@vaibhavkaul69/monitoring-logger/lib/logger.js

Reusable monitoring and logging middleware for backend servicses

const { createLogger, format } = require("winston");
const LokiTransport = require("winston-loki");
require("dotenv").config();

const logger = createLogger({
  format: format.combine(format.timestamp(), format.json()),
  transports: [
    new LokiTransport({
      host: process.env.LOKI_URL || "http://localhost:3100",
      labels: { app: "backend-service" },
      onConnectionError: (err) => {
        console.error(
          "[monitoring-logger-error] Loki connection failed:",
          err.message
        );
      },
    }),
  ],
});

const log = (level, messagePayload, labels) => {
  if (!labels) {
    console.error("[monitoring-logger-error] labels cannot be empty");
    return;
  }

  logger.log({
    level: level,
    message: JSON.stringify(messagePayload),
    labels: labels,
  });
};

const logDebug = (payload, labels) => log("debug", payload, labels);
const logInfo = (payload, labels) => log("info", payload, labels);
const logError = (payload, labels) => log("error", payload, labels);

module.exports = {
  logger,
  logInfo,
  logError,
  logDebug,
};