Black lives matter.

We stand in solidarity with the Black community.

Racism is unacceptable.

It conflicts with the core values of the Kubernetes project and our community does not tolerate it.

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 1.15

require (
	github.com/go-logr/logr v0.3.0
	github.com/onsi/ginkgo v1.14.1
	github.com/onsi/gomega v1.10.2
	github.com/robfig/cron v1.2.0
	k8s.io/api v0.19.2
	k8s.io/apimachinery v0.19.2
	k8s.io/client-go v0.19.2
	sigs.k8s.io/controller-runtime v0.7.0
)
`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,preserveUnknownFields=false"

# Get the currently used golang install path (in GOPATH/bin, unless GOBIN is set)
ifeq (,$(shell go env GOBIN))
GOBIN=$(shell go env GOPATH)/bin
else
GOBIN=$(shell go env GOBIN)
endif

all: manager

# Run tests
ENVTEST_ASSETS_DIR=$(shell pwd)/testbin
test: generate fmt vet manifests
	mkdir -p ${ENVTEST_ASSETS_DIR}
	test -f ${ENVTEST_ASSETS_DIR}/setup-envtest.sh || curl -sSLo ${ENVTEST_ASSETS_DIR}/setup-envtest.sh https://raw.githubusercontent.com/kubernetes-sigs/controller-runtime/v0.7.0/hack/setup-envtest.sh
	source ${ENVTEST_ASSETS_DIR}/setup-envtest.sh; fetch_envtest_tools $(ENVTEST_ASSETS_DIR); setup_envtest_env $(ENVTEST_ASSETS_DIR); go test ./... -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 manifests
	go run ./main.go

# Install CRDs into a cluster
install: manifests kustomize
	$(KUSTOMIZE) build config/crd | kubectl apply -f -

# Uninstall CRDs from a cluster
uninstall: manifests kustomize
	$(KUSTOMIZE) build config/crd | kubectl delete -f -

# Deploy controller in the configured Kubernetes cluster in ~/.kube/config
deploy: manifests kustomize
	cd config/manager && $(KUSTOMIZE) edit set image controller=${IMG}
	$(KUSTOMIZE) build config/default | kubectl apply -f -

# UnDeploy controller from the configured Kubernetes cluster in ~/.kube/config
undeploy:
	$(KUSTOMIZE) build config/default | kubectl delete -f -

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

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

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

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

# Build the docker image
docker-build: test
	docker build -t ${IMG} .

# Push the docker image
docker-push:
	docker push ${IMG}

# Download controller-gen locally if necessary
CONTROLLER_GEN = $(shell pwd)/bin/controller-gen
controller-gen:
	$(call go-get-tool,$(CONTROLLER_GEN),sigs.k8s.io/controller-tools/cmd/controller-gen@v0.4.1)

# Download kustomize locally if necessary
KUSTOMIZE = $(shell pwd)/bin/kustomize
kustomize:
	$(call go-get-tool,$(KUSTOMIZE),sigs.k8s.io/kustomize/kustomize/v3@v3.8.7)

# go-get-tool will 'go get' any package $2 and install it to $1.
PROJECT_DIR := $(shell dirname $(abspath $(lastword $(MAKEFILE_LIST))))
define go-get-tool
@[ -f $(1) ] || { \
set -e ;\
TMP_DIR=$$(mktemp -d) ;\
cd $$TMP_DIR ;\
go mod init tmp ;\
echo "Downloading $(2)" ;\
GOBIN=$(PROJECT_DIR)/bin go get $(2) ;\
rm -rf $$TMP_DIR ;\
}
endef
`PROJECT`: Kubebuilder metadata for scaffolding new components
domain: tutorial.kubebuilder.io
layout: go.kubebuilder.io/v3
projectName: project
repo: tutorial.kubebuilder.io/project
resources:
- api:
    crdVersion: v1
  group: batch
  kind: CronJob
  version: v1
  webhooks:
    webhookVersion: v1
version: 3-alpha

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...