System of test development - create test virtual machine on demand

First , Let's get to know KVM Several concepts and tools related to virtual machine .

• kvm： Virtual machine based on Kernel （ engine ）
• qemu： Used to simulate virtual machines IO equipment
• qemu-img： Virtual machine disk management tool
• libvirt： Of virtualization services API Interface
• virsh： be based on libvirt Implementation of the command line tool
• qemu-manager： Graphical management tools

newly build KVM When virtual machines , You can specify another disk file as BackingFile.BackingFile Is a read-only virtual disk base image , It can be shared among multiple virtual machines . be based on BackingFile When creating and running a virtual machine , Only write files incrementally to your own disk file , To improve efficiency 、 Save disk and maintenance costs .

The virtual machine snapshot saves the state of the virtual machine at a specified point in time , When we encounter problems or errors in automated testing , Snapshots can be used to save 、 And restore to a certain point in time . With the help of BackingFile Mechanism , Virtual machines support multi-layer dependent snapshot chains like the following .

base image <-- vm01 <-- snap 1 <-- snap 2 <-- vm02(active)

You can use the following command , A virtual machine in the snapshot chain , Export to form a separate disk image file , It no longer depends on other images .

qemu-img convert -O qcow2 vm02.qcow2 vm-templ.img

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Suppose we are in the user's working directory , The following directory has been established .

• kvm        root directory
• iso       Store CD image
• base      Deposit BackingFile
• share     Store the shared disk image , User storage test tool 、 Drive, etc
• image     The disk image of the test machine xml Store exported virtual machine XML The configuration file

Here's an example , Introduce to you the method of quickly creating and testing virtual machines .

• according to Last article Step in , Create a Win10 virtual machine ;
• In virtual machine , Install the test software used in the work ;
• Use the following command , Create a new shared tool disk ;

qemu-img create -f qcow2 -o cluster_size=2M kvm/share/tools.qcow2 10G

• Mount the shared disk to the virtual machine , Copy tools and files to this disk ;
• Remove the virtual machine , In the confirmation dialog , Please choose not to delete the relevant disk files ;
• Move the primary disk file of the original virtual machine to the basic image directory , Such as kvm/base/windows/win10/x64-pro-zh_cn.qcow2
• Execute the following command , Take the above basic image as BackingFile, Create a new virtual machine disk ;

qemu-img create -f qcow2 -o cluster_size=2M,backing_file=kvm/base/windows/win10/x64-pro-zh_cn.qcow2 kvm/image/test-win10-x64-pro-zh_cn-01.qcow2 40G

• In the graphical interface , Create a new test virtual machine , Hang on the newly created virtual machine and shared disk .

In addition to using a graphical interface qemu-manager Software , A command line method is also provided here , You can use it in the code of the test platform .

• Export virtual machine XML The configuration file

virsh dumpxml test-win10-x64-pro-zh > kvm/xml/test-win10-x64-pro-zh.xml

• modify XML The following fields in the configuration file ：

name uuid vcpu memory and currentMemory mac address The first 1 block disk Of source file

• In the 1 block disk Of Elemnt in , Add the following BackingFile About .

<backingStore type="file" index="2">
  <format type="qcow2"/>
  <source file="/home/aaron/kvm/base/windows/win10/x64-pro-zh_cn.qcow2"/>
<backingStore/>

• If necessary, use the page VNC Access the virtual desktop , find XML Of graphics Elements , Change it to the following .

<graphics type="vnc" port="-1" autoport="yes" listen="0.0.0.0" passwd="P2ssw0rd">
  <listen type="address" address="0.0.0.0"/>
</graphics>

• Use the following command to define the virtual machine .

virsh define kvm/xml/test-win10-x64-pro-zh.xml

• Start the virtual machine with the following command .

virsh start test-win10-x64-pro-zh

• Use the following command to get the name of the virtual machine VNC Port number , stay VNC Use... In software ”5900+ The number “ The port of , Access the virtual machine remote desktop .

virsh vncdisplay test-win10-x64-pro-zh

in addition , I use GO Language based on libvirt Functions related to virtual machine management of interface , This open source project aims to provide you with a platform based on KVM Virtual machine and Docker Container of 、 On demand test environment management platform , Please refer to the website for details https://github.com/easysoft/zagent .

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Common commands ：

#  View virtual machine information 
qemu-img info --backing-chain kvm/image/test-win10-x64-pro-zh_cn-01.qcow2
#  Modify the virtual machine disk size 
qemu-img resize x64-pro-zh_cn.qcow2 +10G
#  View the list in the virtual machine 
virsh list --all
#  View virtual machine VNC port 
virsh vncdisplay win10-test
#  Export virtual machine XML The configuration file 
virsh dumpxml win10-test > win10-test.xml
#  Create a virtual machine disk image 
qemu-img create -f qcow2 -o cluster_size=2M,backing_file=base.qcow2 win10-test.qcow2 40G
#  Definition 、 Undefine , start-up 、 Stop the virtual machine 
virsh define win10-test.xml
virsh start win10-test
virsh destroy win10-test
virsh undefine win10-test