#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# vim: set fileencoding=utf-8
#
# Munin plugin to show amount of memory used by vm
#
# Copyright Maxence Dunnewind, Rodolphe Quiédeville, Adrien Pujol
#
# 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
    '''
    base_config = """graph_title KVM Virtual Machine Memory usage
graph_vlabel Bytes
graph_category virtualization
graph_info This graph shows the current amount of memory used by virtual machines
graph_args --base 1024 -l 0"""
    print(base_config)
    for vm in vm_names:
        print("%s_mem.label %s" % (vm, vm))
        print("%s_mem.type GAUGE" % vm)
        print("%s_mem.draw %s" % (vm, "AREASTACK"))
        print("%s_mem.info memory used by virtual machine %s" % (vm, vm))


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)

    # proxmox uses kvm with -name parameter
    parts = vm_name.split('\x00')
    if (parts[0].endswith('kvm')):
        try:
            return parts[parts.index('-name')+1]
        except ValueError:
            pass

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

def fetch(vms):
    ''' Fetch values for a list of pids
    @param dictionary {kvm_pid: cleaned vm name}
    '''
    res = {}
    for pid in vms:
        try:
            cmdline = open("/proc/%s/cmdline" % pid, "r")
            amount = re.sub(r"^.*-m\x00(.*)\x00-smp.*$",r"\1", cmdline.readline())
            amount = int(amount) * 1024 * 1024
            print("%s_mem.value %s" % (vms[pid], amount))
        except:
            cmdline = open("/proc/%s/cmdline" % pid, "r")
            amount = re.sub(r"^.*-m\x00(\d+).*$",r"\1", cmdline.readline())
            amount = int(amount) * 1024 * 1024
            print("%s_mem.value %s" % (vms[pid], amount))

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 dictionary 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"^.*guest=([a-zA-Z0-9.-_-]*).*$",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 qemu-system-x86_64 kvm", shell=True, stdout=PIPE, text=True)
    return pid.communicate()[0].split()

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()))