Introduce K0S_BUILDMODE Makefile variable

Allow to select how to build k0s, similar to what
EMBEDDED_BIND_BUILDMODE is doing for the embedded binaries. The two
supported values are "docker", which is the default and builds k0s the
usual way, and "host", which bypasses Docker and uses the toolchains
present on the host system.

Doing this was already partly possible via `make GO_ENV=''`, but this
still called out to Docker to build the k0s build image and for the
codegen tasks.

The K0S_BUILDMODE variable bypasses Docker correctly for all
make requisites of k0s, including codegen. Note that this doesn't
impact the embedded binaries, so they need to be skipped via
EMBEDDED_BIND_BUILDMODE=none to have a completely Docker-free build.

This allows for building and testing k0s on systems that don't have
Docker, or on architectures for which there are no appropriate Docker
images available.

Signed-off-by: Tom Wieczorek <[email protected]>

.github/workflows/go.yml

@@ -189,12 +189,10 @@ jobs:
 
       - name: Run unit tests
         env:
-          EMBEDDED_BINS_BUILDMODE: none
           TARGET_OS: windows
-          GO: go
-          GO_ENV: ''
+          K0S_BUILDMODE: host
+          EMBEDDED_BINS_BUILDMODE: none
         run: |
-          make --touch .k0sbuild.docker-image.k0s go.sum
           make bindata
           make --touch codegen
           make check-unit

Makefile

@@ -21,11 +21,16 @@ K0S_GO_BUILD_CACHE ?= build/cache
 GO_SRCS := $(shell find . -type f -name '*.go' -not -path './$(K0S_GO_BUILD_CACHE)/*' -not -path './inttest/*' -not -name '*_test.go' -not -name 'zz_generated*')
 GO_CHECK_UNIT_DIRS := . ./cmd/... ./pkg/... ./internal/... ./static/... ./hack/...
 
-# EMBEDDED_BINS_BUILDMODE can be either:
-#   docker	builds the binaries in docker
-#   none	does not embed any binaries
+# K0S_BUILDMODE can be either:
+#   docker   builds k0s in Docker
+#   host     builds k0s using the host's toolchains
+K0S_BUILDMODE ?= docker
 
+# EMBEDDED_BINS_BUILDMODE can be either:
+#   docker   builds the embedded binaries in Docker
+#   none     does not embed any binaries
 EMBEDDED_BINS_BUILDMODE ?= docker
+
 # k0s runs on linux even if it's built on mac or windows
 TARGET_OS ?= linux
 BUILD_UID ?= $(shell id -u)
@@ -49,6 +54,33 @@ else
 	BUILD_DATE ?= $(shell TZ=UTC git log -1 --pretty=%cd --date='format-local:$(BUILD_DATE_FMT)' || date -u +$(BUILD_DATE_FMT))
 endif
 
+GOLANG_IMAGE ?= $(golang_buildimage)
+
+ifeq ($(K0S_BUILDMODE), docker)
+k0s_buildmode_requisites = .k0sbuild.docker-image.k0s
+K0S_GO_BUILD_CACHE_VOLUME_PATH ?= $(realpath $(K0S_GO_BUILD_CACHE))
+GO_ENV ?= docker run --rm \
+	-v '$(K0S_GO_BUILD_CACHE_VOLUME_PATH)':/run/k0s-build \
+	-v '$(CURDIR)':/go/src/github.com/k0sproject/k0s \
+	-w /go/src/github.com/k0sproject/k0s \
+	-e GOOS \
+	-e CGO_ENABLED \
+	-e GOARCH \
+	--user $(BUILD_UID):$(BUILD_GID) \
+	-- '$(shell cat .k0sbuild.docker-image.k0s)'
+else ifeq ($(K0S_BUILDMODE), host)
+k0s_buildmode_requisites =
+GO_ENV ?=
+else
+$(error Unknown value for K0S_BUILDMODE: $(K0S_BUILDMODE))
+endif
+
+ifeq (, $(filter $(EMBEDDED_BINS_BUILDMODE), docker none))
+$(error Unknown value for EMBEDDED_BINS_BUILDMODE: $(EMBEDDED_BINS_BUILDMODE))
+endif
+
+GO ?= $(GO_ENV) go
+
 LD_FLAGS += -X github.com/k0sproject/k0s/pkg/build.Version=$(VERSION)
 LD_FLAGS += -X github.com/k0sproject/k0s/pkg/build.RuncVersion=$(runc_version)
 LD_FLAGS += -X github.com/k0sproject/k0s/pkg/build.ContainerdVersion=$(containerd_version)
@@ -71,19 +103,6 @@ endif
 endif
 LD_FLAGS += $(BUILD_GO_LDFLAGS_EXTRA)
 
