@sylphx/cat-http

HTTP request/response serializers for @sylphx/cat logger

0.75 KB • Express/Fastify compatible • Automatic header redaction

Installation

npm install @sylphx/cat @sylphx/cat-http

Description

Provides standardized serializers for HTTP requests and responses in @sylphx/cat. Automatically extracts relevant information from request/response objects while redacting sensitive headers (authorization, cookies, API keys). Compatible with Express, Fastify, Koa, Next.js, and standard Node.js HTTP objects.

Usage Examples

Express Middleware

import { createLogger } from '@sylphx/cat'
import { httpSerializers } from '@sylphx/cat-http'
import express from 'express'

const logger = createLogger({
  serializers: httpSerializers
})

const app = express()

app.use((req, res, next) => {
  logger.info({ req }, 'Incoming request')
  next()
})

app.get('/users/:id', (req, res) => {
  res.json({ id: req.params.id })
  logger.info({ req, res }, 'Request completed')
})

Output:

{
  "level": "info",
  "message": "Incoming request",
  "req": {
    "method": "GET",
    "url": "/users/123",
    "headers": { "user-agent": "...", "authorization": "[REDACTED]" },
    "params": { "id": "123" },
    "remoteAddress": "::1"
  }
}

Standalone Request Serialization

import { createLogger } from '@sylphx/cat'
import { requestSerializer, responseSerializer } from '@sylphx/cat-http'

const logger = createLogger({
  serializers: {
    req: requestSerializer,
    res: responseSerializer
  }
})

// In your HTTP handler
logger.info({ req, res }, 'HTTP request processed')

Next.js API Route

import { createLogger } from '@sylphx/cat'
import { httpSerializers } from '@sylphx/cat-http'
import type { NextApiRequest, NextApiResponse } from 'next'

const logger = createLogger({
  serializers: httpSerializers
})

export default function handler(req: NextApiRequest, res: NextApiResponse) {
  logger.info({ req }, 'API request received')

  res.status(200).json({ message: 'Success' })

  logger.info({ req, res }, 'API request completed')
}

API Reference

httpSerializers

Combined serializers object containing both request and response serializers.

import { httpSerializers } from '@sylphx/cat-http'

const logger = createLogger({
  serializers: httpSerializers
})

Includes:

• req - Request serializer
• request - Alias for req
• res - Response serializer
• response - Alias for res

requestSerializer(req: any): SerializedRequest

Serializes HTTP request objects.

Extracts:

• method - HTTP method (GET, POST, etc.)
• url - Request URL
• headers - HTTP headers (sensitive headers redacted)
• query - Query parameters (if available)
• params - Route parameters (if available)
• remoteAddress - Client IP address
• remotePort - Client port
• protocol - HTTP/HTTPS
• httpVersion - HTTP version

Sensitive headers redacted:

• authorization
• cookie
• x-api-key
• x-auth-token
• x-csrf-token
• x-session-id

responseSerializer(res: any): SerializedResponse

Serializes HTTP response objects.

Extracts:

• statusCode - HTTP status code
• statusMessage - Status message
• headers - Response headers (sensitive headers redacted)

Sensitive headers redacted:

• set-cookie
• authorization
• x-api-key

Framework Compatibility

Express

app.use((req, res, next) => {
  logger.info({ req }, 'Request received')
  res.on('finish', () => {
    logger.info({ req, res }, 'Request completed')
  })
  next()
})

Fastify

fastify.addHook('onRequest', (request, reply, done) => {
  logger.info({ req: request.raw }, 'Request received')
  done()
})

Koa

app.use(async (ctx, next) => {
  logger.info({ req: ctx.request }, 'Request received')
  await next()
  logger.info({ req: ctx.request, res: ctx.response }, 'Request completed')
})

Node.js HTTP

import { createServer } from 'http'

const server = createServer((req, res) => {
  logger.info({ req }, 'Request received')
  res.writeHead(200)
  res.end('Hello')
  logger.info({ req, res }, 'Request completed')
})

Package Size

• Minified: ~2.2 KB
• Minified + Gzipped: 0.75 KB
• No additional dependencies

Links

• Main Documentation
• GitHub Repository
• npm Package

Related Packages

• @sylphx/cat - Core logger
• @sylphx/cat-redaction - Advanced PII redaction
• @sylphx/cat-tracing - Distributed tracing

License

MIT © Kyle Zhu