k8s-image-controller

This repository implements a Kubernetes controller for watching and building Image resources defined with a CustomResourceDefinition (CRD).

Implementation

• For each Image
  • Create Job
  • Find existing Jobs owned by Image
  • If not found, apply Job and return
  • If found, compare to created Job
  • If same, return
  • If different, apply Job

Development

It makes use of the generators in k8s.io/code-generator to generate a typed client, informers, listers and deep-copy functions. You can do this yourself using the ./hack/update-codegen.sh script.

The update-codegen script will automatically generate the following files & directories:

• pkg/apis/imagecontroller/v1alpha1/zz_generated.deepcopy.go
• pkg/generated/

Changes should not be made to these files manually, and when creating your own controller based off of this implementation you should not copy these files and instead run the update-codegen script to generate your own.

Running

Prerequisite: Since the image-controller uses apps/v1 deployments, the Kubernetes cluster version should be greater than 1.9.

# assumes you have a working kubeconfig, not required if operating in-cluster
go build  .
./k8s-image-controller -kubeconfig=$HOME/.kube/config

# create the CustomResourceDefinition
kubectl create -f deploy/crd-status-subresource.yaml

# create a custom resource of type Image
kubectl create -f examples/example-image.yaml

# check images created
kubectl get images

TODO

• Updating image should create new job
• Support build args
• Add Builder CRD
• Add telemetry
• Support build context
• Add ready status