index.js

var _os = require('os');
var _param = require('./param.json');
var _request = require('request');
var _tools = require('graphdat-plugin-tools');

var _httpOptions; // username/password options for the URL
var _previous = {}; // remember the previous poll data so we can provide proper counts

// At a minimum, we need a way to contact apache
if (!_param.url)
{
    console.error('To get statistics from Apache, a statistics URL is required');
    process.exit(-1);
}

// if there is no http or https, guess its http
if (_param.url.substring(0,7) !== 'http://' && _param.url.substring(0,8) !== 'https://')
    _param.url = 'http://' + _param.url;

// tell apache to make the output 'machine readable'
if (_param.url.slice(-5) !== '?auto')
    _param.url += '?auto';

// This this is a URL and we have a name and password, then we need to add an auth header
if (_param.username)
    _httpOptions = { auth: { user: _param.username, pass: _param.password, sendImmediately: true } };

// If we do not have a source, we prefix everything with the servers hostname
_param.source = (_param.source || _os.hostname()).trim();

// If you do not have a poll intevarl, use 1000 as the default
_param.pollInterval = _param.pollInterval || 1000;

// get the natural difference between a and b
function diff(a, b)
{
    if (a == null || b == null)
        return 0;
    else
        return Math.max(a - b, 0);
}

function handleError(err)
{
    console.error(err);
    process.exit(-1);
}

function poll(cb)
{
    // call apache to get the stats page
    _request.get(_param.url, _httpOptions, function(err, resp, body)
    {
        if (err)
            return handleError(err);
        if (resp.statusCode !== 200)
           return handleError(new Error('Apache returned with an error - recheck the URL and credentials that you provided'));
        if (!body)
           return handleError(new Error('Apache statistics return empty'));

        var current = {};
        var lines = body.split('\n');
        lines.forEach(function(line)
        {
            // skip over empty lines
            if (!line)
                return;

           // parse the record
            var data = line.split(':');
            var key = data[0].trim();
            var value = data[1];

            if (value == null || value === '')
                return;

            var fValue = parseFloat(value,10);
            if (fValue === 0 || fValue)
                current[key] = fValue;
            else
                current[key] = value.trim();
        });

        var totalWorkers =  (current['BusyWorkers'] || 0) + (current['IdleWorkers'] || 0);
        var busyRatio = (totalWorkers) ? current['BusyWorkers'] / totalWorkers : 0;

        var requests = diff(current['Total Accesses'], _previous['Total Accesses']);

        // because of the interval cut off lines, on a really slow site you will get 0's
        // use the previous value if that happens
        current['totalBytes'] = diff(current['Total kBytes'], _previous['Total kBytes']) * 1024;
        if (requests > 0 && current['totalBytes'] ===  0)
            current['totalBytes'] = _previous['totalBytes'];

        var bytesPerReq = (requests) ? current['totalBytes']/requests : 0;
        var cpuLoad = current['CPULoad'] || 0;
        if (cpuLoad > 1)
            cpuLoad /= 100;

        console.log('APACHE_REQUESTS %d %s', requests, _param.source);
        console.log('APACHE_BYTES %d %s', current['totalBytes'], _param.source);
        console.log('APACHE_BYTES_PER_REQUEST %d %s', bytesPerReq, _param.source);
        console.log('APACHE_CPU %d %s', cpuLoad, _param.source);
        console.log('APACHE_BUSY_WORKERS %d %s', current['BusyWorkers'], _param.source);
        console.log('APACHE_IDLE_WORKERS %d %s', current['IdleWorkers'], _param.source);
        console.log('APACHE_BUSY_RATIO %d %s', busyRatio, _param.source);

        _previous = current;

        setTimeout(poll, _param.pollInterval);
    });
}

poll();