Middy Pino Logging Middleware

Integrates the pino logging library with Middy.

Features include:

• Cloudwatch log formatting via pino-lambda
• Captures tracking ids in each log, including request ID and xray tracing ID
• Enables debug log sampling via debugRate option, or MIDDY_PINO_DEBUG_RATE environment variable
• Adds the logger to the request context, under context.log by default

Refer to the documentation for Pino for configuration and usage of the logger.

Refer to the documentation for Pino Lambda for additional configuration of log formatting.

Example Usage

Adding the Middleware

import middy from '@middy/core';
import createLoggingMiddleware from "middy-pino" ;

const handler = middy()
    .use(createLoggingMiddleware({ name: 'my-service-name' }))
    .handler(async (event, context) => {
        context.log.info('handling event');
    });

Bring Your Own Pino

import middy from '@middy/core';
import pino from 'pino';
import { pinoLambdaDestination } from 'pino-lambda';
import createLoggingMiddleware from "middy-pino" ;

// you must still use pino-lambda destination
const logger = pino({ name: 'my-service-name' }, pinoLambdaDestination())

const handler = middy()
    .use(createLoggingMiddleware({ logger }))
    .handler(async (event, context) => {
        context.log.info('handling event');
    });

Sharing Logger Outside Handler

// logger.js
import { createLogger } from "middy-pino" ;

export default createLogger({ name: 'my-service-name' });

// someModule.js
import logger from './logger.js'

export functionDoSomething() {
    logger.info('doing something outside handler')
}

// index.js
import middy from '@middy/core';
import createLoggingMiddleware from "middy-pino";
import logger from './logger.js';

const handler = middy()
    .use(createLoggingMiddleware({ logger }))
    .handler(async (event, context) => {
        context.log.info('handling event');
    });

Track Additional Fields

import middy from '@middy/core';
import createLoggingMiddleware from "middy-pino";

const handler = middy()
    // debug logs will appear on roughly half of all requests
    .use(createLoggingMiddleware({
        name: 'my-service-name', 
        trackerOptions: {
            requestMixin(event) {
                return {
                    customCorrelationId: event.headers['custom-correlation-id']
                }
            }
        }
    }))
    .handler(async (event, context) => {
        context.log.info('handling event'); // includes `customCorrelationId` field in each log
    });

Sample Debug Logs

import middy from '@middy/core';
import createLoggingMiddleware from "middy-pino";

const handler = middy()
    // debug logs will appear on roughly half of all requests
    // below is equivalent to setting MIDDY_PINO_DEBUG_RATE environment variable to '0.5'
    .use(createLoggingMiddleware({ name: 'my-service-name', debugRate: 0.5 }))
    .handler(async (event, context) => {
        context.log.debug('handling event');
    });