Compress k0s binary using UPX

Make this configurable via Make variables.

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

Makefile

@@ -45,6 +45,9 @@ else
   GO ?= $(GO_ENV) go
 endif
 
+UPX ?= upx
+UPX_OPTS ?= -1
+
 # EMBEDDED_BINS_BUILDMODE can be either:
 #   docker	builds the binaries in docker
 #   none	does not embed any binaries
@@ -203,6 +206,9 @@ k0s.exe: BUILD_GO_CGO_ENABLED = 0
 k0s.exe k0s: $(GO_ENV_REQUISITES) go.sum $(codegen_targets) $(GO_SRCS) $(shell find static/manifests/calico static/manifests/windows -type f)
 	rm -f -- '$@'
 	CGO_ENABLED=$(BUILD_GO_CGO_ENABLED) CGO_CFLAGS='$(BUILD_CGO_CFLAGS)' GOOS=$(TARGET_OS) $(GO) build $(BUILD_GO_FLAGS) -ldflags='$(LD_FLAGS)' -o '$@' main.go
+ifneq ($(UPX),)
+	$(GO_ENV) $(UPX) $(UPX_OPTS) -- '$@'
+endif
 ifneq ($(EMBEDDED_BINS_BUILDMODE),none)
 	cat -- bindata_$(TARGET_OS) >>$@
 endif

build/Dockerfile

@@ -9,7 +9,7 @@ RUN set -ex; \
   arm*) binutils=binutils-gold ;; \
     *)    binutils=binutils ;; \
   esac; \
-  apk add --no-cache make gcc musl-dev "$binutils"
+  apk add --no-cache make gcc musl-dev "$binutils" upx
 
 ENV \
   HOME="/run/k0s-build" \