Inside Kube-OVN: How the Controller Manages VPCs, Workers, and IP Allocation

Controller Deployment

The kube-ovn-controller runs as a Deployment in a Kubernetes cluster. The install.sh script generates manifests based on configuration and applies them. The controller image is kubeovn/kube-ovn:v1.8.0; the entrypoint is the kube-ovn-controller binary.

Main Execution Flow

main Function

The main function creates informers, starts worker loops, and launches the controller.

Worker Model

For each CRD resource (VPC, subnet, pod, etc.) the controller creates a dedicated Go routine with its own work queue. Events are enqueued and processed asynchronously.

VPC Add Event Example

When a VPC add event arrives, it is placed in the VPC work queue. The VPC worker calls InitDefaultVpc() to ensure a default VPC named ovn-cluster exists, then creates an OVN logical router using ovn-nbctl lr-add.

InitDefaultVpc()

Default VPC Initialization

After installation Kube‑OVN automatically creates a default VPC ( ovn-cluster). All user‑created subnets and pods belong to this VPC unless a custom VPC is specified. The default VPC includes at least one OVN logical router, providing isolation between VPCs.

VPC Resource Handling

The VPC worker processes add, update, and delete events. For add, it creates the logical router and, for custom VPCs, configures static routes. Subnet and pod workers follow the same queue‑driven pattern.

Key Initialization Commands

# Ensure default VPC
InitDefaultVpc()

# Create logical router (example)
ovn-nbctl lr-add ovn-cluster

References

Project repository: https://github.com/kubeovn/kube-ovn

Official site: https://www.kube-ovn.io

Slack community: https://kube-ovn-slackin.herokuapp.com