BuildKit CLI for kubectl is a tool for building OCI and Docker images with your kubernetes cluster. It replaces the docker build command to let you quickly and easily build your single and multi-architecture container images.

The BuildKit CLI for kubectl replaces the docker build command with kubectl build to build images in your kubernetes cluster, instead of on a single node. Your Dockerfile will be parsed the same way as with the existing docker build command, and build flags should feel almost the same.

Regardless of whether your Kubernetes cluster is using pure containerd or docker, the builder will be able to build OCI compatible images. These images can be used inside of your cluster, or pushed to an image registry for distribution.

The BuildKit builder should work in most Kubernetes environments. We tested it with:

• vSphere Tanzu
• Amazon EKS
• Minikube
• VMware Fusion
• Docker Desktop
• k0s
• k3d (limited support)

You should use Kubernetes version 1.14 or greater.

If you need to support building multi-architecture images, the builder can create those by cross-compiling your binaries. Multi-architecture images allow you to create images with the same tag so that when they are pulled, the correct image for the architecture will be used. This includes architectures such as:

• linux/amd64 (Intel based 64 bit images)
• linux/386 (Intel based 32 bit images)
• linux/arm/v7 (ARM based 32 bit images - Raspberry Pi)
• linux/arm64 (ARM based 64 bit images)
• windows/amd64 (Intel based 64 bit Windows images)

Future versions will include native builds in mixed clusters, as well as being able to emulate architectures when it's difficult to cross-compile. Check out the multi-architecture documentation for more information.

Head over to https://github.com/vmware-tanzu/buildkit-cli-for-kubectl/releases and download the tgz asset for your platform.

Once downloaded, extract it into your path. For example, on MacOS

cat darwin-*.tgz | tar -C /usr/local/bin -xvf -

Test your install with

kubectl build --help

Check out our contributing guide for instructions on setting up your environment and build instructions

If you're using more than one kubernetes environment, switch to the context you wish to use with the buildkit builder.

kubectl config get-contexts
kubectl config use-context <context name>

If you're going to push a newly created image to a container registry, you will need to store your container registry credentials. This can be done either by passing a secret through a multi-stage Dockerfile, or with a registry secret inside of Kubernetes. Although either method can store your plaintext password, you should consider creating an API key in your registry to be more secure.

To create a registry secret inside of Kubernetes, use the command:

read -s REG_SECRET
kubectl create secret docker-registry mysecret --docker-server='<registry hostname>' --docker-username=<user name> --docker-password=$REG_SECRET
kubectl build --push --registry-secret mysecret -t <registry hostname>/<namespace>/<repo>:<tag> -f Dockerfile ./

Check out our contributing for guidance on how to help contribute to the project.

This project wouldn't have been possble without the awesome upstream work from BuildKit which serves as the back-end builder, and buildx which this CLI was derived from.