Syslog logging for node.js. Continuation of ain
npm install ain2console module. It
console functions and formatting. Also ain supports UTF-8
127.0.0.1:514 or to the a unix socket;
rsyslog. On other operating
~/.node_modules or via npm
javascript
var SysLogger = require('ain2');
var console = new SysLogger();
console.log('notice: %d', Date.now());
console.info('info');
console.error('error');
`
After launch in /var/log/user you can see the following:
Dec 5 06:45:26 localhost ex.js[6041]: notice: 1291513526013
Dec 5 06:45:26 localhost ex.js[6041]: info
Dec 5 06:45:26 localhost ex.js[6041]: error
Note: you need to ensure syslog is listening on UDP port 514 for this example to work. On Ubuntu, for example, you would need to edit `/etc/rsyslog.conf`, add/uncomment the following lines, and ensure rsyslog is restarted:
`
provides UDP syslog reception
$ModLoad imudp
$UDPServerAddress 127.0.0.1
$UDPServerRun 514
`
Singleton logger
If you want to have a singleton that points to the same object whenever you do a require, use the following:
`javascript
require('ain2').getInstance();
`
If you use this, please be beware of this:
`javascript
require('ain2').getInstance() === require('ain2').getInstance();
=> true
`
As opposed to:
`javascript
var SysLogger = require('ain2');
new SysLogger() === new SysLogger();
=> false
`
Changing destinations
By default ain sets following destinations:
* TAG - __filename
* Facility - user (1)
* HOSTNAME - localhost
* PORT - 514
* Transport - UDP
You can change them by passing in the params to the constructor or by
using the set function. The set function is chainable.
`javascript
var SysLogger = require('ain2');
var logger = new SysLogger({tag: 'node-test-app', facility: 'daemon', hostname: 'devhost', port: 3000});
logger.warn('some warning');
`
... and in /var/log/daemon.log:
Dec 5 07:08:58 devhost node-test-app[10045]: some warning
The set function takes one argument, a configuration object which can contain the following keys:
* tag - defaults to __filename
* facility - defaults to user
* hostname - defaults to require('os').hostname()
* port - defaults to 514
* transport - defaults to 'UDP'
* path - path to filesystem socket if using unix_dgram transport
* messageComposer - a custom function to compose syslog messages
All of these are optional. If you provide a hostname transport is automatically set to UDP
tag and hostname arguments is just RFC 3164 TAG and HOSTNAME of
your messages.
facility is little more than just name. Refer to Section 4.1.1 of
RFC 3164 it can be:
## String Description
-----------------------
0 kern kernel messages
1 user user-level messages
2 mail mail system
3 daemon system daemons
4 auth security/authorization messages
5 syslog messages generated internally by syslog daemon
6 lpr line printer subsystem
7 news network news subsystem
8 uucp UUCP subsystem
16 local0 local use 0
17 local1 local use 1
18 local2 local use 2
19 local3 local use 3
20 local4 local use 4
21 local5 local use 5
22 local6 local use 6
23 local7 local use 7
You can set the facility by String or Number:
logger.set({tag: 'node-test-app', facility: 3});
logger.set({tag: 'node-test-app', facility: 'daemon'});
Also you can set TAG, Facility, HOSTNAME, PORT, and transport separately by setTag,
setFacility, setHostname, setPort, setTransport and setMessageComposer functions. All of them are chainable too.
You can get all destinations by these properties:
* tag TAG
* facility Numerical representation of RFC 3164 facility
* hostname HOSTNAME
* port PORT
Callbacks
Ain provides an optional callback after a message has been sent to the socket (udp and unix socket).
The callback is passed up unaltered from node.
Because ain supports a simplified printf format, the callback has to be the last parameter.
`javascript
var SysLogger = require('ain2');
var console = new SysLogger();
console.info('info', function(err, bytes){
// callback received
});
console.log('notice: %d', Date.now(), function(err, bytes){
// callback received
});
`
Custom message composer
`javascript
var SysLogger = require('ain2');
var console = new SysLogger();
console.setMessageComposer(function(message, severity){
return new Buffer('<' + (this.facility * 8 + severity) + '>' +
this.getDate() + ' ' + '[' + process.pid + ']:' + message);
});
`
The default implementation looks this:
`javascript
SysLogger.prototype.composeSyslogMessage = function(message, severity) {
return new Buffer('<' + (this.facility * 8 + severity) + '>' +
this.getDate() + ' ' + this.hostname + ' ' +
this.tag + '[' + process.pid + ']:' + message);
}
`
Logging
As noticed before ain implements all console functions. Severity level is
referenced to RFC 3164:
# String Description
-----------------------
0 emerg Emergency: system is unusable
1 alert Alert: action must be taken immediately
2 crit Critical: critical conditions
3 err Error: error conditions
4 warn Warning: warning conditions
5 notice Notice: normal but significant condition
6 info Informational: informational messages
7 debug Debug: debug-level messages
Ain console-like functions behaviour is fully compatible to node.js and
logs messages with different severity levels:
* log - notice (5)
* info - info (6)
* warn - warn (4)
* error - err (3)
* dir - notice (5)
* time, timeEnd - notice (5)
* trace - err (3)
* assert - err (3)
To log a message with the desired severity level you can use the send function:
`javascript
logger.send('message', 'alert');
`
The send` function takes two arguments: message and optional severity level. By