1. What is a Makefile
In software development, a Makefile is a script file used for automating the build and management of projects, typically used in conjunction with the make tool. Its core objective is to automate tasks such as compilation, testing, packaging, and deployment. Makefile standardizes commands through declarative rules and dependencies, unifying the development process, reducing collaboration costs, and enhancing R&D efficiency (cost reduction and efficiency improvement).
2. Makefile Syntax Rules
2.1 Basic Structure
A Makefile contains a series of rules, each defining how to generate a target file (such as an executable or library) from source files. A rule consists of three parts, illustrated by an example rule from the Makefile to be interpreted below.
% make help
make: *** No rule to make target `help'. Stop.
.PHONY: manifests
manifests: controller-gen ## Generate WebhookConfiguration, ClusterRole and CustomResourceDefinition objects.
$(CONTROLLER_GEN) rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases
- Target:The name of the file to be generated or the task to be executed.manifests is the target of this rule, indicating the name of the task to be executed..PHONY: manifests: declares manifests as a phony target, meaning that even if a file with the same name exists, make will forcefully execute this command.
- Dependencies:The files or other targets required to generate the target.controller-gen is a dependency of the target, indicating that it must be ready before executing manifests.
- Commands:The specific shell commands to be executed (must start with a Tab).$(CONTROLLER_GEN) rbac:roleName=manager-role crd webhook paths=”./…” output:crd:artifacts:config=config/crd/bases is the actual command executed to generate the corresponding resources.
2.2 Comments
Lines starting with # are comments.
2.3 Variables
Defining variables: =, :=, and ?=.Using variables:$, such as $(CONTROLLER_GEN).
2.4 Phony Targets
These are special targets indicating that the target is not an actual file name, typically used to perform certain operations or tasks, such as cleaning up build files or running tests.
Other syntax also supports functions (custom functions), conditional statements, pattern rules, etc. (details omitted).
3. Interpreting the Makefile
The Makefile referenced in this article is provided by the kubebuilder tool and will also be used in K8s Operator development.
# Image URL to use all building/pushing image targets
IMG ?= controller:latest
# Get the currently used golang install path (in GOPATH/bin, unless GOBIN is set)
ifeq (,$(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($$0, 5) } ' $(MAKEFILE_LIST)
##@ Development
.PHONY: manifests
manifests: controller-gen ## Generate WebhookConfiguration, ClusterRole and CustomResourceDefinition objects.
$(CONTROLLER_GEN) rbac:roleName=manager-role crd webhook paths="./..." output:crd:artifacts:config=config/crd/bases
.PHONY: generate
generate: controller-gen ## Generate code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations.
$(CONTROLLER_GEN) object:headerFile="hack/boilerplate.go.txt" paths="./..."
.PHONY: fmt
fmt: ## Run go fmt against code.
go fmt ./...
.PHONY: vet
vet: ## Run go vet against code.
go vet ./...
.PHONY: test
test: manifests generate fmt vet setup-envtest ## Run tests.
KUBEBUILDER_ASSETS="$(shell $(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path)" go test $$(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
.PHONY: test-e2e
test-e2e: manifests generate fmt vet ## Run the e2e tests. Expected an isolated environment using Kind.
@command -v kind >/dev/null 2>&1 || {
echo "Kind is not installed. Please install Kind manually.";
exit 1;
}
@kind get clusters | grep -q 'kind' || {
echo "No Kind cluster is running. Please start a Kind cluster before running the e2e tests.";
exit 1;
}
go test ./test/e2e/ -v -ginkgo.v
.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 op2-builder
$(CONTAINER_TOOL) buildx use op2-builder
- $(CONTAINER_TOOL) buildx build --push --platform=$(PLATFORMS) --tag ${IMG} -f Dockerfile.cross .
- $(CONTAINER_TOOL) buildx rm op2-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
KUSTOMIZE ?= $(LOCALBIN)/kustomize
CONTROLLER_GEN ?= $(LOCALBIN)/controller-gen
ENVTEST ?= $(LOCALBIN)/setup-envtest
GOLANGCI_LINT = $(LOCALBIN)/golangci-lint
## Tool Versions
KUSTOMIZE_VERSION ?= v5.5.0
CONTROLLER_TOOLS_VERSION ?= v0.17.2
#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", $$3}')
GOLANGCI_LINT_VERSION ?= v1.63.4
.PHONY: kustomize
kustomize: $(KUSTOMIZE) ## Download kustomize locally if necessary.
