An Implementation of DNS Operator and Network Guideline for Migrating Virtual Machine to KubeVirt

Abstract

We created a customize DNS operator to address the shortcoming of CoreDNS in Kubernetes. While Kubernetes is gaining popularity in orchestrating containers, many organizations with Virtual Machine (VM) based legacy applications still struggle to containerize. Rehost strategy seems to be a faster method. On Kubernetes, KubeVirt can be used to manage rehosted VM. However, there is a huge difference between the long-term use of the VMs and containers. For example, container IP addresses change over time is problematic for VMs that need a static IP. In addition, some VM-based applications may require multiple network interfaces or a specific domain name for service discovery. These issues prevent some VMs from functioning properly after the migration to KubeVirt. We developed an operator framework to solve network problems that arise in the application layer such as DNS queries. In addition, we provide a guideline on how to use open-source projects like the Multus Container Network Interface, NMState to enable the migration of VMs with applications related to network function properly. Our operator and guideline allow most VMs to function properly with few modifications (to none) after migrating to KubeVirt. This facilitated the adoption of Kubernetes in more organizations.