Create a VM template for Ubuntu 18.04 LTS

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 consitently 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
# -s0 sets the bites to 0 erasing the file
sudo truncate -s0 /var/log/wtmp
sudo truncate -s0 /var/log/lastlog

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

#cleanup current ssh keys
sudo 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.
#

# dynamically create hostname
if hostname | grep localhost; then
    hostnamectl set-hostname $(head /dev/urandom | tr -dc A-Za-z0-9 | head -c 13 ; echo '')
fi

# By default this script does nothing.
test -f /etc/ssh/ssh_host_dsa_key || dpkg-reconfigure openssh-server
exit 0
EOL

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

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

#cleanup apt
sudo apt clean

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

#cleanup shell history
history -c
history -w

Optional configuration for kubeadm

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

# TO DO: bring the hostname junk down here

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…

  1. Right Click VM > convert to template

Conclusion

That’s it! I plan on using these VMs for my needs

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