It’s just broken up like this to make it easier to read. Note that even though each of these entries is a new item in the array in our config file, they all get entered as a single line. Then, the large number of are shortcode for backspace – we’re deleting all the prefilled boot commands so we can type our own. The first two lines get us from the splash screen to the custom boot command entry on the installer. There are a few interesting points to notice here. This is a command that is typed at the install prompt when the ISO boots. The most interesting part of this step is configuring the boot_command. You can see a full example of the Packer file we use here.

While it is possible to start from another image, we prefer this method because it gives us total control over what goes in the image.

To build our Ubuntu 20.04 image, we start from scratch using the ISO. I’m going to talk about a few of the things we do to provision our images, but it’s worth noting that there are the chef-maintaned bento boxes you can look at for full examples. You can have multiple builders in a single Packer configuration, which means you can effectively build an identical image for multiple platforms very easily. For example, that may be an AMI for EC2 or a file such as a vmdk for VMWare images. Once those scripts have been run, Packer will shut down the VM and export it in some way depending on the builder. Builders define how to launch a VM on a particular platform, while the provisioners define what scripts to run on that image to prepare it in the way you want. In a nutshell, a Packer configuration consists of an array of builders and, optionally, an array of provisioners. The Packer Getting Started guide gives a good overview of how to use it. Our Virtualbox images are used by developers using Vagrant on their local systems, and our VMWare images are used for both Vagrant and our internal Openstack platform (which we use VMWare vCenter / ESXi for the compute resources). Natively it supports a huge range of virtualisation options, but for our purpose, we use Virtualbox and VMWare Workstation. Packer is a tool from Hashicorp that automates the building of machine images. This post is about how we use Packer to automate the creation of images and what we had to do to get it to build Ubuntu 20.04. Ubuntu 20.04 was released last week, so I set about creating a new image for our internal virtualisation platform.

Ubuntu virtualbox images