logsaw

logsaw is a simple JSON file-based logger for node.

Installation

npm

npm install logsaw

GitHub

npm install https://github.com/martinrue/logsaw/tarball/master

Configuration

To change the default config, call configure:

var logger = require('logsaw');

logger.configure({
  console: true,
  verbose: true,
  directory: __dirname + '/logs'
});

Options

| Key | Default Value | Description | |-------------|--------------------------|------------------------------------------------------| | console | true if not production | display logs on console | | verbose | false | display complete log object on console | | debug | false | save debug logs to log file | | generators | false | allow log functions to be yielded from ES6 generator | | directory | process.cwd() + 'logs' | the directory to write log files to (created if new) |

API

logsaw exposes 4 functions: debug(), info(), warn() and error(). All functions take a single object argument which may contain message, context and data fields. You may specify a type field in calls to info() to create custom log types. Calls to debug() are saved to the log file only if { debug: true } is set in config.

Example

var logger = require('logsaw');

// creates a debug log (saved to the log file if debug is set to true in config)
logger.debug({ message: 'some debug message', data: { /*...*/ } });

// creates an info log
logger.info({ message: 'user signed up' });

// creates a custom user-signup log
logger.info({ type: 'user-signup', message: 'user signed up' });

// creates a warning log with a context
logger.warn({ message: 'account locked', context: '[email protected]' });

// creates an error log with associated err data
logger.error({ message: 'something went wrong', data: err });

Callback

If { generators: false } is set (default), an optional callback can be supplied as the last argument to the 4 logging functions to be notified once the underlying write operation completes.

Generators

If { generators: true } is set, you can optionally yield any of the 4 log functions from within Co, or similar.

Logs

Filename

Log files are created based on the current date (e.g. 2014-07-22.log) and written to the config directory.

Format

Each log file consists of a line-delimited JSON entry of the form:

{
  "type":"error",
  "message":"something went wrong",
  "time":"2014-07-22T19:30:00.630Z",
  "data":"{ err: 'error info' }",
  "context":"[email protected]"
}

Context

The context field of a log entry is intended to hold a scalar value that can be used to group sets of logs together.

You could set it to a user's email address to associate a series of logs with a user, you could set it to a request ID to associate a series of logs with an HTTP request, or you could set it to some other meaningful value.

License

MIT