logster provides a configurable node logging facility that can write to various destinations. It provides the following loggers "out of the box":
- consolelogger
- streamlogger
- mongologger
$ npm install logster
Loggers are objects that have a name property a log function, and optionally a drain function.
Although logster already comes with a console logger, here is an example of how you could create your own:
consolelogger.js
var format = require('logster').textFormatter.format;
module.exports = {
name: 'console',
write: function(logEntry) {
console.log(format(logEntry));
}
};
logster provides a default formatter (textformatter) that standardizes the look of log entries for text-based output. Both consolelogger and streamlogger have a formatter property set to this. You can set the formatter property to your own object that has a format function. The function should have a logEntry parameter and return a string.
The log interface does not require callbacks; however, log writes still need to be properly serialized. loggers that write asynchronously, such as mongologger use the async package to queue log entries. Async loggers should provide a drain callback that can be used to check if the queue has been drained. This is important to ensure the process does not exit with pending writes.
To implement your own async logger, take a look at the source for mongologger.js.
logster uses the same values as syslog. When creating a new log, set the severity level using values defined in severity.js.
Note: the first parameter to the Log constructor can be the number value or the level name (case-insensitive).
The following are all equivalent:
var severity = require('logster').severity;
log = new Log(severity.DEBUG, consoleLogger);
log = new Log('DEBUG', consoleLogger);
log = new Log('debug', consoleLogger);
log = new Log(7, consoleLogger);
console.log(severity.str(7)); // => 'DEBUG'
| level | value | purpose |
|---|---|---|
| NONE | -1 | don't log |
| EMERGENCY | 0 | system is unusable |
| ALERT | 1 | action must be taken immediately |
| CRITICAL | 2 | critical conditions |
| ERROR | 3 | error conditions |
| WARNING | 4 | warning conditions |
| NOTICE | 5 | normal but significant condition |
| INFO | 6 | informational messages |
| DEBUG | 7 | debug-level messages |
var Log = require('logster').Log
, severity = require('logster').severity
, consoleLogger = require('logster').consoleLogger
, log
;
log = new Log(severity.DEBUG, consoleLogger);
var Log = require('logster').Log
, severity = require('logster').severity
, streamLogger = require('logster').streamLogger
, log
;
streamLogger.stream = fs.createWriteStream(__dirname + '/stream.log');
log = new Log(severity.DEBUG, streamLogger);
var Log = require('logster').Log
, severity = require('logster').severity
, mongoLogger = require('logster').mongoLogger
, mongodb = require('mongodb')
, mongoUri = '...'
;
mongodb.MongoClient.connect(mongoUri, function(err, client) {
mongoLogger.db = client;
var log = new Log('debug', mongoLogger);
log.info('hello');
// check that async loggers have finished draining
// the log queue before exiting the process...
log.drain(function() {
console.log('finished writing all log entries to mongo');
process.exit(0);
});
});
var log = new Log(severity.DEBUG, consoleLogger, mongoLogger, ...);
Note: this version doesn't support different logger severity levels.
log.info('hello');
Output:
[Mon Jan 13 2014 06:42:54 GMT-0800 (PST)] INFO hello
log.info({ category: 'api' }, 'hello');
// define category constants to make using categories easier:
var API = { category: 'api' }
, DATA = { category: 'data' }
;
...
log.info(API, 'received GET request');
log.info(DATA, 'retrieved some data');
Output:
[Mon Jan 13 2014 06:42:54 GMT-0800 (PST)] INFO (api) hello
Parameters passed after message are either added to a data property or to a tags property array, depending on whether they are objects or primitive values.
log.info('a log entry with lots of custom data attributes',
'interesting',
'cool',
'stuff',
{ userid: 'tester' },
{ moredata: true, stuff: 'lots' });
Output:
[Mon Jan 13 2014 13:20:20 GMT-0800 (PST)] INFO a log entry with lots of custom data attributes {
data: { userid: 'tester', moredata: true, stuff: 'lots' },
tags: [ 'interesting', 'cool', 'stuff' ] }
Mongo document (using mongologger)
{
"timestamp" : ISODate("2014-01-13T21:23:49.744Z"),
"category" : "",
"level" : "INFO",
"levelCode" : 6,
"message" : "a log entry with lots of custom data attributes",
"data" : {
"userid" : "tester",
"moredata" : true,
"stuff" : "lots"
},
"tags" : [
"interesting",
"cool",
"stuff"
],
"_id" : ObjectId("52d45965b565194aa9b39676")
}
MIT License
Copyright (c) 2014, Tony Pujals (http://tonypujals.io/contact/)
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.