Nuage VSC – Modify QCOW2 images with guestfish

Hi there,

This post is useful to anyone planing to use guestfish to make some changes to any qcow2 disk image file. You can solve issues like change user settings, or define static ip addresses, or change grub settings.

I am using guestfish to change some configurations into my vsc_singledisk.qcow2 image. Why? because all the changes into VSC must be done thru a console. However, If you are thinking to run this on OpenStack liberty/kvm. It would be a issue. Most of the instances has been managed thru vnc (graphics). Then, I’ve added network settings to bof.cfg file to make this instance boot with a specific ip address. I can follow the next steps of its setup thru ssh 😉

Install your guestfish and libvirtd packages

I’ve downloaded a centos7 minimal OVA file to my Mac. I’ve imported it to my vbox and make run. I’ve used to have selinux disabled. Maybe you will need to change it to permissible.

First of all you have to install kvm and the guestfish. Then, you will have to disbale NetworManager and firewalld. Restart the libvirtd and set LIBGUESTFS_BACKEND=direct. I’ve copied my qcow2 file thru scp previously. You will have to change the ownership to qemu:qemu to this file to make it work.

[root@jumbox ~]# yum install -y qemu-kvm libvirt libvirt-python libguestfs-tools virt-install
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: bay.uchicago.edu
 * extras: centos-distro.cavecreek.net
 * updates: centos.mia.host-engine.com
#
# many boring lines
# many boring lines
#

Installed:
  libguestfs-tools.noarch 1:1.28.1-1.55.el7.centos.2        libvirt.x86_64 0:1.2.17-13.el7_2.4        qemu-kvm.x86_64 10:1.5.3-105.el7_2.4       
  virt-install.noarch 0:1.2.1-8.el7                        

Dependency Installed:
  libguestfs.x86_64 1:1.28.1-1.55.el7.centos.2                        libguestfs-tools-c.x86_64 1:1.28.1-1.55.el7.centos.2                      
  libvirt-daemon-kvm.x86_64 0:1.2.17-13.el7_2.4                       perl-Sys-Guestfs.x86_64 1:1.28.1-1.55.el7.centos.2                        
  perl-Sys-Virt.x86_64 0:1.2.17-2.el7                                 perl-libintl.x86_64 0:1.20-12.el7                                         

Complete!
[root@jumbox ~]# yum -y install guestfish
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: bay.uchicago.edu
 * extras: centos-distro.cavecreek.net
 * updates: centos.mia.host-engine.com
#
# many boring lines
# many boring lines
#
Installed:
  libguestfs-tools-c.x86_64 1:1.28.1-1.55.el7.centos.2                                                                                           

Complete!
[root@jumbox ~]# systemctl stop NetworkManager
[root@jumbox ~]# systemctl disable NetworkManager
Removed symlink /etc/systemd/system/multi-user.target.wants/NetworkManager.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.NetworkManager.service.
Removed symlink /etc/systemd/system/dbus-org.freedesktop.nm-dispatcher.service.
[root@jumbox ~]# systemctl start network
[root@jumbox ~]# systemctl stop firewalld
[root@jumbox ~]# systemctl disable firewalld
Removed symlink /etc/systemd/system/dbus-org.fedoraproject.FirewallD1.service.
Removed symlink /etc/systemd/system/basic.target.wants/firewalld.service.
[root@jumbox ~]# service libvirtd restart
Redirecting to /bin/systemctl restart  libvirtd.service
[root@jumbox ~]# virsh
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # list
 Id    Name                           State
----------------------------------------------------

virsh # exit
[root@jumbox ~]# chown qemu:qemu vsc_singledisk.qcow2 
[root@jumbox ~]# export LIBGUESTFS_BACKEND=direct

Modify your files into your qcow2 image thru guestfish

Next lines will show you how to modify the qcow2 image file. This case I am modifying bof.cfg file at the root folder.

[root@jumbox ~]# mv vsc_singledisk.qcow2 vsc_singledisk_dhcp.qcow2 
[root@jumbox ~]# guestfish --rw -a vsc_singledisk_dhcp.qcow2 

Welcome to guestfish, the guest filesystem shell for
editing virtual machine filesystems and disk images.

Type: 'help' for help on commands
      'man' to read the manual
      'quit' to quit the shell

> run
 100% ⟦▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒▒⟧ 00:00
> mount /dev/sda1 /
> ls /
bof.cfg
config.cfg
nvram.dat
syslinux
timos
> vi /bof.cfg
> exit

The bof.cfg file that I’ve found is this:

primary-image        cf1:/timos/cpm.tim
primary-config       cf1:/config.cfg
autonegotiate
duplex               full
speed                100
wait                 3
persist              off
console-speed        115200

And this is how I’ve left it.

primary-image    cf1:\timos\cpm.tim
primary-config   cf1:\config.cfg
ip-address-dhcp
primary-dns      192.168.101.3
dns-domain       nuage.lab
static-route     0.0.0.0/1 next-hop 192.168.101.1
autonegotiate
duplex           full
speed            100
wait             3
persist          off
no li-local-save
no li-separate
console-speed    115200

See ya!