Querying Logs

If you’re logging to a database or an external service, querying logs can be useful. For instance, with MongoDB and winston-mongodb, you can query logs like this:

const winston = require('winston');
require('winston-mongodb');

const logger = winston.createLogger({
  level: 'info',
  format: winston.format.combine(
    winston.format.timestamp(),
    winston.format.json()
  ),
  transports: [
    new winston.transports.MongoDB({
      db: 'mongodb://localhost/logs',
      collection: 'log',
      level: 'info'
    })
  ]
});

// Querying logs from MongoDB
const MongoClient = require('mongodb').MongoClient;

MongoClient.connect('mongodb://localhost/logs', function (err, client) {
  if (err) throw err;

  const db = client.db('logs');
  const collection = db.collection('log');

  collection.find({ level: 'info' }).toArray(function (err, docs) {
    if (err) throw err;

    console.log(docs);
    client.close();
  });
});