Create a VM Template for Ubuntu 18.04 LTS

Script the Boring Stuff

Image credit: Unsplash

Why

Creating a template in vSphere allows for rapid deployment of VMs. You can add or update custom software and build the perfect server to be consistently deployed in your enviornment.

My goal is to create a VM, add VMware tools, and strip out any unique data.


Before We Start

  • Download the ISO of Ubuntu 18.04 LTS
  • Upload the Ubuntu 18.04 ISO to a vSphere datastore.
  • Create a VM using that ISO (including full post install / OS setup)
  • SSH into the newly created VM

Customize The Template

I’ve included the manual steps below that are needed to clean up your template. If you want to take the fast track you can just run this script and skip to the next section.

Update All Packages

# use caution when using -y (automatic "yes")
sudo apt -y update
sudo apt -y upgrade

Install VMware Tools

# most likely is already installed
sudo apt -y install open-vm-tools

Strip Out Unique Data

#Stop services for cleanup
sudo service rsyslog stop

#clear audit logs
if [ -f /var/log/wtmp ]; then
    truncate -s0 /var/log/wtmp
fi
if [ -f /var/log/lastlog ]; then
    truncate -s0 /var/log/lastlog
fi

#cleanup /tmp directories
rm -rf /tmp/*
rm -rf /var/tmp/*

#cleanup current ssh keys
rm -f /etc/ssh/ssh_host_*

#add check for ssh keys on reboot...regenerate if neccessary
cat << 'EOL' | sudo tee /etc/rc.local
#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.
# dynamically create hostname (optional)
#if hostname | grep localhost; then
#    hostnamectl set-hostname "$(head /dev/urandom | tr -dc A-Za-z0-9 | head -c 13 ; echo '')"
#fi
test -f /etc/ssh/ssh_host_dsa_key || dpkg-reconfigure openssh-server
exit 0
EOL

# make sure the script is executable
chmod +x /etc/rc.local

#reset hostname
# prevent cloudconfig from preserving the original hostname
sed -i 's/preserve_hostname: false/preserve_hostname: true/g' /etc/cloud/cloud.cfg
truncate -s0 /etc/hostname
hostnamectl set-hostname localhost

#cleanup apt
apt clean

# set dhcp to use mac - this is a little bit of a hack but I need this to be placed under the active nic settings
# also look in /etc/netplan for other config files
sed -i 's/optional: true/dhcp-identifier: mac/g' /etc/netplan/50-cloud-init.yaml

# cleans out all of the cloud-init cache / logs - this is mainly cleaning out networking info
sudo cloud-init clean --logs

#cleanup shell history
cat /dev/null > ~/.bash_history && history -c
history -w

#shutdown
shutdown -h now

Optional Configuration For kubeadm

# disable swap
sudo swapoff --all
sudo sed -ri '/\sswap\s/s/^#?/#/' /etc/fstab

# If you want to dynamically create a hostname, uncomment the below from /etc/rc.local:
# dynamically create hostname (optional)
# if hostname | grep localhost; then
#   hostnamectl set-hostname "$(head /dev/urandom | tr -dc A-Za-z0-9 | head -c 13 ; echo '')"
#fi

Add As A Template To vSphere

At this point, we’ve customized the VM and it should be shut off.

Make sure to disconnect the CDROM and the NIC before adding as template
Right Click VM > Edit Settings > deselect…
  • Right Click VM > convert to template

Conclusion

That’s it! I plan on using these VM templates for my Kubernetes clusters.

Jim Angel
Jim Angel
Everything Computers & Cloud

I’m an Infrastructure Cloud Consultant at Google. I love demystifying Kubernetes and related concepts. Part of my journey includes serving as a documentation co-chair for Kubernetes.

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