-GOLANG_IMAGE ?= $(golang_buildimage)
-K0S_GO_BUILD_CACHE_VOLUME_PATH=$(realpath $(K0S_GO_BUILD_CACHE))
-GO_ENV ?= docker run --rm \
-	-v '$(K0S_GO_BUILD_CACHE_VOLUME_PATH)':/run/k0s-build \
-	-v '$(CURDIR)':/go/src/github.com/k0sproject/k0s \
-	-w /go/src/github.com/k0sproject/k0s \
-	-e GOOS \
-	-e CGO_ENABLED \
-	-e GOARCH \
-	--user $(BUILD_UID):$(BUILD_GID) \
-	-- '$(shell cat .k0sbuild.docker-image.k0s)'
-GO ?= $(GO_ENV) go
-
 # https://www.gnu.org/software/make/manual/make.html#index-spaces_002c-in-variable-values
 nullstring :=
 space := $(nullstring) # space now holds a single space
@@ -110,7 +129,7 @@ $(K0S_GO_BUILD_CACHE):
 	  --build-arg BUILDIMAGE=$(GOLANG_IMAGE) \
 	  -t k0sbuild.docker-image.k0s - <build/Dockerfile
 
-go.sum: go.mod .k0sbuild.docker-image.k0s
+go.sum: go.mod $(k0s_buildmode_requisites)
 	$(GO) mod tidy && touch -c -- '$@'
 
 codegen_targets += pkg/apis/helm/v1beta1/.controller-gen.stamp
@@ -125,7 +144,7 @@ codegen_targets += pkg/apis/autopilot/v1beta2/.controller-gen.stamp
 pkg/apis/autopilot/v1beta2/.controller-gen.stamp: $(shell find pkg/apis/autopilot/v1beta2/ -maxdepth 1 -type f -name \*.go)
 pkg/apis/autopilot/v1beta2/.controller-gen.stamp: gen_output_dir = autopilot
 
-pkg/apis/%/.controller-gen.stamp: .k0sbuild.docker-image.k0s hack/tools/boilerplate.go.txt hack/tools/Makefile.variables
+pkg/apis/%/.controller-gen.stamp: $(k0s_buildmode_requisites) hack/tools/boilerplate.go.txt hack/tools/Makefile.variables
 	rm -rf 'static/manifests/$(gen_output_dir)/CustomResourceDefinition'
 	rm -f -- '$(dir $@)'zz_*.go
 	CGO_ENABLED=0 $(GO) install sigs.k8s.io/controller-tools/cmd/controller-gen@v$(controller-gen_version)
@@ -139,7 +158,7 @@ pkg/apis/%/.controller-gen.stamp: .k0sbuild.docker-image.k0s hack/tools/boilerpl
 clientset_input_dirs := pkg/apis/autopilot/v1beta2 pkg/apis/k0s/v1beta1
 codegen_targets += pkg/client/clientset/.client-gen.stamp
 pkg/client/clientset/.client-gen.stamp: $(shell find $(clientset_input_dirs) -type f -name \*.go -not -name \*_test.go -not -name zz_\*)
-pkg/client/clientset/.client-gen.stamp: .k0sbuild.docker-image.k0s hack/tools/boilerplate.go.txt embedded-bins/Makefile.variables
+pkg/client/clientset/.client-gen.stamp: $(k0s_buildmode_requisites) hack/tools/boilerplate.go.txt embedded-bins/Makefile.variables
 	rm -rf -- '$(dir $@)'
 	CGO_ENABLED=0 $(GO) run k8s.io/code-generator/cmd/client-gen@v$(kubernetes_version:1.%=0.%) \
 	  --go-header-file=hack/tools/boilerplate.go.txt \
@@ -153,7 +172,7 @@ pkg/client/clientset/.client-gen.stamp: .k0sbuild.docker-image.k0s hack/tools/bo
 
