Makefile: unconditionally build plugins

Changes the build targets of plugins to always unconditionally execute
without trying to check dependencies. The previous make targets were
faulty, e.g. changing something in the library didn't rebuild the
plugins. This is a simple and stupid fix that I believe is good enough -
building the plugins is really fast and go compiler caching makes it
super fast for "unnecessary" builds.

Signed-off-by: Markus Lehtonen <markus.lehtonen@intel.com>

Author: marquiz

Makefile

@@ -29,13 +29,14 @@ GO_LINT    := golint -set_exit_status
 GO_FMT     := gofmt
 GO_VET     := $(GO_CMD) vet
 
+GO_BUILD_FLAGS ?=
+
 GO_MODULES := $(shell $(GO_CMD) list ./...)
 
 GOLANG_CILINT := golangci-lint
 GINKGO        := ginkgo
 
-RESOLVED_PWD  := $(shell realpath $(shell pwd))
-BUILD_PATH    := $(RESOLVED_PWD)/build
+BUILD_PATH    := build
 BIN_PATH      := $(BUILD_PATH)/bin
 COVERAGE_PATH := $(BUILD_PATH)/coverage
 
@@ -69,6 +70,8 @@ allclean: clean clean-cache
 
 test: test-gopkgs
 
+FORCE:
+
 #
 # build targets
 #
@@ -98,14 +101,14 @@ clean-cache:
 # plugins build targets
 #
 
-$(BIN_PATH)/%: plugins/%/*
+$(BIN_PATH)/%: FORCE
 	$(Q)echo "Building $@..."; \
-	cd $(dir $<) && $(GO_BUILD) -o $@ .
+	$(GO_BUILD) -C plugins/$* -o ../../$@ $(GO_BUILD_FLAGS) .
 
-$(BIN_PATH)/wasm: plugins/wasm/
+$(BIN_PATH)/wasm: FORCE
 	$(Q)echo "Building $@..."; \
 	mkdir -p $(BIN_PATH) && \
-	cd $(dir $<) && GOOS=wasip1 GOARCH=wasm $(GO_BUILD) -o $@ -buildmode=c-shared .
+	GOOS=wasip1 GOARCH=wasm $(GO_BUILD) -C plugins/wasm -o ../../$@ $(GO_BUILD_FLAGS) -buildmode=c-shared .
 
 #
 # test targets

plugins/Dockerfile

@@ -27,8 +27,9 @@ RUN --mount=type=cache,target=/go/pkg/mod/ go mod download
 COPY . .
 
 RUN --mount=type=cache,target=/go/pkg/mod/ \
-    make /go/src/build/bin/${PLUGIN} \
-    GO_BUILD="CGO_ENABLED=0 go build -ldflags '-extldflags=-static'"
+    make build/bin/${PLUGIN} \
+    GO_BUILD="CGO_ENABLED=0 go build" \
+    GO_BUILD_FLAGS=" -ldflags '-extldflags=-static'"
 
 # Construct final image
 FROM scratch