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Kubebuilder v2 vs v3 (Legacy Kubebuilder v2.0.0+ layout to 3.0.0+)

This document covers all breaking changes when migrating from v2 to v3.

The details of all changes (breaking or otherwise) can be found in controller-runtime, controller-tools and kb-releases release notes.

Common changes

v3 projects use Go modules and request Go 1.18+. Dep is no longer supported for dependency management.


  • Preliminary support for plugins was added. For more info see the Extensible CLI and Scaffolding Plugins: phase 1, the Extensible CLI and Scaffolding Plugins: phase 1.5 and the Extensible CLI and Scaffolding Plugins - Phase 2 design docs. Also, you can check the Plugins section.

  • The PROJECT file now has a new layout. It stores more information about what resources are in use, to better enable plugins to make useful decisions when scaffolding.

    Furthermore, the PROJECT file itself is now versioned: the version field corresponds to the version of the PROJECT file itself, while the layout field indicates the scaffolding & primary plugin version in use.

  • The version of the image, which is an optional component enabled by default to secure the request made against the manager, was updated from 0.5.0 to 0.11.0 to address security concerns. The details of all changes can be found in kube-rbac-proxy.

TL;DR of the New go/v3 Plugin

More details on this can be found at here, but for the highlights, check below

  • Scaffolded/Generated API version changes:

    • Use apiextensions/v1 for generated CRDs (apiextensions/v1beta1 was deprecated in Kubernetes 1.16)
    • Use for generated webhooks ( was deprecated in Kubernetes 1.16)
    • Use for the certificate manager when webhooks are used ( was deprecated in Cert-Manager 0.14. More info: CertManager v1.0 docs)
  • Code changes:

    • The manager flags --metrics-addr and enable-leader-election now are named --metrics-bind-address and --leader-elect to be more aligned with core Kubernetes Components. More info: #1839
    • Liveness and Readiness probes are now added by default using healthz.Ping.
    • A new option to create the projects using ComponentConfig is introduced. For more info see its enhancement proposal and the Component config tutorial
    • Manager manifests now use SecurityContext to address security concerns. More info: #1637
  • Misc:

    • Support for controller-tools v0.9.0 (for go/v2 it is v0.3.0 and previously it was v0.2.5)
    • Support for controller-runtime v0.12.1 (for go/v2 it is v0.6.4 and previously it was v0.5.0)
    • Support for kustomize v3.8.7 (for go/v2 it is v3.5.4 and previously it was v3.1.0)
    • Required Envtest binaries are automatically downloaded
    • The minimum Go version is now 1.18 (previously it was 1.13).

Migrating to Kubebuilder v3

So you want to upgrade your scaffolding to use the latest and greatest features then, follow up the following guide which will cover the steps in the most straightforward way to allow you to upgrade your project to get all latest changes and improvements.

By updating the files manually

So you want to use the latest version of Kubebuilder CLI without changing your scaffolding then, check the following guide which will describe the manually steps required for you to upgrade only your PROJECT version and starts to use the plugins versions.

This way is more complex, susceptible to errors, and success cannot be assured. Also, by following these steps you will not get the improvements and bug fixes in the default generated project files.

You will check that you can still using the previous layout by using the go/v2 plugin which will not upgrade the controller-runtime and controller-tools to the latest version used with go/v3 becuase of its breaking changes. By checking this guide you know also how to manually change the files to use the go/v3 plugin and its dependencies versions.