Syslog logging for node.js. Continuation of ain
npm install ain2-papandreou
Brain-free syslog** logging for
node.js.
Ain written with full compatibility with node.js console module. It
implements all console functions and formatting. Also ain supports UTF-8
(tested on Debian Testing/Sid).
Ain send messages by UDP to 127.0.0.1:514 by default, but can also be
configured to use a unix datagram socket, eg. /dev/log, although that's
a less scalable setup. See RFC 3164.
*In the Phoenician alphabet letter "ain" indicates eye.
**All examples tested under Debian Squeeze rsyslog. On other operating
systems and logging daemons settings and paths may differ.
You can install ain as usual - by copy "ain" directory in your~/.node_libraries or via npm
npm install ain2
Usage of ain is very similar to node.js console. Following example
demonstrates the replacement of the console:
var console = require('ain2');
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
By default ain sets following destinations:
* TAG - __filename
* Facility - user (1)
* Severity threshold - 'debug' (lets all messages through)
* Socket type - udp
* HOSTNAME - localhost
* PORT - 514
You can change them by set function. set function is chainable.
var logger = require('ain2')
.set('node-test-app', 'daemon', 'error', 'udp', 'devhost', 3000);
logger.error('some error');
logger.warn('some warning');
... and in /var/log/daemon.log:
Dec 5 07:08:58 devhost node-test-app[10045]: some error
set function takes up to six arguments, all of which are
optional. The first four are always tag, facility,socketType, and severityThreshold. If socketType is specified
as udp, the next two arguments will be interpreted as hostname
and port. If socketType is unixDatagramSocket, the fourth argument is
interpreted as the path of the socket, defaulting to /dev/log.
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 facility by String or Number:
logger.set('node-test-app', 3);
logger.set('node-test-app', 'daemon');
Also you can set TAG, Facility and HOSTNAME separatelly by setTag,setFacility and setHostname functions. All of them is chainable too.
You can get all destinations by theese properties:
* tag TAG
* facility Numerical representation of RFC 3164 facility
* hostname HOSTNAME
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 message with desired severity level you can use send function:
logger.send('message', 'alert');
send function takes two arguments: message and optional severity level. By
default, severity level is notice.
After importing ain already has default logger. Everything that was
described above - just about it.
If you need log message with different TAG, facility and HOSTNAME
without touching default logger, you can get independent instance of logger
by get function.
var logger = require('ain').set('node-test-app', 'daemon', null, 'udp', 'devhost');
logger.warn('some warning');
var anotherLogger = logger.get(logger.tag, 'local0', null, 'udp', logger.hostname);
anotherLogger.log('another message');
var yetAnotherLogger = logger.get(logger.tag, 'local0', 'warn', 'unixDatagramSocket', '/dev/log');
yetAnotherLogger.log('yet another message');
get function takes three arguments - as well as set function and return
new logger object. This object is just new instance of "logger" and has all
ain functions (including get).