Kubebuilder Demo

This repo is a demo project, which is scaffoled by kubebuilder for showing how Bounded Deployment works. CRD will be created and installed to cluster as a Kubernetes resource. Requests of creating a CR object from kubectl is received by Kubernetes API server, which will invoke Webhook for handling. API server patches the response from Webhook for creating this object eventually. Controller is consistently watching and reconciling this object.

Prerequisites

• go 1.10 or newer
• dep v0.5.0 or newer
• kubebuilder v1.0.5 or newer
• a minikube cluster with version v0.30.0 or newer
  • Install minikube
  • Reusing the Docker daemon

How to Start

git clone the repo under your GOPATH.

Run eval $(minikube docker-env) after minikube starts. We will reuse the docker daemon in minikube.

Run ./start_demo.sh.

Under the hood of demo

Build and Deploy

1. Scaffold a project
2. Scaffold a CRD API
3. Scaffold a controller
4. Scaffold a mutating webhook
5. Fill the business logic by applying a patch
6. Run make
7. Modify instances of CR by applying a patch.
8. Build image by make docker-build
9. (Skipped) Push image by make docker-push
10. Deploy by make deploy

Note: make docker-push pushes images to your registry. This step is skipped in the demo because we reuse the docker daemon in minikube.

Controller

Controller creates deployment with the same replicas specified in the CR.

Webhook

The mutating webhook modifies the CR. If the replicas field is not set, default it to 2. If the replicas > 2, it change it to 2.

Verify Controller and Webhook Work

1. Create a instance of CR with replicas=10
2. Verify a deployment with replicas=2 has been created.