Adapters

OTLP Adapter

Send logs via OpenTelemetry Protocol (OTLP) to Grafana, Datadog, Honeycomb, and any compatible backend. Supports gRPC and HTTP transports.

The OTLP (OpenTelemetry Protocol) adapter sends logs in the standard OpenTelemetry format. This works with any OTLP-compatible backend including:

Grafana Cloud (Loki)
Datadog
Honeycomb
Jaeger
Splunk
New Relic
Self-hosted OpenTelemetry Collector

Installation

The OTLP adapter comes bundled with evlog:

server/plugins/evlog-drain.ts

import { createOTLPDrain } from 'evlog/otlp'

Quick Start

1. Set your OTLP endpoint

.env

NUXT_OTLP_ENDPOINT=http://localhost:4318

2. Create the drain plugin

server/plugins/evlog-drain.ts

import { createOTLPDrain } from 'evlog/otlp'

export default defineNitroPlugin((nitroApp) => {
  nitroApp.hooks.hook('evlog:drain', createOTLPDrain())
})

Configuration

The adapter reads configuration from multiple sources (highest priority first):

Overrides passed to createOTLPDrain()
Runtime config at runtimeConfig.evlog.otlp
Runtime config at runtimeConfig.otlp
Environment variables (NUXT_OTLP_* or OTEL_*)

Environment Variables

Variable	Description
`NUXT_OTLP_ENDPOINT`	OTLP HTTP endpoint (e.g., `http://localhost:4318`)
`NUXT_OTLP_SERVICE_NAME`	Override service name
`NUXT_OTLP_HEADERS`	Custom headers (format: `Key=Value,Key2=Value2`)
`NUXT_OTLP_AUTH`	Shortcut for `Authorization` header

Standard OpenTelemetry variables are also supported:

Variable	Description
`OTEL_EXPORTER_OTLP_ENDPOINT`	OTLP endpoint (fallback)
`OTEL_EXPORTER_OTLP_HEADERS`	Headers in OTEL format
`OTEL_SERVICE_NAME`	Service name (fallback)

Runtime Config

nuxt.config.ts

export default defineNuxtConfig({
  runtimeConfig: {
    otlp: {
      endpoint: '', // Set via NUXT_OTLP_ENDPOINT
    },
  },
})

Override Options

server/plugins/evlog-drain.ts

import { createOTLPDrain } from 'evlog/otlp'

export default defineNitroPlugin((nitroApp) => {
  nitroApp.hooks.hook('evlog:drain', createOTLPDrain({
    endpoint: 'http://localhost:4318',
    serviceName: 'my-api',
    headers: {
      'Authorization': 'Bearer xxx',
    },
    resourceAttributes: {
      'deployment.environment': 'staging',
    },
  }))
})

Full Configuration Reference

Option	Type	Default	Description
`endpoint`	`string`	-	OTLP HTTP endpoint (required)
`serviceName`	`string`	From event	Override `service.name` resource attribute
`headers`	`object`	-	Custom HTTP headers for authentication
`resourceAttributes`	`object`	-	Additional OTLP resource attributes
`timeout`	`number`	`5000`	Request timeout in milliseconds

Provider-Specific Setup

Grafana Cloud

Go to your Grafana Cloud portal
Navigate to Connections > Collector > OpenTelemetry
Copy your OTLP endpoint and generate credentials

.env

NUXT_OTLP_ENDPOINT=https://otlp-gateway-prod-us-central-0.grafana.net/otlp
OTEL_EXPORTER_OTLP_HEADERS=Authorization=Basic%20base64-encoded-credentials

Grafana uses URL-encoded headers. The %20 is a space character. The adapter automatically decodes this format.

Datadog

.env

NUXT_OTLP_ENDPOINT=https://http-intake.logs.datadoghq.com
NUXT_OTLP_HEADERS=DD-API-KEY=your-api-key

Local OpenTelemetry Collector

For development and testing, run a local collector:

otel-collector.yaml

receivers:
  otlp:
    protocols:
      http:
        endpoint: 0.0.0.0:4318

exporters:
  debug:
    verbosity: detailed

service:
  pipelines:
    logs:
      receivers: [otlp]
      exporters: [debug]

docker run --rm -p 4318:4318 \
  -v $(pwd)/otel-collector.yaml:/etc/otelcol/config.yaml \
  otel/opentelemetry-collector:latest

.env

NUXT_OTLP_ENDPOINT=http://localhost:4318

OTLP Log Format

evlog maps wide events to the OTLP log format:

evlog Field	OTLP Field
`level`	`severityNumber` / `severityText`
`timestamp`	`timeUnixNano`
`service`	Resource attribute `service.name`
`environment`	Resource attribute `deployment.environment`
`version`	Resource attribute `service.version`
`region`	Resource attribute `cloud.region`
`traceId`	`traceId`
`spanId`	`spanId`
All other fields	Log attributes

Severity Mapping

evlog Level	OTLP Severity Number	OTLP Severity Text
`debug`	5	DEBUG
`info`	9	INFO
`warn`	13	WARN
`error`	17	ERROR

Troubleshooting

Missing endpoint error

[evlog/otlp] Missing endpoint. Set NUXT_OTLP_ENDPOINT or OTEL_EXPORTER_OTLP_ENDPOINT

Make sure your endpoint environment variable is set and the server was restarted.

401 Unauthorized

Your authentication headers may be missing or incorrect. Check:

The OTEL_EXPORTER_OTLP_HEADERS format is correct
Credentials are valid and not expired
The endpoint URL is correct

404 Not Found

The adapter sends to /v1/logs. Make sure your endpoint:

Supports OTLP HTTP (not gRPC)
Is the base URL without /v1/logs suffix

Logs not appearing

Check the server console for [evlog/otlp] error messages
Test with a local collector first to verify the format
Check your backend's ingestion delay (some have 1-2 minute delays)

Direct API Usage

For advanced use cases:

server/utils/otlp.ts

import { sendToOTLP, sendBatchToOTLP, toOTLPLogRecord } from 'evlog/otlp'

// Send a single event
await sendToOTLP(event, {
  endpoint: 'http://localhost:4318',
})

// Send multiple events
await sendBatchToOTLP(events, {
  endpoint: 'http://localhost:4318',
})

// Convert event to OTLP format (for inspection)
const otlpRecord = toOTLPLogRecord(event)

Next Steps

Axiom Adapter - Send logs to Axiom
PostHog Adapter - Send logs to PostHog
Custom Adapters - Build your own adapter
Best Practices - Security and production tips

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Axiom

Send wide events to Axiom for powerful querying, dashboards, and alerting. Zero-config setup with environment variables and automatic batching.

PostHog

Send wide events to PostHog as custom events for product analytics, session replay correlation, and structured log querying in your dashboards.