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 1.20

require (
	github.com/onsi/ginkgo/v2 v2.11.0
	github.com/onsi/gomega v1.27.10
	github.com/robfig/cron v1.2.0
	k8s.io/api v0.28.3
	k8s.io/apimachinery v0.28.3
	k8s.io/client-go v0.28.3
	sigs.k8s.io/controller-runtime v0.16.3

require (
	github.com/beorn7/perks v1.0.1 // indirect
	github.com/cespare/xxhash/v2 v2.2.0 // indirect
	github.com/davecgh/go-spew v1.1.1 // indirect
	github.com/emicklei/go-restful/v3 v3.11.0 // indirect
	github.com/evanphx/json-patch/v5 v5.6.0 // indirect
	github.com/fsnotify/fsnotify v1.6.0 // indirect
	github.com/go-logr/logr v1.2.4 // indirect
	github.com/go-logr/zapr v1.2.4 // indirect
	github.com/go-openapi/jsonpointer v0.19.6 // indirect
	github.com/go-openapi/jsonreference v0.20.2 // indirect
	github.com/go-openapi/swag v0.22.3 // indirect
	github.com/go-task/slim-sprig v0.0.0-20230315185526-52ccab3ef572 // indirect
	github.com/gogo/protobuf v1.3.2 // indirect
	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
	github.com/golang/protobuf v1.5.3 // indirect
	github.com/google/gnostic-models v0.6.8 // indirect
	github.com/google/go-cmp v0.5.9 // indirect
	github.com/google/gofuzz v1.2.0 // indirect
	github.com/google/pprof v0.0.0-20210720184732-4bb14d4b1be1 // indirect
	github.com/google/uuid v1.3.0 // indirect
	github.com/imdario/mergo v0.3.6 // indirect
	github.com/josharian/intern v1.0.0 // indirect
	github.com/json-iterator/go v1.1.12 // indirect
	github.com/mailru/easyjson v0.7.7 // indirect
	github.com/matttproud/golang_protobuf_extensions v1.0.4 // indirect
	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
	github.com/modern-go/reflect2 v1.0.2 // indirect
	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
	github.com/pkg/errors v0.9.1 // indirect
	github.com/prometheus/client_golang v1.16.0 // indirect
	github.com/prometheus/client_model v0.4.0 // indirect
	github.com/prometheus/common v0.44.0 // indirect
	github.com/prometheus/procfs v0.10.1 // indirect
	github.com/spf13/pflag v1.0.5 // indirect
	go.uber.org/multierr v1.11.0 // indirect
	go.uber.org/zap v1.25.0 // indirect
	golang.org/x/exp v0.0.0-20220722155223-a9213eeb770e // indirect
	golang.org/x/net v0.17.0 // indirect
	golang.org/x/oauth2 v0.8.0 // indirect
	golang.org/x/sys v0.13.0 // indirect
	golang.org/x/term v0.13.0 // indirect
	golang.org/x/text v0.13.0 // indirect
	golang.org/x/time v0.3.0 // indirect
	golang.org/x/tools v0.9.3 // indirect
	gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect
	google.golang.org/appengine v1.6.7 // indirect
	google.golang.org/protobuf v1.30.0 // indirect
	gopkg.in/inf.v0 v0.9.1 // indirect
	gopkg.in/yaml.v2 v2.4.0 // indirect
	gopkg.in/yaml.v3 v3.0.1 // indirect
	k8s.io/apiextensions-apiserver v0.28.3 // indirect
	k8s.io/component-base v0.28.3 // indirect
	k8s.io/klog/v2 v2.100.1 // indirect
	k8s.io/kube-openapi v0.0.0-20230717233707-2695361300d9 // indirect
	k8s.io/utils v0.0.0-20230406110748-d93618cff8a2 // indirect
	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
	sigs.k8s.io/structured-merge-diff/v4 v4.2.3 // indirect
	sigs.k8s.io/yaml v1.3.0 // indirect
Makefile: Make targets for building and deploying your controller

# Image URL to use all building/pushing image targets
IMG ?= controller:latest
# ENVTEST_K8S_VERSION refers to the version of kubebuilder assets to be downloaded by envtest binary.

