#!/usr/bin/python
# -*- coding: utf-8 -*-
# vim: set fileencoding=utf-8
#
# Munin plugin to show CPU used by vm
#
# Copyright Maxence Dunnewind, Rodolphe Quiédeville
#
# License : GPLv3
#
# parsed environment variables:
# vmsuffix: part of vm name to be removed
#
#%# capabilities=autoconf
#%# family=contrib

import re, os, sys
from subprocess import Popen, PIPE

def config(vm_names):
    ''' Print the plugin's config
    @param vm_names : a list of "cleaned" vms' name
    '''
    percent = len(filter(lambda x: x[0:3] == 'cpu' and x[3] != ' ', open('/proc/stat', 'r').readlines())) * 100

    base_config = """graph_title KVM Virtual Machine CPU usage
graph_vlabel %%
graph_category KVM
graph_scale no
graph_period second
graph_info This graph shows the current CPU used by virtual machines
graph_args --base 1000 -r --lower-limit 0 --upper-limit %d""" % percent
    print base_config
    draw = "AREA"
    for vm in vm_names:
        print "%s_cpu.label %s" % (vm, vm)
        print "%s_cpu.min 0" % vm
        print "%s_cpu.type DERIVE" % vm
        print "%s_cpu.draw %s" % (vm, draw)
        print "%s_cpu.info percent of cpu time used by virtual machine" % vm
	draw = "STACK"


def clean_vm_name(vm_name):
    ''' Replace all special chars
    @param vm_name : a vm's name
    @return cleaned vm's name
    '''

    # suffix part defined in conf
    suffix = os.getenv('vmsuffix')
    if suffix:
        vm_name = re.sub(suffix,'',vm_name)

    return re.sub(r"[^a-zA-Z0-9_]", "_", vm_name)

def detect_kvm():
    ''' Check if kvm is installed
    '''
    kvm = Popen("which kvm", shell=True, stdout=PIPE)
    kvm.communicate()
    return not bool(kvm.returncode)

def find_vm_names(pids):
    '''Find and clean vm names from pids
    @return a dictionnary of {pids : cleaned vm name}
    '''
    result = {}
    for pid in pids:
        cmdline = open("/proc/%s/cmdline" % pid, "r")
        result[pid] = clean_vm_name(re.sub(r"^.*-name\x00([a-zA-Z0-9.-]*)\x00\-.*$",r"\1", cmdline.readline()))
    return result
    
def list_pids():
    ''' Find the pid of kvm processes
    @return a list of pids from running kvm
    '''
    pid = Popen("pidof qemu-kvm kvm", shell=True, stdout=PIPE)
    return pid.communicate()[0].split()

def fetch(vms):
    ''' Fetch values for a list of pids
    @param dictionnary {kvm_pid: cleaned vm name}
    '''
    for ( pid, name ) in vms.iteritems():
        ( user, system ) = open("/proc/%s/stat" % pid, 'r').readline().split(' ')[13:15]
        print '%s_cpu.value %d' % ( name, int(user) + int(system) )
        
if __name__ == "__main__":
    if len(sys.argv) > 1:
        if sys.argv[1] in ['autoconf', 'detect']:
            if detect_kvm():
                print "yes"
            else:
                print "no"
        elif sys.argv[1] == "config":
            config(find_vm_names(list_pids()).values())
        else:
            fetch(find_vm_names(list_pids()))
    else:
        fetch(find_vm_names(list_pids()))