CentOS Stream 8
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KVM : Install VM Management Tools
2021/03/10
 
Install useful tools for virtual machine management.
[1] Install required packages.
[root@dlp ~]#
dnf -y install libguestfs-tools virt-top
[2] Create a Virtual machine from officially provided images.
# display available OS template

[root@dlp ~]#
virt-builder -l

opensuse-13.1            x86_64     openSUSE 13.1
opensuse-13.2            x86_64     openSUSE 13.2
opensuse-42.1            x86_64     openSUSE Leap 42.1
opensuse-tumbleweed      x86_64     openSUSE Tumbleweed
centos-6                 x86_64     CentOS 6.6
centos-7.0               x86_64     CentOS 7.0
centos-7.1               x86_64     CentOS 7.1
centos-7.2               aarch64    CentOS 7.2 (aarch64)
centos-7.2               x86_64     CentOS 7.2
centos-7.3               x86_64     CentOS 7.3
centos-7.4               x86_64     CentOS 7.4
centos-7.5               x86_64     CentOS 7.5
centos-7.6               x86_64     CentOS 7.6
centos-7.7               x86_64     CentOS 7.7
centos-7.8               x86_64     CentOS 7.8
centos-8.0               x86_64     CentOS 8.0
centos-8.2               x86_64     CentOS 8.2
cirros-0.3.1             x86_64     CirrOS 0.3.1
cirros-0.3.5             x86_64     CirrOS 0.3.5
debian-10                x86_64     Debian 10 (buster)
.....
.....

# create an image of centos-8.2

# replace the [myrootpassword] to the root password you'd like to set

[root@dlp ~]#
virt-builder centos-8.2 --format qcow2 --size 10G -o /var/kvm/images/centos-8.2.qcow2 --root-password password:myrootpassword

[   5.9] Downloading: http://builder.libguestfs.org/centos-8.2.xz
[ 171.8] Planning how to build this image
[ 171.8] Uncompressing
[ 176.8] Resizing (using virt-resize) to expand the disk to 10.0G
[ 217.4] Opening the new disk
[ 223.1] Setting a random seed
[ 223.1] Setting passwords
[ 224.4] Finishing off
                   Output file: /var/kvm/images/centos-8.2.qcow2
                   Output size: 10.0G
                 Output format: qcow2
            Total usable space: 9.3G
                    Free space: 8.0G (85%)

# to create a VM with the image above, run [virt-install]

[root@dlp ~]#
virt-install \
--name centos-8.2 \
--ram 4096 \
--disk path=/var/kvm/images/centos-8.2.qcow2 \
--vcpus 2 \
--os-variant centos8 \
--network bridge=br0 \
--graphics none \
--serial pty \
--console pty \
--boot hd \
--import
[3] [ls] a directory in a virtual machine.
[root@dlp ~]#
virt-ls -l -d centos-st8 /root

total 28
dr-xr-x---.  2 root root  135 Mar  9 05:53 .
dr-xr-xr-x. 17 root root  224 Mar  9 02:40 ..
-rw-------.  1 root root   16 Mar  9 05:53 .bash_history
-rw-r--r--.  1 root root   18 May 11  2019 .bash_logout
-rw-r--r--.  1 root root  176 May 11  2019 .bash_profile
-rw-r--r--.  1 root root  176 May 11  2019 .bashrc
-rw-r--r--.  1 root root  100 May 11  2019 .cshrc
-rw-r--r--.  1 root root  129 May 11  2019 .tcshrc
-rw-------.  1 root root 1310 Mar  9 02:46 anaconda-ks.cfg
[4] [cat] a file in a virtual machine.
[root@dlp ~]#
virt-cat -d centos-st8 /etc/passwd

root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
operator:x:11:0:operator:/root:/sbin/nologin
.....
.....
[5] Edit a file in a virtual machine.
[root@dlp ~]#
virt-edit -d centos-st8 /etc/fstab


#
# /etc/fstab
# Created by anaconda on Tue Mar  9 02:40:07 2021
#
# Accessible filesystems, by reference, are maintained under '/dev/disk/'.
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info.
#
# After editing this file, run 'systemctl daemon-reload' to update systemd
# units generated from this file.
#
/dev/mapper/cs-root     /                       xfs     defaults        0 0
UUID=32d220bc-65a1-4997-83d2-a4a112deba1e /boot xfs     defaults        0 0
/dev/mapper/cs-swap     none                    swap    defaults        0 0
[6] Display disk usage in a virtual machine.
[root@dlp ~]#
virt-df -d centos-st8

Filesystem                           1K-blocks       Used  Available  Use%
centos-st8:/dev/sda1                   1038336     142068     896268   14%
centos-st8:/dev/cs/root               27245572    1883128   25362444    7%
[7] Mount a disk for a virtual machine.
[root@dlp ~]#
guestmount -d centos-st8 -i /media

[root@dlp ~]#
ll /media

total 20
lrwxrwxrwx.   1 root root    7 May 19  2020 bin -> usr/bin
dr-xr-xr-x.   5 root root 4096 Mar  9 11:44 boot
drwxr-xr-x.   2 root root    6 Mar  9 11:40 dev
drwxr-xr-x. 100 root root 8192 Mar  9 14:02 etc
drwxr-xr-x.   3 root root   18 Mar  9 11:45 home
.....
.....
[8] Display the status of virtual machines.
[root@dlp ~]#
virt-top

virt-top 15:59:16 - x86_64 8/8CPU 2593MHz 15830MB
3 domains, 1 active, 1 running, 0 sleeping, 0 paused, 2 inactive D:0 O:0 X:0
CPU: 0.0%  Mem: 768 MB (768 MB by guests)
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