputs) to perform flush operations for this output. | `0` |