# 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
GOBIN=$(shell go env GOBIN)

# CONTAINER_TOOL defines the container tool to be used for building images.
# Be aware that the target commands are only tested with Docker which is
# scaffolded by default. However, you might want to replace it to use other
# tools. (i.e. podman)

# Setting SHELL to bash allows bash commands to be executed by recipes.
# Options are set to exit when a recipe line exits non-zero or a piped command fails.
SHELL = /usr/bin/env bash -o pipefail

.PHONY: all
all: build

##@ General

# The help target prints out all targets with their descriptions organized
# beneath their categories. The categories are represented by '##@' and the
# target descriptions by '##'. The awk command is responsible for reading the
# entire set of makefiles included in this invocation, looking for lines of the
# file as xyz: ## something, and then pretty-format the target and help. Then,
# if there's a line with ##@ something, that gets pretty-printed as a category.
# More info on the usage of ANSI control characters for terminal formatting:
# https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_parameters
# More info on the awk command:
# http://linuxcommand.org/lc3_adv_awk.php

.PHONY: help
help: ## Display this help.
	@awk 'BEGIN {FS = ":.*##"; printf "\nUsage:\n  make \033[36m<target>\033[0m\n"} /^[a-zA-Z_0-9-]+:.*?##/ { printf "  \033[36m%-15s\033[0m %s\n", $$1, $$2 } /^##@/ { printf "\n\033[1m%s\033[0m\n", substr($$0, 5) } ' $(MAKEFILE_LIST)

##@ Development

.PHONY: manifests
manifests: controller-gen ## Generate WebhookConfiguration, ClusterRole and CustomResourceDefinition objects.
	$(CONTROLLER_GEN) rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases

.PHONY: generate
generate: controller-gen ## Generate code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations.
	$(CONTROLLER_GEN) object:headerFile="hack/boilerplate.go.txt" paths="./..."

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

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

.PHONY: test
test: manifests generate fmt vet envtest ## Run tests.
	KUBEBUILDER_ASSETS="$(shell $(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path)" go test $$(go list ./... | grep -v /e2e) -coverprofile cover.out

# Utilize Kind or modify the e2e tests to load the image locally, enabling compatibility with other vendors.
.PHONY: test-e2e  # Run the e2e tests against a Kind k8s instance that is spun up.
	go test ./test/e2e/ -v -ginkgo.v
GOLANGCI_LINT = $(shell pwd)/bin/golangci-lint
	@[ -f $(GOLANGCI_LINT) ] || { \
	set -e ;\
	curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(shell dirname $(GOLANGCI_LINT)) $(GOLANGCI_LINT_VERSION) ;\

.PHONY: lint
lint: golangci-lint ## Run golangci-lint linter & yamllint

.PHONY: lint-fix
lint-fix: golangci-lint ## Run golangci-lint linter and perform fixes
	$(GOLANGCI_LINT) run --fix

##@ Build

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

.PHONY: run
run: manifests generate fmt vet ## Run a controller from your host.
	go run ./cmd/main.go

# If you wish to build the manager image targeting other platforms you can use the --platform flag.
# (i.e. docker build --platform linux/arm64). However, you must enable docker buildKit for it.
# More info: https://docs.docker.com/develop/develop-images/build_enhancements/
.PHONY: docker-build
docker-build: ## Build docker image with the manager.
	$(CONTAINER_TOOL) build -t ${IMG} .

.PHONY: docker-push
docker-push: ## Push docker image with the manager.

# PLATFORMS defines the target platforms for the manager image be built to provide support to multiple
# architectures. (i.e. make docker-buildx IMG=myregistry/mypoperator:0.0.1). To use this option you need to:
# - be able to use docker buildx. More info: https://docs.docker.com/build/buildx/
# - have enabled BuildKit. More info: https://docs.docker.com/develop/develop-images/build_enhancements/
# - be able to push the image to your registry (i.e. if you do not set a valid value via IMG=<myregistry/image:<tag>> then the export will fail)
# To adequately provide solutions that are compatible with multiple platforms, you should consider using this option.
PLATFORMS ?= linux/arm64,linux/amd64,linux/s390x,linux/ppc64le
.PHONY: docker-buildx
docker-buildx: ## Build and push docker image for the manager for cross-platform support
	# copy existing Dockerfile and insert --platform=${BUILDPLATFORM} into Dockerfile.cross, and preserve the original Dockerfile
	sed -e '1 s/\(^FROM\)/FROM --platform=\$$\{BUILDPLATFORM\}/; t' -e ' 1,// s//FROM --platform=\$$\{BUILDPLATFORM\}/' Dockerfile > Dockerfile.cross
	- $(CONTAINER_TOOL) buildx create --name project-v3-builder
	$(CONTAINER_TOOL) buildx use project-v3-builder
	- $(CONTAINER_TOOL) buildx build --push --platform=$(PLATFORMS) --tag ${IMG} -f Dockerfile.cross .
	- $(CONTAINER_TOOL) buildx rm project-v3-builder
	rm Dockerfile.cross

