用C++编程调用libvirt的API来创建KVM虚拟机

1. 如果已经写好了创建kvm的配置文件（stand.xml）格式，那么创建kvm虚拟机只要使用命令即可：virsh define ./conf/stand.xml
virsh start rheltest3相关阅读：使用 libvirt创建和管理KVM虚拟机 http://www.linuxidc.com/Linux/2012-06/62934.htm应用Libvirt连接KVM虚拟化平台 http://www.linuxidc.com/Linux/2013-02/79939.htmUbuntu下用libvirt安装KVM虚拟机时找不到/bin/qemu-kvm问题解决 http://www.linuxidc.com/Linux/2013-08/88985.htm2. 如果直接编程调用libvirt创建kvm虚拟机，则可用以下程序/***************************************************************************
* create_vm.cpp
* create kvm machine（domain） based on conf.xml
* the first parameter is the conf xml files" name
* Note: the .xml must has two boot types （cdrom/hd） by any order
* compile command: "g++ create_vm.cpp -o createvm -lvirt"
* running command: "./createvm /path/to/xml/example.xml"
* author : Aborn Jiang
* date : Aug.17, 2013
* version : v0.1
***************************************************************************/#include <iostream>
#include <cstdio>
#include <string>
#include <fstream>
#include <sstream>
#include <libvirt/libvirt.h>
#include <libvirt/virterror.h>
#include <memory.h>using namespace std;
int main（int argc, char* argv[]）
{
if （ 1 == argc ） {
cout << "must and only need an argument, this is, configure .xml file name." << endl;
return -1;
}
if （ 3 <= argc ） {
cout << "too many arguments. must and only need one, that is, .xml file name." << endl;
return -1;
}
string xmlfile=argv[1];
cout << "*************************" << endl;
cout << "begin to build vm ..." << endl;
cout << "xmlfile path:" << xmlfile <<endl;

ifstream file（xmlfile.c_str（））;
if （！file） {
cout << "Cannot open file, permission denied." << xmlfile << endl;
return -1;
}
stringstream buffer;
buffer << file.rdbuf（）;
string xmlcontents = buffer.str（）;
file.close（）;

/*************************************************************************************
* deal with the original xml configuration file
* initxmlconts for transient guest domain（install os） configure （boot from cdrom）
* xmlcontents for persistent guest domain configure （boot from hd）
************************************************************************************/
int pos_boot = xmlcontents.find（"boot"）;
int pos_hd = xmlcontents.find（"hd", pos_boot）;
int pos_cdrom = xmlcontents.find（"cdrom", pos_boot）;
cout << "pos_hd=" << pos_hd << " pos_cdrom=" << pos_cdrom << endl;
string initxmlconts（xmlcontents）;
if （ pos_hd > pos_cdrom ） { // cdrom apears in first order
cout << "cdrom apears in first order" << endl;
xmlcontents.replace（pos_cdrom, 5 ,"hd"）;
pos_hd=xmlcontents.find（"hd", pos_cdrom + 2）;
xmlcontents.replace（pos_hd, 2, "cdrom"）;
} else { // hd apears in first order
cout << "hd apears in first order" << endl;
initxmlconts.replace（pos_hd, 2, "cdrom"）;
pos_cdrom=initxmlconts.find（"cdrom", pos_hd + 5）;
initxmlconts.replace（pos_cdrom, 5, "hd"）;
} // create and boot a transient initial domain, for vm os installation
virConnectPtr conn = virConnectOpen（"qemu:///system"）;
if （NULL == conn ） {
virErrorPtr error = virGetLastError（）;
cout << error->message << endl;
return -1;
}
virDomainPtr vmpi = virDomainCreateXML（conn, initxmlconts.c_str（）, VIR_DOMAIN_START_AUTODESTROY）;
if （NULL == vmpi） {
virErrorPtr error = virGetLastError（）;
cout << error->message << endl;
return -1;
}
cout << "os installation ongoing, it will spend some time..." << endl;
while （ 1 == virDomainIsActive（vmpi））; // waiting until installation finish.
cout << "os installation finished..." << endl;
if （NULL == conn）
virConnectPtr conn = virConnectOpen（"qemu:///system"）;
cout << "start boot the vm machine..." << endl; // store xmlcontents configuration for a persistent guest domain and boot it.
virDomainPtr vmp = virDomainDefineXML（conn, xmlcontents.c_str（））;
if （NULL == vmp） {
virErrorPtr error = virGetLastError（）;
cout << error->message << endl;
return -1;
} else {
cout << "define persistent domain success." << endl;
if （virDomainCreate（vmp） < 0） { // boot the vm.
cout << "Unable to boot guest configuration." << endl;
} else {
cout << "Boot the persistent defined guest ..." << endl;
}
cout << "build vm finished." << endl;
cout << "*************************" << endl;
return 0;
}
}