KVM : Create Virtual Machine2019/10/08

	Install GuestOS and Create a Virtual Machine. This example shows to create VM with installing CentOS 8.
[1]	Install GuestOS on text mode, it's OK on console or remote connection with Putty and so on. Furthermore, Virtual Machine's images are placed at [/var/lib/libvirt/images] by default as a Storage Pool, but this example shows to create and use a new Storage Pool.(use any place you like)

# create a Storage Pool directory

[root@dlp ~]#

mkdir -p /var/kvm/images

[root@dlp ~]#

virt-install \

--name centos8 \
--ram 4096 \
--disk path=/var/kvm/images/centos8.img,size=30 \
--vcpus 2 \
--os-type linux \
--os-variant rhel8.0 \
--network bridge=br0 \
--graphics none \
--console pty,target_type=serial \
--location 'https://ftp.riken.jp/Linux/centos/8/BaseOS/x86_64/os/' \
--extra-args 'console=ttyS0,115200n8 serial'

Starting install...

# installation starts

The example of options above means like follows. There are many options for others, make sure with [man virt-install].

--name

specify the name of Virtual Machine

--ram

specify the amount of memory of Virtual Machine

--disk path=xxx ,size=xxx

[path=] specify the location of disks of Virtual Machine (default is [/var/lib/libvirt/images])
[size=] specify the amount of disk of Virtual Machine

--vcpus

specify the virtual CPUs

--os-type

specify the type of GuestOS

--os-variant

specify the kind of GuestOS
possible to show the list of OS with follows
[# osinfo-query os]

--network

specify network type of Virtual Machine

--graphics

specify the kind of graphics. if set [none], it means nographics

--console

specify the console type

--location

specify the location of installation source where from

--extra-args

specify parameters that are set in Kernel

[2]	For installing on text mode, it's the same with common procedure of installation. After finishing installation, restart computer and then login prompt is shown like follwos.

CentOS Linux 8 (Core)
Kernel 4.18.0-80.7.1.el8_0.x86_64 on an x86_64

Activate the web console with: systemctl enable --now cockpit.socket

localhost login:

[3]	Move to GuestOS to HostOS with Ctrl + ] key. Move to HostOS to GuestOS with a command [virsh console (name of virtual machine)].

[root@localhost ~]#

# Ctrl + ] key

[root@dlp ~]#

# Host's console

[root@dlp ~]#

virsh console centos8

# switch to Guest's console

Connected to domain centos8

Escape character is ^]

# Enter key

[root@localhost ~]#

# Guest's console

[4]	It's easy to replicate a copy VM from current VM with a command below.

[root@dlp ~]#

virt-clone --original centos8 --name template --file /var/kvm/images/template.img

Allocating 'template.img'                                   |  30 GB  00:02

Clone 'template' created successfully.

# disk image

[root@dlp ~]#

ll /var/kvm/images/template.img

-rw-------. 1 root root 1875443712 Oct 7 19:41 /var/kvm/images/template.img

# configuration file

[root@dlp ~]#

ll /etc/libvirt/qemu/template.xml

-rw-------. 1 root root 4744 Oct 7 19:41 /etc/libvirt/qemu/template.xml

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