JarCastingpy-logging
Javascript logging library based on the Python logging module.
Main features:
- Hierarchical organization of loggers.
- Handlers for various ways of log records processing.
- Filters for very precise log records filtering.
- Formatters for custom layout of log records in the final output.
More about Python logging here: https://docs.python.org/2/library/logging.html
Installation
npm install py-logging
Documentation
https://github.com/jose-pleonasm/py-logging/tree/master/API.md
Usage
A simplest way:
var logging = require('py-logging');
logging.info('My message to the world.');
// will do nothing, because default level is WARNING
logging.warning('My another message to the world.');
// will print a message to the console:
// WARNING:root:My another message to the world.
Recording log records in a file:
var logging = require('py-logging');
// for recording log records to the file is necessary to install nodekit
require('py-logging/nodekit').install(logging);
logging.basicConfig({ filename: 'example.log', level: 'DEBUG' });
logging.debug('I am going to say something...');
logging.info('Hello!');
// will create a file "example.log" with content like this:
// DEBUG:root:I am going to say something...
// INFO:root:Hello!
Custom layout of log records:
var logging = require('py-logging');
logging.basicConfig({
format: '%(asctime) - %(levelname) - %(message)',
timeFormat: '%ISO',
level: 'DEBUG'
});
logging.info('So far so good.');
// 2017-02-12T15:02:02.910Z - INFO - So far so good.
Logging an error:
var logging = require('py-logging');
try {
someDangerousFunction();
}
catch (error) {
logging.error('An error occurred during the function call:', error);
}
// ERROR:root:An error occurred during the function call:
// ReferenceError: someDangerousFunction is not defined
// at Object.<anonymous> (/example.js:6:2)
// at Module._compile (module.js:571:32)
// at Object.Module._extensions..js (module.js:580:10)
// at Module.load (module.js:488:32)
// at tryModuleLoad (module.js:447:12)
// at Function.Module._load (module.js:439:3)
// at Module.runMain (module.js:605:10)
// at run (bootstrap_node.js:418:7)
// at startup (bootstrap_node.js:139:9)
// at bootstrap_node.js:533:3
Instantiating your own Logger:
var logging = require('py-logging');
var logger = logging.getLogger('name');
logging.basicConfig({ level: 'DEBUG' });
logger.info('Something specific for this logger.');
// INFO:name:Something specific for this logger.
More complex configuration:
var logging = require('py-logging');
// for recording log records to the file is necessary to install nodekit
require('py-logging/nodekit').install(logging);
var simpleFormatter = new logging.Formatter('%(levelname) %(name) %(message)');
var verboseFormatter = new logging.Formatter('%(asctime) %(levelname) %(name) %(message)');
var consoleHandler = new logging.ConsoleHandler();
var fileHandler = new logging.RotatingFileHandler('./example.log');
var foo = logging.getLogger('foo');
var bar = logging.getLogger('foo.bar');
consoleHandler.setFormatter(simpleFormatter);
consoleHandler.setLevel(logging.DEBUG);
foo.addHandler(consoleHandler);
foo.setLevel(logging.DEBUG);
fileHandler.setFormatter(verboseFormatter);
fileHandler.setLevel(logging.INFO);
bar.addHandler(fileHandler);
foo.info('First message.');
// will print a message to the console:
// INFO foo First message.
bar.info('Second message.');
// will print a message to the console:
// INFO foo.bar Second message.
// and into the file:
// 2017-02-12 15:43:52 INFO foo.bar Second message.
Or by a configuration object (can be JSON):
var logging = require('py-logging');
// for recording log records to the file is necessary to install nodekit
require('py-logging/nodekit').install(logging);
logging.config({
'version': 1,
'formatters': {
'simple': {
'format': '%(levelname) %(name) %(message)'
},
'verbose': {
'format': '%(asctime) %(levelname) %(name) %(message)'
}
},
'handlers': {
'console': {
'class': 'logging.ConsoleHandler',
'formatter': 'simple',
'level': 'DEBUG'
},
'file': {
'class': 'logging.RotatingFileHandler',
'filename': './example.log',
'formatter': 'verbose',
'level': 'INFO'
}
},
'loggers': {
'foo': {
'level': 'DEBUG',
'handlers': ['console']
},
'foo.bar': {
'handlers': ['file']
}
}
});
logging.getLogger('foo').info('First message.');
// will print a message to the console:
// INFO foo First message.
logging.getLogger('foo.bar').info('Second message.');
// will print a message to the console:
// INFO foo.bar Second message.
// and into the file:
// 2017-02-12 15:43:52 INFO foo.bar Second message.