Add tag target and generally clean-up Makefile

Author: Martin Baillie

Makefile

@@ -1,52 +1,107 @@
-SHELL 	:= /bin/bash
+SHELL 		:=$(shell which bash)
+.SHELLFLAGS =-c
+
+ifndef DEBUG
+.SILENT: ;
+endif
+.EXPORT_ALL_VARIABLES: ;
+
+WORKDIR 	=$(patsubst %/,%,$(dir $(realpath $(lastword $(MAKEFILE_LIST)))))
+PROJECT 	=$(notdir $(WORKDIR))
+
 DIR 	:=$(shell pwd)
 TIME 	:=$(shell date '+%Y-%m-%dT%T%z')
+GPG_KEY ?=$(shell git config user.signingkey)
 
 SRC 		?=$(shell go list ./...)
-SRCFILES	?=$(shell find . -type f -name '*.go' -not -path './vendor/*')
+SRCFILES	?=$(shell find . -type f -name '*.go')
 
 LDFLAGS ?=-s -w -extld ld -extldflags -static
 FLAGS	?=-a -installsuffix cgo -ldflags "$(LDFLAGS)"
-GOOS 	?=darwin windows linux
-GOARCH 	?=amd64
 
-PROJECT	?=packer-post-processor-ami-copy
+GOVERS 		=$(shell go version)
+GOOS		=$(word 1,$(subst /, ,$(lastword $(GOVERS))))
+GOARCH		=$(word 2,$(subst /, ,$(lastword $(GOVERS))))
+GOOSES		=darwin linux windows
+GOARCHES 	=amd64
 
 .DEFAULT_GOAL := build
 
-.PHONY: clean fix fmt generate test build help
+.PHONY: clean fix fmt generate test build tag help
 
-clean:: ## Removes binary and generated files
-	@echo ">> cleaning"
-	@rm -rf $(PROJECT)* 
+clean: ## Removes binary and generated files
+	echo >&2 ">> cleaning"
+	rm -rf $(PROJECT)*
 
-fix:: ## Runs the Golang fix tool
-	@echo ">> fixing"
-	@go fix $(SRC)
+fix: ## Runs the Golang fix tool
+	echo >&2 ">> fixing"
+	go fix $(SRC)
 
-fmt:: ## Formats source code according to the Go standard
-	@echo ">> formatting"
-	@gofmt -w -s -l $(SRCFILES)
+fmt: ## Formats source code according to the Go standard
+	echo >&2 ">> formatting"
+	gofmt -w -s -l $(SRCFILES)
 
-generate:: ## Runs the Golang generate tool
-	@echo ">> generating"
-	@go install github.com/hashicorp/packer/cmd/mapstructure-to-hcl2
-	@go generate ./...
+generate: ## Runs the Golang generate tool
+	echo >&2 ">> generating"
+	go install github.com/hashicorp/packer/cmd/mapstructure-to-hcl2
+	go generate ./...
 
 test: clean fix fmt generate
 
-build:: test ## Builds for all arch ($GOARCH) and OS ($GOOS)
-	@echo ">> building"
-	@for arch in ${GOARCH}; do \
-		for os in ${GOOS}; do \
-			echo ">>>> $${os}/$${arch}"; \
-			env GOOS=$${os} GOARCH=$${arch} \
-			CGO_ENABLED=0 go build $(FLAGS) \
-			-o $(PROJECT)-$${os}-$${arch}; \
-		done; \
-	done
+# Create a cross-compile target for every os/arch pairing. This will generate a
+# non-phony make target for each os/arch pair as well as a phony meta target
+# (build) for compiling everything.
+_build:
+	echo >&2 ">> building"
+.PHONY: _build
+define build-target
+  $(PROJECT)-$(1)-$(2)$(3):
+  ifeq (,$(findstring $(1)-$(2),$(NOARCHES)))
+		echo >&2 ">>>> $$@"
+		env GOOS=$(1) GOARCH=$(2) CGO_ENABLED=0 go build $(FLAGS) -o $$@
+  endif
+
+  build: _build $(PROJECT)-$(1)-$(2)$(3)
+endef
+$(foreach goarch,$(GOARCHES), \
+	$(foreach goos,$(GOOSES), \
+		$(eval \
+			$(call build-target,$(goos),$(goarch),$(if \
+				$(findstring windows,$(goos)),.exe,)\
+			) \
+		) \
+	) \
+)
+build: ## Build for every supported OS and arch combination
+.PHONY: build
+
+tag: ## Create a signed commit and tag
+	echo >&2 ">> tagging"
+	if [[ ! $(VERSION) =~ ^[0-9]+[.][0-9]+([.][0.9]*)?$  ]]; then \
+		echo >&2 "ERROR: VERSION ($(VERSION)) is not a semantic version"; \
+		exit 1; \
+	fi
+	echo >&2 ">>>> v$(VERSION)"
+	git commit \
+		--allow-empty \
+		--gpg-sign="$(GPG_KEY)" \
+		--message "Release v$(VERSION)" \
+		--quiet \
+		--signoff
+	git tag \
+		--annotate \
+		--create-reflog \
+		--local-user "$(GPG_KEY)" \
+		--message "Version $(VERSION)" \
+		--sign \
+		"v$(VERSION)" master
+.PHONY: tag
 
 # A help target including self-documenting targets (see the awk statement)
+help: FORMAT="\033[36m%-30s\033[0m %s\n"
 help: ## This help target
-	@awk 'BEGIN {FS = ":.*?## "} /^[a-zA-Z_-]+:.*?## / \
-		{printf "\033[36m%-30s\033[0m  %s\n", $$1, $$2}' $(MAKEFILE_LIST)
+	awk 'BEGIN {FS = ":.*?## "} /^[%a-zA-Z_-]+:.*?## / \
+		{printf $(FORMAT), $$1, $$2}' $(MAKEFILE_LIST)
+	printf $(FORMAT) $(PROJECT)-%-% \
+		"Build for a specific OS and arch (where '%' = OS, arch)"
+.PHONY: help