Kubernetes allows for extensions to its architecture in the form of custom resources: https://kubernetes.io/docs/concepts/extend-kubernetes/api-extension/custom-resources/. KubeVirt represents virtual machines as custom resources and manages changes to libvirt domains based on the state of those resources.
- virt-api: This component provides a HTTP RESTful entrypoint to manage the virtual machines within the cluster.
- virt-controller: This component manages the state of each VMI within the Kubernetes cluster.
- virt-handler: This is a daemon that runs on each Kubernetes node. It is responsible for monitoring the state of VMIs according to Kubernetes and ensuring the corresponding libvirt domain is booted or halted accordingly.
- virt-launcher: This component is a place-holder, one per running VMI. It contains the running VMI and remains running as long as the VMI is defined.
cluster/kubectl.sh: This is a wrapper around Kubernetes' kubectl command so that it can be run directly from this checkout without logging into a node.cluster/virtctl.shis a wrapper aroundvirtctl.virtctlbrings all virtual machine specific commands with it. It is supplement tokubectl. e.g.cluster/virtctl.sh console testvm.cluster/cli.shhelps you creating ephemeral kubernetes and openshift clusters for testing. This is helpful when direct management or access to cluster nodes is necessary. e.g.cluster/cli.sh ssh node01.
make cluster-up: This will deploy a fresh environment, the contents ofKUBE_PROVIDERwill be used to determine which provider from theclusterdirectory will be deployed.make cluster-sync: After deploying a fresh environment, or after making changes to code in this tree, this command will sync the Pods and DaemonSets in the running KubeVirt environment with the state of this tree.make cluster-down: This will tear down a running KubeVirt enviornment.