Imagine is a small tool that creates a Vagrant base image. I maintain for my personal use and learning. Other tools like VeeWee or BoxGrinder would do the job very well but I wanted to get my hands dirty and solve the same problem using good old Bash.

To achieve our goal, we need the official Centos 6 ISO image, a Bash script and a kickstart script.

This is a work in progress:

• the script is geared toward OSX and you will need to adapt it for other operating systems,
• some of the hardcoded code would need to adapted to your requirement.

Please find the code on github and read the README file.

1. Command Line

If you look under imagine/virtualbox, you will find the create-base-image command which is used like this:

create-base-image vmname iso_file kickstart_file

where

• vmname is the name of the base image,
• iso_file is the path to the download Centos 6 ISO on your file system,
• kickstart_file is the kickstart file that will be used to customize your base image.

You will need to download Centos 6 base image from a mirror near you.

If you have download the CentOS-6.3-x86_64-bin-DVD1.iso base image in the /tmp directory, the following command will automatically create a new base image with the vagrant user in the ~/stores/ovf/test directory.

./create-base-image test /tmp/CentOS-6.3-x86_64-bin-DVD1.iso centos6-ks.cfg

You can change the target directory either by modifying the Bash script or by setting the OVF_STORE to the root your ovf store.

2. The Code

The code is separated in two parts:

1. the Bash script that interacts with VirtualBox using the VBoxManage command line,
2. the kickstart script that provides the initial configuration and the post install scripts.

2.1 Bash script

The role of the Bash script is to

• create a new virtual machine,
• create an empty hard drive image and mount it,
• create a floppy image countaining the kickstart script and mount it using code from here,
• mount the OS iso image,
• boot the VM,
• select the kickstart boot script from the floppy using the BoxManage controlvm keyboardputscancode command,
• reboot several times to allow the post installation script to run and clean itself.

The main trick is to use a mounted floppy to allow kickstart installation without having to rely on any network kickstart server and the related DHCP configuration. Thanks to VirtualBox ability to send keystrokes to a VM, as described here, we can automatically select the kickstart file on the floppy disk on boot.

2.2 Kickstart script

The kickstart script is a template. Any ${variable name} place holder will be replaced by the corresponding exported variable from the bash script using a simple Perl command.

In addition to the standard kickstart commands, the script will:

• create a local user with name ${USERNAME},
• copy your public ssh key in this user authorized_keys file,
• create a post installation script under /etc/rc3.d.

The post installation script will be run during the next reboot and, in this case, will install VirtualBox Guest Additions. It will then clean itself.

Conclusion

This little tool shows how simple it is to create and customize a base image using simple tools like Bash and kickstart. Hopefully, you will find it usefull.

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