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 1.24.0 require ( github.com/onsi/ginkgo/v2 v2.22.0 github.com/onsi/gomega v1.36.1 github.com/robfig/cron v1.2.0 k8s.io/api v0.32.1 k8s.io/apimachinery v0.32.1 k8s.io/client-go v0.32.1 sigs.k8s.io/controller-runtime v0.20.4 ) require ( cel.dev/expr v0.18.0 // indirect github.com/antlr4-go/antlr/v4 v4.13.0 // indirect github.com/asaskevich/govalidator v0.0.0-20190424111038-f61b66f89f4a // indirect github.com/beorn7/perks v1.0.1 // indirect github.com/blang/semver/v4 v4.0.0 // indirect github.com/cenkalti/backoff/v4 v4.3.0 // indirect github.com/cespare/xxhash/v2 v2.3.0 // indirect github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect github.com/emicklei/go-restful/v3 v3.11.0 // indirect github.com/evanphx/json-patch/v5 v5.9.11 // indirect github.com/felixge/httpsnoop v1.0.4 // indirect github.com/fsnotify/fsnotify v1.7.0 // indirect github.com/fxamacker/cbor/v2 v2.7.0 // indirect github.com/go-logr/logr v1.4.2 // indirect github.com/go-logr/stdr v1.2.2 // indirect github.com/go-logr/zapr v1.3.0 // indirect github.com/go-openapi/jsonpointer v0.21.0 // indirect github.com/go-openapi/jsonreference v0.20.2 // indirect github.com/go-openapi/swag v0.23.0 // indirect github.com/go-task/slim-sprig/v3 v3.0.0 // indirect github.com/gogo/protobuf v1.3.2 // indirect github.com/golang/protobuf v1.5.4 // indirect github.com/google/btree v1.1.3 // indirect github.com/google/cel-go v0.22.0 // indirect github.com/google/gnostic-models v0.6.8 // indirect github.com/google/go-cmp v0.6.0 // indirect github.com/google/gofuzz v1.2.0 // indirect github.com/google/pprof v0.0.0-20241029153458-d1b30febd7db // indirect github.com/google/uuid v1.6.0 // indirect github.com/grpc-ecosystem/grpc-gateway/v2 v2.20.0 // indirect github.com/inconshreveable/mousetrap v1.1.0 // 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/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 v1.19.1 // indirect github.com/prometheus/client_model v0.6.1 // indirect github.com/prometheus/common v0.55.0 // indirect github.com/prometheus/procfs v0.15.1 // indirect github.com/spf13/cobra v1.8.1 // indirect github.com/spf13/pflag v1.0.5 // indirect github.com/stoewer/go-strcase v1.3.0 // indirect github.com/x448/float16 v0.8.4 // indirect go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.53.0 // indirect go.opentelemetry.io/otel v1.28.0 // indirect go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.28.0 // indirect go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc v1.27.0 // indirect go.opentelemetry.io/otel/metric v1.28.0 // indirect go.opentelemetry.io/otel/sdk v1.28.0 // indirect go.opentelemetry.io/otel/trace v1.28.0 // indirect go.opentelemetry.io/proto/otlp v1.3.1 // indirect go.uber.org/multierr v1.11.0 // indirect go.uber.org/zap v1.27.0 // indirect golang.org/x/exp v0.0.0-20240719175910-8a7402abbf56 // indirect golang.org/x/net v0.30.0 // indirect golang.org/x/oauth2 v0.23.0 // indirect golang.org/x/sync v0.8.0 // indirect golang.org/x/sys v0.26.0 // indirect golang.org/x/term v0.25.0 // indirect golang.org/x/text v0.19.0 // indirect golang.org/x/time v0.7.0 // indirect golang.org/x/tools v0.26.0 // indirect gomodules.xyz/jsonpatch/v2 v2.4.0 // indirect google.golang.org/genproto/googleapis/api v0.0.0-20240826202546-f6391c0de4c7 // indirect google.golang.org/genproto/googleapis/rpc v0.0.0-20240826202546-f6391c0de4c7 // indirect google.golang.org/grpc v1.65.0 // indirect google.golang.org/protobuf v1.35.1 // indirect gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect gopkg.in/inf.v0 v0.9.1 // indirect gopkg.in/yaml.v3 v3.0.1 // indirect k8s.io/apiextensions-apiserver v0.32.1 // indirect k8s.io/apiserver v0.32.1 // indirect k8s.io/component-base v0.32.1 // indirect k8s.io/klog/v2 v2.130.1 // indirect k8s.io/kube-openapi v0.0.0-20241105132330-32ad38e42d3f // indirect k8s.io/utils v0.0.0-20241104100929-3ea5e8cea738 // indirect sigs.k8s.io/apiserver-network-proxy/konnectivity-client v0.31.0 // indirect sigs.k8s.io/json v0.0.0-20241010143419-9aa6b5e7a4b3 // indirect sigs.k8s.io/structured-merge-diff/v4 v4.4.2 // indirect sigs.k8s.io/yaml v1.4.0 // indirect )
