Linux VDA – Post build tasks and Linux VDA 1912 preparation

Linux VDA – Post build tasks and Linux VDA 1912 preparation

Post install initial setup

Once the machine has finished installing and been rebooted it will load up the GNOME GUI and guide you through the initial setup where you have to accept the license agreement, select your language,

To perform this initial setup following installation perform the following steps:

  • In the INITIAL SETUP screen click on the LICENSE INFORMATION option
  • Click on the I accept the license agreement tickbox at the bottom of the screen
  • Click on Done to return to the INITIAL SETUP screen
  • Click on the FINISH CONFIGURATION button at the bottom right of the screen
  • GNOME will now load and present you with a Welcome screen where you can choose your language.  If not already selected, choose the language you require and then click on the blue Next button at the top right of the screen
  • Next if not already selected choose the keyboard layout you require and then click on the blue Next button at the top right of the screen
  • When prompted select the Time Zone you require and then click on the blue Next button at the top right of the screen
  • When prompted for Online Accounts click on Skip at the top right of the screen (For the purposes of this article, users will be from a company Active Directory)
  • At the About You screen configure a Full Name and a Username for a local account on the server  and then click on the blue Next button at the top right of the screen. (For the purposes of this article, this was set to localuser so that there is no confusion with Active Directory credentials later on)
  • When prompted set a password for the local account and then click on the blue Next button at the top right of the screen
  • Finally at the Ready to Go screen click on the blue Start using CentOS Linux button to complete the initial setup

Install Citrix XenTools

The next step in this set of instructions is to install the Citrix XenTools on to the machine as they are a prerequisite for deploying machines using Machine Creation Services (MCS) later on.

To install Citrix XenTools perform the following steps:

  • Attached the guest-tools.iso to the virtual machine
  • Mount the CD to the /mnt directory on the machine by executing the following:
mount /dev/cdrom /mnt
  • Change to the Linux tools directory by executing the following:
cd /mnt/Linux
  • Run the install.sh script by executing the following:
./install.sh
  • The script should detect that the machine is running CentOS as shown below and when prompted enter y to proceed:
Detected `CentOS Linux release 7.3.1611 (Core) ' (centos version 7).

The following changes will be made to this Virtual Machine:
 * update arp_notify sysctl.
 * packages to be installed/upgraded:
 - xe-guest-utilities-7.11.0-1.x86_64.rpm
 - xe-guest-utilities-xenstore-7.11.0-1.x86_64.rpm

Continue? [y/n]
  • The tools will now be installed and then return to the command prompt.
  • Unmount the CD by executing the following:
umount /mnt
  • Eject the CD from the virtual machine and then reboot the machine by executing reboot at the command prompt
  • Once the machine is rebooted confirm in XenCentre that the tools are installed by selecting the VM and clicking the General tab.  As can be seen in the screenshot below, the Virtualization state is shown as Optimized (version 8.0 installed) meaning that XenTools is installed correctly.

xentools-installed

You can also confirm that XenTools is installed correctly by going to the Performance tab of the VM.  If the Memory Performance graph is visible then the tools are installed correctly.

Update the installation

The next step is to update the machine using YUM (Yellowdog Updater, Modified) so that it is running the latest package versions.  For the purposes of this article the virtual machine has been granted access to the Internet to perform the updates but this may differ in your environment.  Configuring local repositories or setting proxy settings to allow updates is beyond the scope of this article.

To update the machine using YUM perform the following steps in a terminal session as the root account:

  • Initialize the update by executing the following:
yum update
  • When prompted enter to y to proceed with the download of the packages and their installation.

Note: This can take a long time to perform depending on the resources assigned to the virtual machine, network connectivity, as well as how far behind the ISO used to build the machine is

  • Once the process is completed you should see a list of installed, updated, and replaced packages followed by Complete!
  • Reboot the machine by executing reboot at the command prompt

Configure chrony

The next step is to ensure that the machine’s time is synchronised to avoid VDA registration errors later on.  For the purposes of this article the chrony will be configured to point at an Active Directory Domain Controller.

To configure chrony perform the following steps in a terminal session as the root account:

  • Edit the /etc/chrony.conf file and comment out the centos servers listed using a # (hash symbol) as shown below:
#server 0.centos.pool.ntp.org iburst
#server 1.centos.pool.ntp.org iburst
#server 2.centos.pool.ntp.org iburst
#server 3.centos.pool.ntp.org iburst
  • Add a line below these point to your Domain Controller in the format of server {your Domain Controller FQDN or IP} iburst
  • The example below is pointing chrony to the IP Address 10.100.100.100 for my Domain Controller
server 10.100.100.100 iburst
  • Save and exit the file
  • Restart the chronyd service by executing the following:
service chronyd restart

Disable libvirtd virtualization toolkit

During my initial testing I was unaware that the libvirtd toolkit is installed as default with CentOS 7 and only realised when my VDA registered in DNS with an IP Address of 192.168.122.1.

This caused the VDA to fail registration with the DDC so for this article I disabled the libvirtd toolkit completely on the VDA as well as because you would not want a VDA to be capable of hosting virtual machines. For a full explanation see the article from The Geek Diary CentOS / RHEL 6,7 : How to disable or delete virbr0 interface

To disable the libvirtd toolkit perform the following steps in a terminal session as the root account:

  • Disable and remove the libvirtd default network by executing the following commands:
# virsh net-destroy default
Network default destroyed

# virsh net-autostart default --disable
Network default unmarked as autostarted

# virsh net-undefine default
Network default has been undefined

chkconfig libvirtd off
Note: Forwarding request to 'systemctl disable libvirtd.service'.
Removed symlink /etc/systemd/system/multi-user.target.wants/libvirtd.service.
Removed symlink /etc/systemd/system/sockets.target.wants/virtlockd.socket.
Removed symlink /etc/systemd/system/sockets.target.wants/virtlogd.socket.

Disable graphical interface

The last step is to disable the graphical interface on the server so that when the server is booted it will come up to the normal non-gui logon page.

To disable the graphical interface perform the following steps in a terminal session as the root account:

  • Execute the following command to disable the graphical interface
systemctl set-default multi-user.target
  • Reboot the server

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