use make’s dependency handling to speed-up rebuilds

make allows us to run build targets based on dependencies and will only
execute targets if the dependencies have changed. This drastically
speeds up rebuilds if some targets have already been executed and
are still up to date.

Makefile

@@ -3,6 +3,16 @@ VERSION := $(shell git describe --tags --abbrev=0)
 BUILDSTR := ${VERSION} (\#${LAST_COMMIT} $(shell date -u +"%Y-%m-%dT%H:%M:%S%z"))
 
 YARN ?= yarn
+GOPATH ?= $(HOME)/go
+STUFFBIN ?= $(GOPATH)/bin/stuffbin
+FRONTEND_YARN_MODULES = frontend/node_modules
+FRONTEND_DIST = frontend/dist
+FRONTEND_DEPS = \
+	$(FRONTEND_YARN_MODULES) \
+	frontend/package.json \
+	frontend/vue.config.js \
+	frontend/babel.config.js \
+	$(shell find frontend/fontello frontend/public frontend/src -type f)
 
 BIN := listmonk
 STATIC := config.toml.sample \
@@ -13,26 +23,32 @@ STATIC := config.toml.sample \
 	frontend/dist/frontend:/frontend \
 	i18n:/i18n
 
-# Install dependencies for building.
-.PHONY: deps
-deps:
+.PHONY: build
+build: $(BIN)
+
+$(STUFFBIN):
 	go get -u github.com/knadh/stuffbin/...
+
+$(FRONTEND_YARN_MODULES): frontend/package.json frontend/yarn.lock
 	cd frontend && $(YARN) install
+	touch --no-create $(FRONTEND_YARN_MODULES)
 
 # Build the backend to ./listmonk.
-.PHONY: build
-build:
+$(BIN): $(shell find cmd -type f -name "*.go")
 	CGO_ENABLED=0 go build -o ${BIN} -ldflags="-s -w -X 'main.buildString=${BUILDSTR}' -X 'main.versionString=${VERSION}'" cmd/*.go
 
 # Run the backend.
 .PHONY: run
-run: build
+run: $(BIN)
 	./${BIN}
 
 # Build the JS frontend into frontend/dist.
-.PHONY: build-frontend
-build-frontend:
+$(FRONTEND_DIST): $(FRONTEND_DEPS)
 	export VUE_APP_VERSION="${VERSION}" && cd frontend && $(YARN) build
+	touch --no-create $(FRONTEND_DIST)
+
+.PHONY: build-frontend
+build-frontend: $(FRONTEND_DIST)
 
 # Run the JS frontend server in dev mode.
 .PHONY: run-frontend
@@ -47,14 +63,14 @@ test:
 # Bundle all static assets including the JS frontend into the ./listmonk binary
 # using stuffbin (installed with make deps).
 .PHONY: dist
-dist: build build-frontend
-	stuffbin -a stuff -in ${BIN} -out ${BIN} ${STATIC}
+dist: $(STUFFBIN) build build-frontend
+	$(STUFFBIN) -a stuff -in ${BIN} -out ${BIN} ${STATIC}
 
 # pack-releases runns stuffbin packing on the given binary. This is used
 # in the .goreleaser post-build hook.
 .PHONY: pack-bin
-pack-bin:
-	stuffbin -a stuff -in ${BIN} -out ${BIN} ${STATIC}
+pack-bin: $(STUFFBIN)
+	$(STUFFBIN) -a stuff -in ${BIN} -out ${BIN} ${STATIC}
 
 # Use goreleaser to do a dry run producing local builds.
 .PHONY: release-dry