clew-logger/logger.js

const winston = require('winston');
const LokiTransport = require('winston-loki');
const context = require('./context');
const moment = require('moment-timezone');

module.exports = {
    create: (config) => {

        var transports = [
            new winston.transports.Console({})
        ]

        const lokiConfig = {
            host: config.prodHost,
            labels: {
                app: config.appTag
            },
            json: true,
            format: winston.format.json(),
            onConnectionError: (err) => console.error(err)
        }
        if(config.prod) {
            transports.push(new LokiTransport(lokiConfig));
        }



        const logger = winston.createLogger({
            format: winston.format.combine(
                winston.format((info, opts) => {
                    try { 
                        info.requestId = context.getRequestId();
                        info.metadata = context.getMetadata();
                    } catch(error) {
                        //no context available, ignore attempt to attach requestId
                    }

                    info.time = moment();
                    return info;
                })(),
                winston.format.json()
            ),
            transports: transports
        });
        return logger;
    }
}