What’s in a basic project?

When scaffolding out a new project, Kubebuilder provides us with a few basic pieces of boilerplate.

Build Infrastructure

First up, basic infrastructure for building your project:

go.mod: A new Go module matching our project, with basic dependencies

module tutorial.kubebuilder.io/project

go 1.12

require (
    github.com/go-logr/logr v0.1.0
    github.com/robfig/cron v1.1.0
    k8s.io/api v0.0.0-20190222213804-5cb15d344471
    k8s.io/apimachinery v0.0.0-20190221213512-86fb29eff628
    k8s.io/client-go v0.0.0-20190228174230-b40b2a5939e4
    sigs.k8s.io/controller-runtime v0.2.0-alpha.0.0.20190503051552-b666157c41da
    sigs.k8s.io/controller-tools v0.2.0-alpha.1 // indirect

Makefile: Make targets for building and deploying your controller

# Image URL to use all building/pushing image targets
IMG ?= controller:latest
# Produce CRDs that work back to Kubernetes 1.11 (no version conversion)
CRD_OPTIONS ?= "crd:trivialVersions=true"

all: manager

# Run tests
test: generate fmt vet manifests
    go test ./api/... ./controllers/... -coverprofile cover.out

# Build manager binary
manager: generate fmt vet
    go build -o bin/manager main.go

# Run against the configured Kubernetes cluster in ~/.kube/config
run: generate fmt vet
    go run ./main.go

# Install CRDs into a cluster
install: manifests
    kubectl apply -f config/crd/bases

# Deploy controller in the configured Kubernetes cluster in ~/.kube/config
deploy: manifests
    kubectl apply -f config/crd/bases
    kustomize build config/default | kubectl apply -f -

# Generate manifests e.g. CRD, RBAC etc.
manifests: controller-gen
    $(CONTROLLER_GEN) $(CRD_OPTIONS) rbac:roleName=manager-role webhook paths="./api/...;./controllers/..." output:crd:artifacts:config=config/crd/bases

# Run go fmt against code
    go fmt ./...

# Run go vet against code
    go vet ./...

# Generate code
generate: controller-gen
    $(CONTROLLER_GEN) object:headerFile=./hack/boilerplate.go.txt paths=./api/...

# Build the docker image
docker-build: test
    docker build . -t ${IMG}
    @echo "updating kustomize image patch file for manager resource"
    sed -i'' -e 's@image: .*@image: '"${IMG}"'@' ./config/default/manager_image_patch.yaml

# Push the docker image
    docker push ${IMG}

# find or download controller-gen
# download controller-gen if necessary
ifeq (, $(shell which controller-gen))
    go get sigs.k8s.io/controller-tools/cmd/controller-gen@v0.2.0-alpha.1
CONTROLLER_GEN=$(shell go env GOPATH)/bin/controller-gen
CONTROLLER_GEN=$(shell which controller-gen)

PROJECT: Kubebuilder metadata for scaffolding new components

version: "2"
domain: tutorial.kubebuilder.io
repo: tutorial.kubebuilder.io/project

Launch Configuration

We also get launch configurations under the config/ directory. Right now, it just contains Kustomize YAML definitions required to launch our controller on a cluster, but once we get started writing our controller, it’ll also hold our CustomResourceDefinitions, RBAC configuration, and WebhookConfigurations.

config/default contains a Kustomize base for launching the controller in a standard configuration.

Each other directory contains a different piece of configuration, refactored out into its own base:

  • config/manager: launch your controllers as pods in the cluster

  • config/rbac: permissions required to run your controllers under their own service account

The Entrypoint

Last, but certainly not least, Kubebuilder scaffolds out the basic entrypoint of our project: main.go. Let’s take a look at that next...