 codegen_targets += static/zz_generated_assets.go
 static_asset_dirs := static/manifests static/misc
-static/zz_generated_assets.go: .k0sbuild.docker-image.k0s hack/tools/Makefile.variables
+static/zz_generated_assets.go: $(k0s_buildmode_requisites) hack/tools/Makefile.variables
 static/zz_generated_assets.go: $(shell find $(static_asset_dirs) -type f)
 	-rm -f -- '$@'
 	CGO_ENABLED=0 $(GO) install github.com/kevinburke/go-bindata/go-bindata@v$(go-bindata_version)
@@ -172,7 +191,7 @@ pkg/assets/zz_generated_offsets_linux.go pkg/assets/zz_generated_offsets_windows
 else
 pkg/assets/zz_generated_offsets_linux.go: .bins.linux.stamp
 pkg/assets/zz_generated_offsets_windows.go: .bins.windows.stamp
-pkg/assets/zz_generated_offsets_linux.go pkg/assets/zz_generated_offsets_windows.go: .k0sbuild.docker-image.k0s go.sum
+pkg/assets/zz_generated_offsets_linux.go pkg/assets/zz_generated_offsets_windows.go: $(k0s_buildmode_requisites) go.sum
 	GOOS=${GOHOSTOS} $(GO) run -tags=hack hack/gen-bindata/cmd/main.go -o bindata_$(zz_os) -pkg assets \
 	     -gofile pkg/assets/zz_generated_offsets_$(zz_os).go \
 	     -prefix embedded-bins/staging/$(zz_os)/ embedded-bins/staging/$(zz_os)/bin
@@ -184,7 +203,7 @@ pkg/assets/zz_generated_offsets_darwin.go:
 
 k0s: TARGET_OS = linux
 k0s: BUILD_GO_CGO_ENABLED = 1
-k0s: .k0sbuild.docker-image.k0s
+k0s: $(k0s_buildmode_requisites)
 
 k0s.exe: TARGET_OS = windows
 k0s.exe: BUILD_GO_CGO_ENABLED = 0
@@ -213,14 +232,14 @@ lint-copyright:
 
 .PHONY: lint-go
 lint-go: GOLANGCI_LINT_FLAGS ?=
-lint-go: .k0sbuild.docker-image.k0s go.sum codegen
+lint-go: $(k0s_buildmode_requisites) go.sum codegen
 	CGO_ENABLED=0 $(GO) install github.com/golangci/golangci-lint/cmd/golangci-lint@v$(golangci-lint_version)
 	$(GO_ENV) golangci-lint run --verbose $(GOLANGCI_LINT_FLAGS) $(GO_LINT_DIRS)
 
 .PHONY: lint
 lint: lint-copyright lint-go
 
-airgap-images.txt: k0s .k0sbuild.docker-image.k0s
+airgap-images.txt: k0s $(k0s_buildmode_requisites)
 	$(GO_ENV) ./k0s airgap list-images --all > '$@'
 
 airgap-image-bundle-linux-amd64.tar: TARGET_PLATFORM := linux/amd64