trace0-lambda-otel-logger 1.0.4

OpenTelemetry-based logger for AWS Lambda Python functions

trace0-lambda-otel-logger

OpenTelemetry-based logger for AWS Lambda Python functions.

Automatically captures all logging output, injects OTel trace context (traceId, spanId), and exports logs as OTLP JSON to the Trace0 ingest endpoint.

See the Background section for more details on why this library is needed.

How it works

logging.info() 
  → Trace0LogHandler (logging.Handler bridge)
    → BatchLogProcessor (buffers during invocation)
      → OTLPJsonLogExporter (POST to Trace0 ingest endpoint)

Based on the OpenTelemetry Logs API specification.

Installation

pip install trace0-lambda-otel-logger

Usage

1. Add as the first import in your Lambda handler module:

import trace0_lambda_otel_logger  # must be first
from trace0_lambda_otel_logger import flush

2. Call flush() at the end of every invocation:

import logging

logger = logging.getLogger(__name__)

def handler(event, context):
    try:
        return your_handler(event, context)
    finally:
        flush()  # always flush before Lambda freezes

3. Set environment variables:

OTEL_EXPORTER_OTLP_ENDPOINT=https://app.trace0hq.com/api
OTEL_EXPORTER_OTLP_HEADERS=X-API-KEY=YOUR_TRACE0_ENV_API_KEY

That's it. No changes to your existing logging calls required.

Environment Variables

Variable	Required	Default	Description
OTEL_EXPORTER_OTLP_ENDPOINT	Yes	—	Your Trace0 ingest endpoint
OTEL_EXPORTER_OTLP_HEADERS	Yes	—	Your Trace0 API key

Log Record Format

Each log record is exported as OTLP JSON with the following fields:

{
  "timeUnixNano": "1234567890000000000",
  "severityNumber": 9,
  "severityText": "INFO",
  "body": { "stringValue": "User created" },
  "attributes": [
    { "key": "logger.name", "value": { "stringValue": "app.users" } },
    { "key": "code.function", "value": { "stringValue": "create_user" } },
    { "key": "code.lineno", "value": { "intValue": 42 } }
  ],
  "traceId": "abc123...",
  "spanId": "def456..."
}

Requirements

• Python >= 3.11
• AWS Lambda with the OpenTelemetry Lambda Layer attached (for trace context)

Background

To correlate logs with traces in Trace0, this library must be installed in your Lambda function. This is necessary because the OpenTelemetry Python Logs SDK is currently in an experimental state. The APIs within opentelemetry.sdk._logs are subject to change in minor/patch releases and make no backward compatibility guarantees at this time.

trace0-lambda-otel-logger solves this gap by installing a logging.Handler on the root logger that automatically injects the active OTel span's traceId and spanId into every log record, and exporting them directly to the Trace0 ingest endpoint. This enables full log-trace correlation with minimal integration effort.