$(KUSTOMIZE): $(LOCALBIN)
$(call go-install-tool,$(KUSTOMIZE),sigs.k8s.io/kustomize/kustomize/v5,$(KUSTOMIZE_VERSION))
.PHONY: controller-gen
controller-gen: $(CONTROLLER_GEN) ## Download controller-gen locally if necessary.
$(CONTROLLER_GEN): $(LOCALBIN)
$(call go-install-tool,$(CONTROLLER_GEN),sigs.k8s.io/controller-tools/cmd/controller-gen,$(CONTROLLER_TOOLS_VERSION))
.PHONY: setup-envtest
setup-envtest: envtest ## Download the binaries required for ENVTEST in the local bin directory.
@echo "Setting up envtest binaries for Kubernetes version $(ENVTEST_K8S_VERSION)..."
@$(ENVTEST) use $(ENVTEST_K8S_VERSION) --bin-dir $(LOCALBIN) -p path || { \
echo "Error: Failed to set up envtest binaries for version $(ENVTEST_K8S_VERSION)."; \
exit 1; \
}
.PHONY: envtest
envtest: $(ENVTEST) ## Download setup-envtest locally if necessary.
$(ENVTEST): $(LOCALBIN)
$(call go-install-tool,$(ENVTEST),sigs.k8s.io/controller-runtime/tools/setup-envtest,$(ENVTEST_VERSION))
.PHONY: golangci-lint
golangci-lint: $(GOLANGCI_LINT) ## Download golangci-lint locally if necessary.
$(GOLANGCI_LINT): $(LOCALBIN)
$(call go-install-tool,$(GOLANGCI_LINT),github.com/golangci/golangci-lint/cmd/golangci-lint,$(GOLANGCI_LINT_VERSION))
# go-install-tool will 'go install' any package with custom target and name of binary, if it doesn't exist
# $1 - target path with name of binary
# $2 - package url which can be installed
# $3 - specific version of package
define go-install-tool
@[ -f "$(1)-$(3)" ] || { \
set -e; \
package=$(2)@$(3) ;\
echo "Downloading $${package}" ;\
rm -f $(1) || true ;\
GOBIN=$(LOCALBIN) go install $${package} ;\
mv $(1) $(1)-$(3) ;\
} ;\
ln -sf $(1)-$(3) $(1)
endef
This Makefile includes two main parts: variable definitions and target definitions (general targets, development-related targets, build-related targets, deployment-related targets, and dependency management targets).
% make help
Usage:
make <target>
General
help Display this help.
Development
manifests Generate WebhookConfiguration, ClusterRole and CustomResourceDefinition objects.
generate Generate code containing DeepCopy, DeepCopyInto, and DeepCopyObject method implementations.
fmt Run go fmt against code.
vet Run go vet against code.
test Run tests.
test-e2e Run the e2e tests. Expected an isolated environment using Kind.
lint Run golangci-lint linter
lint-fix Run golangci-lint linter and perform fixes
lint-config Verify golangci-lint linter configuration
Build
build Build manager binary.
run Run a controller from your host.
docker-build Build docker image with the manager.
docker-push Push docker image with the manager.
docker-buildx Build and push docker image for the manager for cross-platform support
build-installer Generate a consolidated YAML with CRDs and deployment.
Deployment
install Install CRDs into the K8s cluster specified in ~/.kube/config.
uninstall Uninstall CRDs from the K8s cluster specified in ~/.kube/config. Call with ignore-not-found=true to ignore resource not found errors during deletion.
deploy Deploy controller to the K8s cluster specified in ~/.kube/config.
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.
Dependencies
kustomize Download kustomize locally if necessary.
controller-gen Download controller-gen locally if necessary.
setup-envtest Download the binaries required for ENVTEST in the local bin directory.
envtest Download setup-envtest locally if necessary.