Makefile: Make targets for building and deploying your controller
# Image URL to use all building/pushing image targets IMG ?= controller:latest # 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 # 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) CONTAINER_TOOL ?= docker # 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 .SHELLFLAGS = -ec .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($$0, 5) } ' $(MAKEFILE_LIST) ##@ Development .PHONY: manifests manifests: controller-gen ## Generate WebhookConfiguration, ClusterRole and CustomResourceDefinition objects. # Note that the option maxDescLen=0 was added in the default scaffold in order to sort out the issue # Too long: must have at most 262144 bytes. By using kubectl apply to create / update resources an annotation # is created by K8s API to store the latest version of the resource ( kubectl.kubernetes.io/last-applied-configuration). # However, it has a size limit and if the CRD is too big with so many long descriptions as this one it will cause the failure. $(CONTROLLER_GEN) rbac:roleName=manager-role crd:maxDescLen=0 webhook paths="./..." output:crd:artifacts:config=config/crd/bases .PHONY: generate generate: controller-gen ## Generate code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations. $(CONTROLLER_GEN) object:headerFile="hack/boilerplate.go.txt" paths="./..." .PHONY: fmt fmt: ## Run go fmt against code. go fmt ./... .PHONY: vet vet: ## Run go vet against code. go vet ./... .PHONY: test test: manifests generate fmt vet setup-envtest ## Run tests. KUBEBUILDER_ASSETS="$(shell $(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path)" go test $$(go list ./... | grep -v /e2e) -coverprofile cover.out # TODO(user): To use a different vendor for e2e tests, modify the setup under 'tests/e2e'. # The default setup assumes Kind is pre-installed and builds/loads the Manager Docker image locally. # CertManager is installed by default; skip with: # - CERT_MANAGER_INSTALL_SKIP=true KIND_CLUSTER ?= project-test-e2e .PHONY: setup-test-e2e setup-test-e2e: ## Set up a Kind cluster for e2e tests if it does not exist @command -v $(KIND) >/dev/null 2>&1 || { \ echo "Kind is not installed. Please install Kind manually."; \ exit 1; \ } $(KIND) create cluster --name $(KIND_CLUSTER) .PHONY: test-e2e test-e2e: setup-test-e2e manifests generate fmt vet ## Run the e2e tests. Expected an isolated environment using Kind. KIND_CLUSTER=$(KIND_CLUSTER) go test ./test/e2e/ -v -ginkgo.v $(MAKE) cleanup-test-e2e .PHONY: cleanup-test-e2e cleanup-test-e2e: ## Tear down the Kind cluster used for e2e tests @$(KIND) delete cluster --name $(KIND_CLUSTER) .PHONY: lint lint: golangci-lint ## Run golangci-lint linter $(GOLANGCI_LINT) run .PHONY: lint-fix lint-fix: golangci-lint ## Run golangci-lint linter and perform fixes $(GOLANGCI_LINT) run --fix .PHONY: lint-config lint-config: golangci-lint ## Verify golangci-lint linter configuration $(GOLANGCI_LINT) config verify ##@ 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. $(CONTAINER_TOOL) push ${IMG} # PLATFORMS defines the target platforms for the manager image be built to provide support to multiple # architectures. (i.e. make docker-buildx IMG=myregistry/mypoperator:0.0.1). To use this option you need to: # - be able to use docker buildx. More info: https://docs.docker.com/build/buildx/ # - have enabled BuildKit. More info: https://docs.docker.com/develop/develop-images/build_enhancements/ # - be able to push the image to your registry (i.e. if you do not set a valid value via IMG=<myregistry/image:<tag>> then the export will fail) # To adequately provide solutions that are compatible with multiple platforms, you should consider using this option. PLATFORMS ?