szaydel/node-kstat

A node.js addon for reading Solaris kstats

node-kstat

This repository is part of the Triton Data Center project. See the contribution guidelines and general documentation at the main Triton project page.

A node.js binding to the illumos kstat interface. This allows one to read kernel statistics via the kstat framework. It is likely to work unmodified on Solaris too.

Usage

The kstat module exports a single class, Reader that has the following methods:

Reader():  Takes an optional object specifying the kstats to read.  This
           object may have the following members:

           class    =>  optional string denoting class of kstat(s) to read
           module   =>  optional string denoting module of kstat(s) to read
           name     =>  optional string denoting name of kstat(s) to read
           instance =>  optional integer denoting instance of kstat(s) to read

           Together, these members form a specification of kstats to read.

read():    Returns an array of kstats that match the specification with
           which the reader instance was constructed *and* an optional
           specification passed to this function.  Each element of the
           array is an object that contains the following members:

           class    =>  string denoting class of kstat
           module   =>  string denoting module of kstat
           name     =>  string denoting name of kstat
           instance =>  integer denoting instance of kstat
           snaptime =>  nanoseconds since boot of this snapshot
           data     =>  an object containing the named kstat data itself

Examples

Here is a simple program that dumps the kstats of class mib2:

var kstat = require('kstat');
var util = require('util');
var reader = new kstat.Reader({ 'class': 'mib2' } );
console.log(util.inspect(reader.read()));

Here is a the same program that reads only the mib2 class kstats from the icmp module:

var kstat = require('kstat');
var util = require('util');
var reader = new kstat.Reader({ 'class': 'mib2', module: 'icmp' } );
console.log(util.inspect(reader.read()));

Finally, here is a simple program that prints the number of ICMP datagrams received per second:

var kstat = require('kstat');
var reader = new kstat.Reader({ 'class': 'mib2', module: 'icmp' } );

var data = [];
var gen = 0;

setInterval(function() {
	data[gen] = reader.read()[0];
	gen ^= 1;

	if (!(data[0] && data[1]))
		return;

	console.log(data[gen ^ 1].data.inDatagrams - data[gen].data.inDatagrams);
}, 1000);

You can find further example programs in the examples directory.

License

MIT.