monitor_server

#!/usr/bin/env python
import sys
import re
import os
import boto.ec2
from boto.utils import get_instance_metadata
import ConfigParser

# Configuration file is required in the same directory as this program
oConfig = ConfigParser.RawConfigParser()
sConfigPath = os.path.dirname(os.path.realpath(sys.argv[0])) + '/config.ini'
if os.path.isfile(sConfigPath) == False:
    sys.exit('Missing configuration file: ' + sConfigPath)
oConfig.read(sConfigPath)

# Get the configuration elements
AWS_ACCESS_ID     = oConfig.get('cloudwatch', 'access_id')
AWS_SECRET_KEY    = oConfig.get('cloudwatch', 'secret_key')
METRICS_NAMESPACE = oConfig.get('cloudwatch', 'namespace')
MONITOR_DISKS     = oConfig.items('disk-metrics')
RAM_METRIC        = oConfig.get('memory-metrics', 'ram-metric')
SWAP_METRIC       = oConfig.get('memory-metrics', 'swap-metric')


def getDiskUsage(sPath):
    """Return disk-usage percentage for a given directory"""
    oStat  = os.statvfs(sPath)
    iTotal = (oStat.f_blocks * oStat.f_frsize)
    iUsed  = (oStat.f_blocks - oStat.f_bfree) * oStat.f_frsize
    try:
        fPercent = (float(iUsed) / iTotal) * 100
    except ZeroDivisionError:
        fPercent = 0
    return round(fPercent, 1)


def getAllDiskUsage(aDiskConfig):
    """Get the disk usage for multiple directories"""
    aUsage = []
    for aDisk in aDiskConfig:
        sName, sDir = aDisk
        iUsage = getDiskUsage(sDir)
        aUsage.append((sName, sDir, iUsage))
    return aUsage


def collectMemoryUsage():
    """Return the memory usage for the current server"""
    aMemInfo = {}
    rePattern = re.compile('([\w\(\)]+):\s*(\d+)(:?\s*(\w+))?')
    with open('/proc/meminfo') as fp:
        for sLine in fp:
            match = rePattern.match(sLine)
            if match:
                aMemInfo[match.group(1)] = float(match.group(2))
    return aMemInfo


def sendMetrics(oBoto, sInstanceId, aMetrics, sNameSpace, sUnit):
    """Send metrics to CloudWatch - Metrics are sent in key-value pairs"""
    aKeys   = aMetrics.keys()
    aValues = aMetrics.values()
    print "Setting metric - namespace:%s  server:%s  name:%s  value:%s  unit:%s" % \
        (sNameSpace, sInstanceId, aKeys[0], aValues[0], sUnit)
    oBoto.put_metric_data(sNameSpace, aKeys, aValues, unit=sUnit, dimensions={"InstanceId": sInstanceId})


def getBoto (sAccessId, sSecretKey):
    """"Get the Boto connection, using the default role if the ID and Key are not set"""
    if re.search('\w', sAccessId) and re.search('\w', sSecretKey):
        oBoto = boto.connect_cloudwatch(aws_access_key_id=sAccessId, aws_secret_access_key=sSecretKey)
    else:
        oBoto = boto.connect_cloudwatch()
    return oBoto


def getMemoryUsage(sRamMetric, sSwapMetric):
    """Get the memory usage for the server"""
    
    aMemInfo = collectMemoryUsage()

    # Total free memory = free + buffers + cached
    iMemFree = aMemInfo['MemFree'] + aMemInfo['Buffers'] + aMemInfo['Cached']
    iMemUsed = aMemInfo['MemTotal'] - iMemFree
    
    if aMemInfo['SwapTotal'] != 0 :
        iSwapUsed    = aMemInfo['SwapTotal'] - aMemInfo['SwapFree'] - aMemInfo['SwapCached']
        fSwapPercent = iSwapUsed / aMemInfo['SwapTotal'] * 100
    else:
        fSwapPercent = 0.0

    return [ ('memory-ram-usage', round (iMemUsed / aMemInfo['MemTotal'] * 100, 1)),
             ('memory-swap-usage', round(fSwapPercent, 1)) ]


def getInstanceId():
    """Get the instance ID for the current server"""
    aMetaData = get_instance_metadata()
    return aMetaData['instance-id']


# Primary execution
if __name__ == '__main__':

    sInstanceId = getInstanceId()
    oBoto       = getBoto(AWS_ACCESS_ID, AWS_SECRET_KEY)

    for aUsage in getAllDiskUsage(MONITOR_DISKS):
        sMetricName, sDir, fPercent = aUsage
        print "Disk usage -   %-25s percentage: %0.1f%%   directory: %s" % (sMetricName, fPercent, sDir)
        sendMetrics(oBoto, sInstanceId, { sMetricName: fPercent }, METRICS_NAMESPACE, 'Percent')

    for aUsage in getMemoryUsage(RAM_METRIC, SWAP_METRIC):
        sMetricName, fPercent = aUsage
        print "Memory usage - %-25s percentage: %0.1f%%" % (sMetricName, fPercent)
        sendMetrics(oBoto, sInstanceId, { sMetricName: fPercent }, METRICS_NAMESPACE, 'Percent')