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 consistently deploy in your environment.

I aim 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 necessary
cat << 'EOL' | sudo tee /etc/rc.local
#!/bin/sh -e
#
# 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
#
# check for SSH keys and create if not present
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 cloud-init 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 - keying off of a default line is a little bit of a hack to insert the replacement text, but we need the replaced text inserted 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 create a hostname dynamically, 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 should shut it off.

Warning

Make sure to disconnect the CDROM and the NIC before adding as the image as a 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.