Minor build improvements

Makefile

* Make Go build flags parameterizable
  * Verbose by default
  * Do not force complete rebuild
  * Remove unnecessary '-installsuffix' flag
    https://plus.google.com/117192131596509381660/posts/eNnNePihYnK
* Log build steps
* Rename 'clean' target to 'clean-container'
* Move artifact copy to '.container' target
* Add 'clean' target

Shell script

* Fix shellcheck SC2068
  https://github.com/koalaman/shellcheck/wiki/SC2068
* Reject mandatory vars with empty values

Makefile

@@ -48,6 +48,8 @@ ARCH ?= $(shell go env GOARCH)
 GOARCH = ${ARCH}
 DUMB_ARCH = ${ARCH}
 
+GOBUILD_FLAGS :=
+
 ALL_ARCH = amd64 arm arm64 ppc64le s390x
 
 QEMUVERSION = v2.12.0
@@ -80,7 +82,7 @@ endif
 
 TEMP_DIR := $(shell mktemp -d)
 
-DEF_VARS:=ARCH=$(ARCH)       \
+DEF_VARS:=ARCH=$(ARCH)           \
 	TAG=$(TAG)               \
 	PKG=$(PKG)               \
 	GOARCH=$(GOARCH)         \
@@ -109,10 +111,15 @@ all-container: $(addprefix sub-container-,$(ALL_ARCH))
 all-push: $(addprefix sub-push-,$(ALL_ARCH))
 
 .PHONY: container
-container: .container-$(ARCH)
+container: clean-container .container-$(ARCH)
 
 .PHONY: .container-$(ARCH)
 .container-$(ARCH):
+	@echo "+ Copying artifact to temporary directory"
+	mkdir -p $(TEMP_DIR)/rootfs
+	cp bin/$(ARCH)/nginx-ingress-controller $(TEMP_DIR)/rootfs/nginx-ingress-controller
+
+	@echo "+ Building container image $(MULTI_ARCH_IMG):$(TAG)"
 	cp -RP ./* $(TEMP_DIR)
 	$(SED_I) "s|BASEIMAGE|$(BASEIMAGE)|g" $(DOCKERFILE)
 	$(SED_I) "s|QEMUARCH|$(QEMUARCH)|g" $(DOCKERFILE)
@@ -134,6 +141,11 @@ ifeq ($(ARCH), amd64)
 	$(DOCKER) tag $(MULTI_ARCH_IMG):$(TAG) $(IMAGE):$(TAG)
 endif
 
+.PHONY: clean-container
+clean-container:
+	@echo "+ Deleting container image $(MULTI_ARCH_IMG):$(TAG)"
+	$(DOCKER) rmi -f $(MULTI_ARCH_IMG):$(TAG) || true
+
 .PHONY: register-qemu
 register-qemu:
 	# Register /usr/bin/qemu-ARCH-static as the handler for binaries in multiple platforms
@@ -149,17 +161,16 @@ ifeq ($(ARCH), amd64)
 	$(DOCKER) push $(IMAGE):$(TAG)
 endif
 
-.PHONY: clean
-clean:
-	$(DOCKER) rmi -f $(MULTI_ARCH_IMG):$(TAG) || true
-
 .PHONY: build
-build: clean
+build:
+	@echo "+ Building bin/$(ARCH)/nginx-ingress-controller"
 	@$(DEF_VARS) \
+	GOBUILD_FLAGS="$(GOBUILD_FLAGS)" \
 	build/go-in-docker.sh build/build.sh
 
-	mkdir -p $(TEMP_DIR)/rootfs
-	cp bin/$(ARCH)/nginx-ingress-controller $(TEMP_DIR)/rootfs/nginx-ingress-controller
+.PHONY: clean
+clean:
+	rm -rf bin/ .gocache/ .env
 
 .PHONY: static-check
 static-check:

build/build.sh

@@ -28,20 +28,21 @@ mandatory=(
 )
 
 missing=false
-for var in ${mandatory[@]}; do
-  if [[ -z "${!var+x}" ]]; then
+for var in "${mandatory[@]}"; do
+  if [[ -z "${!var:-}" ]]; then
     echo "Environment variable $var must be set"
     missing=true
   fi
 done
 
-if [ "$missing" = true ];then
+if [ "$missing" = true ]; then
   exit 1
 fi
 
 export CGO_ENABLED=0
 
-go build -a -installsuffix cgo 	\
+go build \
+    ${GOBUILD_FLAGS} \
     -ldflags "-s -w \
         -X ${PKG}/version.RELEASE=${TAG} \
         -X ${PKG}/version.COMMIT=${GIT_COMMIT} \

build/go-in-docker.sh

@@ -56,6 +56,7 @@ TAG=${TAG:-"0.0"}
 HOME=${HOME:-/root}
 KUBECONFIG=${HOME}/.kube/config
 GOARCH=${GOARCH}
+GOBUILD_FLAGS=${GOBUILD_FLAGS:-"-v"}
 PWD=${PWD}
 BUSTED_ARGS=${BUSTED_ARGS:-""}
 REPO_INFO=${REPO_INFO:-local}