Part 3: Automated Boot Sources & Custom Golden Images with CDI

In the third part of this series, the focus is on building custom golden OS images and automating their import using CDI in OpenShift Virtualization. Traditional virtualization provisioning often involved downloading large ISO files and manually installing an OS, but OpenShift Virtualization offers an automated approach that enables virtual machines to spin up in seconds, similar to containers.

The automated pipeline consists of three core stages: packaging the raw disk into a lightweight containerDisk, storing the image in the OpenShift Internal Registry, and configuring CDI to continuously pull updates and make them available for instant VM cloning. To build the containerDisk, ensure the raw qcow2 file has read-only permissions and correct ownership, then create a Containerfile specifying the image source and permissions.

Push the image to the OpenShift Internal Registry using the internal registry route and authenticate using a pull secret created with the cluster CA. Configure authentication and TLS certificates for CDI, create a pull secret for the importer pod, extract the cluster CA for TLS verification, and bind it to a configmap. Finally, deploy the DataImportCron to automate updates, specifying annotations for immediate storage allocation and storage requirements.

Developers can then spin up a VM in seconds using the managed DataSource, avoiding lengthy provisioning times. The guide also addresses common errors engineers may encounter, such as token availability, file permissions, certificate issues, secret reference handling, and storage provisioning delays. By following these steps and avoiding pitfalls, organizations can efficiently manage custom golden images and maintain up-to-date VM environments with minimal manual intervention.