kth-node-log

Logging module for Node.js applications.

Usage

The package will respect NODE_ENV and output serialized JSON in production and use ordinary output for development. To override this, set LOGGING_OUTPUT_FORMAT to development or production.

In your application

const log = require("kth-node-log");

// in application setup, see full options below
log.init({
  console: {
    enabled: true
  }
});

// log usage
log.info("hello from info, log level usually used in setup");
log.warn("error that code handled and can recover from");
log.error({ err: err }, "error that should be fixed in code");
log.fatal("a really bad error that will crash the application");
log.debug({ req: req, res: res }, "log a request and response, basic dev log");
log.trace("granular logging, rarely used");

// child logger
// add custom values to all of the logs
const myLog = log.child({ custom: "value" });
myLog.info("hello");

Options

log.init({
  // name of the logger, usually the same as application name
  name: "node-logger",

  // application name, e.g. places-web
  app: "node-app",

  // usually set this to process.env.NODE_ENV
  env: "dev",

  // default logging level, can be overridden in stream configs
  level: bunyan.INFO,

  // use bunyan's own serializers
  serializers: {
    req: bunyan.stdSerializers.req,
    res: bunyan.stdSerializers.res,
    err: bunyan.stdSerializers.err
  },

  // include source file, only enable in dev mode
  src: false,

  // enable debug logging
  debugMode: false,

  // stream, log to logstash using the lumberjack protocol
  // see bunyan-lumberjack for more details
  logstash: {
    enabled: false,
    level: null,
    tlsOptions: {
      host: "",
      port: 0,
      ca: []
    },
    lumberjackOptions: {
      maxQueueSize: 500,
      allowDrop: function(entry) {
        // bunyan-lumberjack example is wrong,
        // this method should be called "shouldKeep"
        // return false to drop message, true to keep message
        return entry.bunyanLevel > bunyan.INFO;
      }
    }
  },

  // stream, log to stdout using bunyan-format
  // see bunyan-format for more details
  console: {
    enabled: false,
    level: null,
    format: {
      outputMode: "short"
    }
  },

  // stream, log raw json to stdout
  stdout: {
    enabled: false,
    level: null
  }
});