Python script to monitor KVM virtual machine CPU, memory, io usage

libvirt-python

Libvirt itself is built on an abstract concept, which provides a common API for commonly used functions of supported hypervisors. Libvirt provides a native layer interface for operating KVM, which can implement basic management operations on virtual machines.

Libvirt-python is a python language binding toolkit based on libvirt API, through which the daily management and monitoring data of VM can be obtained.

We can use python to obtain the monitoring information of the VM by calling the libvirt API

python script

#!/usr/bin/python
# -*- coding: UTF-8 -*-
#author: Ensys Yule
#date: 2019/12/21
#mail: [email protected]
import libvirt
import time
from xml.etree import ElementTree
import os
import commands
import sys
'''将bytes数转换成更加直观的符号显示'''
def bytes2symbols(bytes_value):
 
    '''单位符号'''
    symbols = ('K' ,'M', 'G', 'T', 'P', 'E', 'Z', 'Y')
 
    '''每个单位对应的bytes数的字典,先定义为空'''
    prefix={
    
    }
 
    '''要得到这样的{K:1024, M:1024*1024,G:1024**3},进行for循环'''
    for i,s in enumerate(symbols):
        # '''enumerate()为列举函数'''
        # '''i:代表下标'''
        # '''s:代表改下标对应的值'''
 
        # '''取到符号元组的值,作为prfix字典的key,根据key给value进行赋值'''
        prefix[s]=1024**(i+1)
 
    # '''打印得到的对应字典'''
    # print(prefix)
    symbols_value=0
    symbol=''
    # '''循环prefix字典,得到转换值'''
    for key,value in prefix.items():
        if bytes_value >=value :
            symbols_value=bytes_value/value
            symbol=key
        # 如果不满足最小的KB,则以B显示
        elif bytes_value <1024:
            return  '%0.2fB'%bytes_value
        # '''返回转换值(str)'''
    return  '%0.2f%sB'%(symbols_value,symbol)

while True: 
    os.system('clear')
    conn = libvirt.open("qemu:///system")
    print '''
*********************************************
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\  =  /O
               ____/`---'\____
             .'  \\|     |//  `.
            /  \\|||  :  |||//  \
           /  _||||| -:- |||||-  \
           |   | \\\  -  /// |   |
           | \_|  ''\---/''  |   |
           \  .-\__  `-`  ___/-. /
         ___`. .'  /--.--\  `. . __
      ."" '<  `.___\_<|>_/___.'  >'"".
     | | :  `- \`.;`\ _ /`;.`/ - ` : | |
     \  \ `-.   \_ __\ /__ _/   .-` /  /
======`-.____`-.___\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
           佛祖保佑       永不宕机'''
    print '\033[0;37;41m%s\033[0m'%'\n\n######################     实时监控kvm虚拟机信息--CPU,内存，磁盘I/O    ##################'
    print '\n作者：黄宇轩'
    print '时间: 2019/12/21'
    print 'Ctrl+C 可退出程序,脚本每6秒执行一次'
    if len(conn.listDomainsID()) <= 0 :
        print '\033[0;37;41m%s\033[0m'%'没有正在运行的虚拟机，程序退出.'
        os.system('command')
        time.sleep(1)
        sys.exit()
    try:
        for id in reversed(conn.listDomainsID()):
            print '\n'
            domain = conn.lookupByID(id)
            print '实例名：'+'\033[0;37;44m%s\033[0m'%domain.name() + '\n'
            print '状态：'+'\033[0;37;42m%s\033[0m'%'开机' if domain.info()[0]==1 else '\033[0;37;41m%s\033[0m'%'关机',
            print '最大内存：' + (str)(domain.info()[1]/1024) + 'Mb',
            print 'CPU数量：' + (str)(domain.info()[3]),
            print 'CPU时间：' + (str)(domain.info()[4])

            #开始计算虚拟机内存
            domain.setMemoryStatsPeriod(10)
            meminfo = domain.memoryStats()
            free_mem = float(meminfo['unused'])
            total_mem = float(meminfo['available'])
            util_mem = ((total_mem-free_mem) / total_mem)*100
            print ('内存已使用：' + str(util_mem)) + '%'

            #开始计算磁盘I/O
            tree = ElementTree.fromstring(domain.XMLDesc())
            devices = tree.findall('devices/disk/target')
            for d in devices:
                device = d.get('dev')
                try:
                    devstats = domain.blockStats(device)
                    print '磁盘设备：'+(device,devstats)[0],
                    read_bytes = bytes2symbols((device,devstats)[1][0])
                    write_bytes = bytes2symbols((device,devstats)[1][2])

                    print('读:%10s'%read_bytes),
                    print '读取请求：' + (str)((device,devstats)[1][1])+ '次',
                    print('写:%10s'%read_bytes),
                    print '写入请求：' + (str)((device,devstats)[1][3])+ '次'
                except libvirt.libvirtError:
                    pass
            
            #开始计算cpu使用率
            t1 = time.time()
            c1 = int (domain.info()[4])
            time.sleep(0.05);
            t2 = time.time();
            c2 = int (domain.info()[4])
            c_nums = int (domain.info()[3])
            usage = (c2-c1)*100/((t2-t1)*c_nums*1e9)
            print ("CPU 已使用：" + (str)(usage)) + '%'
    except: 
        pass
    os.system('command')
    time.sleep(6)

Instructions

[root@localhost ~]# python -V
Python 2.7.5
[root@localhost ~]# vim kvm_monitor.py 
[root@localhost ~]# python kvm_monitor.py 

operation result

References

• Obtain the monitoring information of the kvm virtual machine through python (based on libvirt API): https://blog.51cto.com/10616534/1878609

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