##@ Deployment

ifndef ignore-not-found
  ignore-not-found = false

.PHONY: install
install: manifests kustomize ## Install CRDs into the K8s cluster specified in ~/.kube/config.
	$(KUSTOMIZE) build config/crd | $(KUBECTL) apply -f -

.PHONY: uninstall
uninstall: manifests kustomize ## Uninstall CRDs from the K8s cluster specified in ~/.kube/config. Call with ignore-not-found=true to ignore resource not found errors during deletion.
	$(KUSTOMIZE) build config/crd | $(KUBECTL) delete --ignore-not-found=$(ignore-not-found) -f -

.PHONY: deploy
deploy: manifests kustomize ## Deploy controller to the K8s cluster specified in ~/.kube/config.
	cd config/manager && $(KUSTOMIZE) edit set image controller=${IMG}
	$(KUSTOMIZE) build config/default | $(KUBECTL) apply -f -

.PHONY: undeploy
undeploy: ## Undeploy controller from the K8s cluster specified in ~/.kube/config. Call with ignore-not-found=true to ignore resource not found errors during deletion.
	$(KUSTOMIZE) build config/default | $(KUBECTL) delete --ignore-not-found=$(ignore-not-found) -f -

##@ Build Dependencies

## Location to install dependencies to
LOCALBIN ?= $(shell pwd)/bin
	mkdir -p $(LOCALBIN)

## Tool Binaries
KUBECTL ?= kubectl
KUSTOMIZE ?= $(LOCALBIN)/kustomize
CONTROLLER_GEN ?= $(LOCALBIN)/controller-gen
ENVTEST ?= $(LOCALBIN)/setup-envtest

## Tool Versions

.PHONY: kustomize
kustomize: $(KUSTOMIZE) ## Download kustomize locally if necessary. If wrong version is installed, it will be removed before downloading.
	@if test -x $(LOCALBIN)/kustomize && ! $(LOCALBIN)/kustomize version | grep -q $(KUSTOMIZE_VERSION); then \
		echo "$(LOCALBIN)/kustomize version is not expected $(KUSTOMIZE_VERSION). Removing it before installing."; \
		rm -rf $(LOCALBIN)/kustomize; \
	test -s $(LOCALBIN)/kustomize || GOBIN=$(LOCALBIN) GO111MODULE=on go install sigs.k8s.io/kustomize/kustomize/v5@$(KUSTOMIZE_VERSION)

.PHONY: controller-gen
controller-gen: $(CONTROLLER_GEN) ## Download controller-gen locally if necessary. If wrong version is installed, it will be overwritten.
	test -s $(LOCALBIN)/controller-gen && $(LOCALBIN)/controller-gen --version | grep -q $(CONTROLLER_TOOLS_VERSION) || \
	GOBIN=$(LOCALBIN) go install sigs.k8s.io/controller-tools/cmd/controller-gen@$(CONTROLLER_TOOLS_VERSION)

.PHONY: envtest
envtest: $(ENVTEST) ## Download envtest-setup locally if necessary.
	test -s $(LOCALBIN)/setup-envtest || GOBIN=$(LOCALBIN) go install sigs.k8s.io/controller-runtime/tools/setup-envtest@latest
PROJECT: Kubebuilder metadata for scaffolding new components
# Code generated by tool. DO NOT EDIT.
# This file is used to track the info used to scaffold your project
# and allow the plugins properly work.
# More info: https://book.kubebuilder.io/reference/project-config.html
domain: tutorial.kubebuilder.io
- go.kubebuilder.io/v4
projectName: project
repo: tutorial.kubebuilder.io/project
- api:
    crdVersion: v1
    namespaced: true
  controller: true
  domain: tutorial.kubebuilder.io
  group: batch
  kind: CronJob
  path: tutorial.kubebuilder.io/project/api/v1
  version: v1
    defaulting: true
    validation: true
    webhookVersion: v1
version: "3"

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…