= linux/arm64,linux/amd64,linux/s390x,linux/ppc64le .PHONY: docker-buildx docker-buildx: ## Build and push docker image for the manager for cross-platform support # copy existing Dockerfile and insert --platform=${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-builder $(CONTAINER_TOOL) buildx use project-builder - $(CONTAINER_TOOL) buildx build --push --platform=$(PLATFORMS) --tag ${IMG} -f Dockerfile.cross . - $(CONTAINER_TOOL) buildx rm project-builder rm Dockerfile.cross .PHONY: build-installer build-installer: manifests generate kustomize ## Generate a consolidated YAML with CRDs and deployment. mkdir -p dist cd config/manager && $(KUSTOMIZE) edit set image controller=${IMG} $(KUSTOMIZE) build config/default > dist/install.yaml ##@ Deployment ifndef ignore-not-found ignore-not-found = false endif .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: kustomize ## 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 - ##@ Dependencies ## Location to install dependencies to LOCALBIN ?= $(shell pwd)/bin $(LOCALBIN): mkdir -p $(LOCALBIN) ## Tool Binaries KUBECTL ?= kubectl KIND ?= kind KUSTOMIZE ?= $(LOCALBIN)/kustomize CONTROLLER_GEN ?= $(LOCALBIN)/controller-gen ENVTEST ?= $(LOCALBIN)/setup-envtest GOLANGCI_LINT = $(LOCALBIN)/golangci-lint ## Tool Versions KUSTOMIZE_VERSION ?= v5.6.0 CONTROLLER_TOOLS_VERSION ?= v0.18.0 #ENVTEST_VERSION is the version of controller-runtime release branch to fetch the envtest setup script (i.e. release-0.20) ENVTEST_VERSION ?= $(shell go list -m -f "{{ .Version }}" sigs.k8s.io/controller-runtime | awk -F'[v.]' '{printf "release-%d.%d", $$2, $$3}') #ENVTEST_K8S_VERSION is the version of Kubernetes to use for setting up ENVTEST binaries (i.e. 1.31) ENVTEST_K8S_VERSION ?= $(shell go list -m -f "{{ .Version }}" k8s.io/api | awk -F'[v.]' '{printf "1.%d", $$3}') GOLANGCI_LINT_VERSION ?= v2.1.0 .PHONY: kustomize kustomize: $(KUSTOMIZE) ## Download kustomize locally if necessary. $(KUSTOMIZE): $(LOCALBIN) $(call go-install-tool,$(KUSTOMIZE),sigs.k8s.io/kustomize/kustomize/v5,$(KUSTOMIZE_VERSION)) .PHONY: controller-gen controller-gen: $(CONTROLLER_GEN) ## Download controller-gen locally if necessary. $(CONTROLLER_GEN): $(LOCALBIN) $(call go-install-tool,$(CONTROLLER_GEN),sigs.k8s.io/controller-tools/cmd/controller-gen,$(CONTROLLER_TOOLS_VERSION)) .PHONY: setup-envtest setup-envtest: envtest ## Download the binaries required for ENVTEST in the local bin directory. @echo "Setting up envtest binaries for Kubernetes version $(ENVTEST_K8S_VERSION)..." @$(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path || { \ echo "Error: Failed to set up envtest binaries for version $(ENVTEST_K8S_VERSION)."; \ exit 1; \ } .PHONY: envtest envtest: $(ENVTEST) ## Download setup-envtest locally if necessary. $(ENVTEST): $(LOCALBIN) $(call go-install-tool,$(ENVTEST),sigs.k8s.io/controller-runtime/tools/setup-envtest,$(ENVTEST_VERSION)) .PHONY: golangci-lint golangci-lint: $(GOLANGCI_LINT) ## Download golangci-lint locally if necessary. $(GOLANGCI_LINT): $(LOCALBIN) $(call go-install-tool,$(GOLANGCI_LINT),github.com/golangci/golangci-lint/v2/cmd/golangci-lint,$(GOLANGCI_LINT_VERSION)) # go-install-tool will 'go install' any package with custom target and name of binary, if it doesn't exist # $1 - target path with name of binary # $2 - package url which can be installed # $3 - specific version of package define go-install-tool @[ -f "$(1)-$(3)" ] || { \ set -e; \ package=$(2)@$(3) ;\ echo "Downloading $${package}" ;\ rm -f $(1) || true ;\ GOBIN=$(LOCALBIN) go install $${package} ;\ mv $(1) $(1)-$(3) ;\ } ;\ ln -sf $(1)-$(3) $(1) endef
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 cliVersion: (devel) domain: tutorial.kubebuilder.io layout: - go.kubebuilder.io/v4 plugins: helm.kubebuilder.io/v1-alpha: {} projectName: project repo: tutorial.kubebuilder.io/project resources: - api: crdVersion: v1 namespaced: true controller: true domain: tutorial.kubebuilder.io group: batch kind: CronJob path: tutorial.kubebuilder.io/project/api/v1 version: v1 webhooks: 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…