kpack

What kpack is

kpack is a Kubernetes-native service for building OCI images with Cloud Native Buildpacks. Its declarative resources define build behavior: a builder sets the buildpack order and operating-system stack, while an image resource schedules builds and rebuilds after source code, buildpacks, or stacks change. A separate build resource runs a single build. Images are published to a configured tag, with additional tags limited to that same registry. Image resources support volume-based or registry-based caching, and Kubernetes secrets can provide credentials for publishing images and accessing private Git repositories. The build method is daemonless, with multiple cache backends. kpack is free and open source under the Apache-2.0 license, for API use in a self-hosted setup. Installation requires Kubernetes 1.22 or later, kubectl, cluster-admin permissions, and an accessible Docker V2 registry. SSH host key checking for Git credentials is disabled by default, though it can be enabled through a controller environment variable. Legacy Cloud Native Buildpacks service bindings are deprecated in kpack.io/v1alpha2 and are expected to be removed.

Who it suits

kpack suits teams building Cloud Native Buildpacks OCI images in a Kubernetes environment. It requires cluster-admin permissions and access to a Docker V2 registry, so it is for teams able to provide those prerequisites.

Limits

The free plan requires a Kubernetes cluster, kubectl, cluster-admin permissions, and an accessible Docker V2 registry. Additional image tags must use the same registry as the configured image tag.

Getting started

1. Prepare Kubernetes 1.22 or later and kubectl.
2. Obtain cluster-admin permissions and access to a Docker V2 registry.
3. Install kpack using the project's GitHub site.
4. Configure a builder resource with the buildpack order and operating system stack.
5. Set up an image resource for scheduled builds, or a build resource for a one-off build.
6. Provide registry or private Git credentials with Kubernetes secrets as needed.

Verdict

kpack provides declarative, daemonless image builds and automatic rebuilds within Kubernetes. Check the registry constraint and installation requirements before adopting it.