KVM : Create Virtual Machines2021/11/10

	Install GuestOS and Create a Virtual Machine. This example shows to create VM with installing Fedora 35.
[1]	On this example, Download an ISO file of Fedora on a directory first and Install GuestOS from the ISO on the text mode. It's OK on the console or remote connection via SSH 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 fedora35 \
--ram 4096 \
--disk path=/var/kvm/images/fedora35.img,size=20 \
--vcpus 2 \
--os-variant fedora34 \
--network bridge=br0 \
--graphics none \
--console pty,target_type=serial \
--location /home/Fedora-Server-dvd-x86_64-35-1.2.iso \
--extra-args 'console=ttyS0,115200n8 serial' 

Starting install...   # installation starts
.....
.....

# after this, installation proceeds with the common procedure

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=xxx] : specify the location of disks of Virtual Machine (default is [/var/lib/libvirt/images]) [size=xxx] : specify the amount of disk of Virtual Machine
--vcpus	specify the virtual CPUs
--os-variant	specify the kind of GuestOS possible to show the list of available OS with the command below [# osinfo-query os]
--network	specify network type of Virtual Machine
--graphics	specify the kind of graphics possible to specify spice, vnc, none and so on
--console	specify the console type
--location	specify the location of installation source where from
--extra-args	specify parameters that are set in Kernel

[2]	After finishing installation, restart computer and then login prompt is shown like follwos.

Fedora Linux 35 (Server Edition)
Kernel 5.14.10-300.fc35.x86_64 on an x86_64 (ttyS0)

Web console: https://fedora:9090/ or https://10.0.0.211:9090/

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 fedora35    # switch to Guest's console
Connected to domain fedora35

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 fedora35 --name template --file /var/kvm/images/template.img

Allocating 'template.img'                                   |  20 GB  00:03

Clone 'template' created successfully.

# disk image

[root@dlp ~]#

ll /var/kvm/images/template.img

-rw-------. 1 root root 1804009472 Nov 10 09:00 /var/kvm/images/template.img

# configuration file

[root@dlp ~]#

ll /etc/libvirt/qemu/template.xml

-rw-------. 1 root root 4963 Nov 10 09:00 /etc/libvirt/qemu/template.xml

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