flaschenpost

flaschenpost

flaschenpost is a logger for cloud-based applications.

A /ˈflaʃənˌpɔst/ is a „message written on a scrap of paper, rolled-up and put in an empty bottle and set adrift on the ocean; traditionally, a method used by castaways to advertise their distress to the outside world”. (from Wiktionary)

Installation

$ npm install flaschenpost

Quick start

First you need to integrate flaschenpost into your application.

var flaschenpost = require('flaschenpost');

You need to provide the name and version of your application. For that call the use function and specify an appropriate object.

flaschenpost.use('module', {
  name: 'foo',
  version: '0.0.1'
});

Please note that if you specify additional properties, these properties are ignored. This allows you to hand over your package.json file.

flaschenpost.use('module', require('./package.json'));

Using a logger

Once you have set up flaschenpost, you can call its getLogger function to acquire a logger.

var logger = flaschenpost.getLogger();

If you want to use multiple loggers in your application, you may provide a string as parameter for getLogger that identifies the source from where you send log messages. This may be the name of the current file.

var logger = flaschenpost.getLogger(__filename);

Then you can use the functions fatal, error, warn, info and debug to write log messages. Simply provide the message you want to log as a parameter.

logger.info('App started.');

Formatting log messages

If you want to use placeholders in the log message, embrace them in double curly braces. Additionally, specify an object that contains the values.

logger.info('App {{name}} started.', {
  name: 'foo'
});

You can use as many placeholders as you like. Values in the object that do not have a counterpart in the log message are ignored.

Handling meta data

If you want to provide additional meta data, add a metadata key to the parameter object and provide the meta data.

logger.info('App {{name}} started.', {
  name: 'foo',
  metadata: {
    foo: 'bar',
    baz: 23
  }
});

Enabling and disabling log levels

By default, only the log levels fatal, error, warn and info are printed to the console. If you want to change this, set the environment variable LOG_LEVELS to the comma-separated list of desired log levels.

$ export LOG_LEVELS=debug,info

Setting custom log levels

If you want to change the default log levels, i.e. define other log levels, change colors or define which log levels are enabled by default, call the use function of flaschenpost.

flaschenpost.use('levels', {
  fatal: {
    color: 'blue',
    enabled: true
  },
  error: {
    color: 'red',
    enabled: true
  },
  warn: {
    color: 'yellow',
    enabled: true
  },
  info: {
    color: 'green',
    enabled: true
  },
  debug: {
    color: 'white',
    enabled: false
  }
});

Using the Express middleware

If you are writing an Express-based application and you use morgan as logger, you can integrate flaschenpost.

For that, provide the stream property when setting up morgan and call flaschenpost's Middleware constructor function with the desired log level.

app.use(morgan('combined', {
  stream: new flaschenpost.Middleware('info')
}));

Running the build

This module can be built using Grunt. Besides running the tests, this also analyses the code. To run Grunt, go to the folder where you have installed flaschenpost and run grunt. You need to have grunt-cli installed.

$ grunt

License

The MIT License (MIT) Copyright (c) 2013-2014 the native web.

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.