How to Deploy KVM Virtualization on CentOS 7 with a Web Management Interface

Virtualization Overview

Virtualization creates multiple logical computers on a single physical machine, allowing each logical computer to run a different operating system. It expands hardware capacity, enables multiple OSes to share resources, and isolates applications so they do not interfere with each other.

Why Enterprises Use Virtualization

Enterprises adopt virtualization to save costs and improve efficiency. The physical host provides hardware resources to guest virtual machines through a hypervisor, a software layer between hardware and the OS. Hypervisors come in two types: full virtualization (no kernel modification required) and para‑virtualization (requires kernel changes).

KVM Introduction

KVM (Kernel‑Based Virtual Machine) is implemented as a Linux kernel module kvm.ko that manages virtual CPU and memory. I/O virtualization (storage, network) is handled by QEMU, a pure‑software emulator that translates virtual device operations to real hardware. Together, KVM provides hardware‑assisted CPU/memory virtualization while QEMU handles device emulation.

KVM Deployment (CentOS 7)

Environment: CentOS 7, IP 192.168.222.140.

Enable CPU virtualization in the BIOS (or shut down the VM to enable it).

Configure a new VM with 8 GB RAM, 80 GB disk, and enable virtualization.

# lsblk // view partitions

# parted /dev/sdb

# mkfs.xfs /dev/sdb1

# mkdir /kvmdata

# vim /etc/fstab

UUID="09888ad8-a1ef-42fb-9c36-937e071bf897"  /kvmdata   xfs  defaults 0 0

# mount -a

Disable firewall and SELinux, then reboot:

# systemctl stop firewalld

# setenforce 0

# systemctl disable --now firewalld

# reboot

Configure YUM repository (Aliyun mirror) and install required packages:

# rm -rf /etc/yum.repos.d/*

# curl -o /etc/yum.repos.d/CentOS-Base.repo https://mirrors.aliyun.com/repo/Centos-7.repo

# yum -y install epel-release wget net-tools unzip zip gcc gcc-c++

Verify CPU supports KVM: # egrep -o 'vmx|svm' /proc/cpuinfo Install KVM and related packages:

# yum -y install qemu-kvm qemu-kvm-tools qemu-img virt-manager libvirt libvirt-python libvirt-client virt-install virt-viewer bridge-utils libguestfs-tools

Configure network bridge (br0) to place VMs on the same LAN as the host:

# cp ifcfg-ens33 ifcfg-br0

# vim ifcfg-br0

TYPE=bridge
BOOTPROTO=none
NAME=br0
DEVICE=br0
ONBOOT=yes
IPADDR=192.168.222.140
PREFIX=24
GATEWAY=192.168.222.2
DNS1=192.168.222.2

# vim ifcfg-ens33

TYPE=Ethernet
BOOTPROTO=none
NAME=ens33
DEVICE=ens33
ONBOOT=yes
BRIDGE=br0

# systemctl restart NetworkManager

Enable and start libvirtd: # systemctl enable --now libvirtd Verify KVM modules are loaded: # lsmod | grep kvm Create a symlink for the qemu-kvm command:

# ln -s /usr/libexec/qemu-kvm /usr/bin/qemu-kvm

KVM Web Management Interface Installation

Install dependencies for webvirtmgr:

# yum -y install git python-pip libvirt-python libxml2-python python-websockify supervisor nginx python-devel

Map GitHub domain if needed:

# vim /etc/hosts

20.205.243.166 github.com

Clone the webvirtmgr source code and install Python requirements:

# cd /usr/local/src/

# git clone http://github.com/retspen/webvirtmgr.git

# cd webvirtmgr

# pip install -r requirements.txt

Initialize the Django database and create a superuser: # python manage.py syncdb Copy web files to /var/www and set ownership:

# mkdir /var/www

# cp -r /usr/local/src/webvirtmgr/ /var/www/

# chown -R nginx.nginx /var/www/webvirtmgr/

Configure Gunicorn to bind to localhost:8000:

# vim /var/www/webvirtmgr/conf/gunicorn.conf.py

bind = '127.0.0.1:8000'
backlog = 2048

Configure Nginx as a reverse proxy:

# cp /etc/nginx/nginx.conf /etc/nginx/nginx.conf.bak

# vim /etc/nginx/nginx.conf

user nginx;
worker_processes auto;
error_log /var/log/nginx/error.log;
pid /run/nginx.pid;
worker_rlimit_nofile 655350;

# vim /etc/nginx/conf.d/webvirtmgr.conf

server {
    listen 80 default_server;
    server_name localhost;
    location /static/ {
        root /var/www/webvirtmgr/webvirtmgr;
        expires max;
    }
    location / {
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $host:$server_port;
        proxy_set_header X-Forwarded-Proto $remote_addr;
        proxy_connect_timeout 600;
        proxy_read_timeout 600;
        proxy_send_timeout 600;
        client_max_body_size 1024M;
    }
}

Configure Supervisor to manage Gunicorn and the console service:

# vim /etc/supervisord.conf

[program:webvirtmgr]
command=/usr/bin/python2 /var/www/webvirtmgr/manage.py run_gunicorn -c /var/www/webvirtmgr/conf/gunicorn.conf.py
directory=/var/www/webvirtmgr
autostart=true
autorestart=true
logfile=/var/log/supervisor/webvirtmgr.log
log_stderr=true
user=nginx

[program:webvirtmgr-console]
command=/usr/bin/python2 /var/www/webvirtmgr/console/webvirtmgr-console
directory=/var/www/webvirtmgr
autostart=true
autorestart=true
stdout_logfile=/var/log/supervisor/webvirtmgr-console.log
redirect_stderr=true
user=nginx

Enable and start services:

# systemctl enable --now nginx

# systemctl enable --now libvirtd

# systemctl enable --now supervisord.service

KVM Web Interface Management

Access the web UI via a browser (e.g., http://<host_ip>/), log in with the superuser created earlier, add a connection to the local KVM host, create storage pools, upload ISO images, define networks, and launch new virtual machines using the graphical wizard.

Typical steps in the UI include:

Creating a storage pool pointing to /kvmdata.

Uploading an OS ISO (e.g., CentOS‑7‑x86_64‑DVD‑1708.iso).

Defining a virtual network (bridge mode).

Launching a new VM with desired CPU, memory, and disk settings.

Troubleshooting

If cloning the repository fails due to network restrictions, configure proxy settings or update the /etc/hosts entry for GitHub. Verify that the Git configuration does not contain invalid proxy entries.