Access Log Parser

A lightweight Node.js module for parsing Apache-style HTTP access logs

This module extracts key fields—IP address, request method, URL/query, timestamps, referrer, response code, response size, and user-agent details—from standard Apache access log lines. It is designed to be small, dependency-light, and easy to integrate into log-processing pipelines.

✨ Features

• Extracts:

  • IP address (including handling of IPv6 ::1 → 127.0.0.1)
  • Timestamp → JavaScript Date object
  • HTTP method
  • Query/path
  • Referrer
  • Response code
  • Response size
  • Full parsed user-agent (via parse-user-agent)

• Provides a parseLine() helper that extracts all values at once

• No external Apache configuration required—parses raw log lines

📦 Installation

npm install @outlawdesigns/access-log-parser

🚀 Usage

const fs = require('fs');
const AccessLogParser = require('@outlawdesigns/access-log-parser');
const logPath = '/var/log/apache2/access.log';

let data = fs.readFileSync(logPath, 'utf8').split("\n");

data.forEach((line) => {
  console.log(AccessLogParser.parseLine(line));
});

Sample output:

{
  "ip_address": "127.0.0.1",
  "responseCode": "200",
  "requestDate": "2024-01-01T12:34:56.000Z",
  "requestMethod": "GET",
  "query": "/index.html",
  "referrer": "https://example.com",
  "responseSize": "5321",
  "ua": "Mozilla/5.0...",
  "browser": { ... },
  "engine": { ... },
  "os": { ... },
  "device": { ... }
}

🧩 API Reference

parseIp(logStr)

Returns the client IP address. IPv6 loopback (::1) is mapped to 127.0.0.1.

parseDate(logStr)

Returns a JavaScript Date based on the Apache timestamp.

parseTimeZone(logStr)

Returns the timezone offset (e.g. -0600).

parseMethod(logStr)

Extracts the HTTP verb (GET, POST, etc.).

parseQuery(logStr)

Extracts the request target (path/query).

parseReferrer(logStr)

Returns the request referrer, if present.

parseResponseCode(logStr)

Extracts the numeric HTTP status code.

parseResponseSize(logStr)

Response payload size in bytes.

parseUserAgent(logStr)

Parses the User-Agent header using parse-user-agent.

parseLine(logStr)

Returns a full object with all possible parsed fields.

🛠 Example: Processing a Log Stream

const readline = require('readline');
const fs = require('fs');
const parser = require('@outlawdesigns/access-log-parser');

const rl = readline.createInterface({
  input: fs.createReadStream('/var/log/apache2/access.log'),
  crlfDelay: Infinity
});

rl.on('line', line => {
  const record = parser.parseLine(line);
  if (record) console.log(record);
});

🧪 Notes

• The parser assumes your access logs follow an Apache combined-style pattern.
• Malformed or incomplete lines return false.
• All regexes are intentionally optimized for speed and low overhead.

📄 License

MIT