chore: Use make target for protoc

Migrate the CI scripting of installing protoc to a Makefile target.

Signed-off-by: SuperQ <superq@gmail.com>

.github/workflows/ci.yml

@@ -43,15 +43,8 @@ jobs:
       - run: go test --tags=slicelabels -race ./cmd/prometheus ./model/textparse ./prompb/...
       - run: go test --tags=forcedirectio -race ./tsdb/
       - run: GOARCH=386 go test ./...
-      - run: |
-          VERSION="3.15.8"
-          env
-          set -x
-          curl -s -L https://github.com/protocolbuffers/protobuf/releases/download/v${VERSION}/protoc-${VERSION}-linux-x86_64.zip > /tmp/protoc.zip
-          unzip -d /tmp /tmp/protoc.zip
-          chmod +x /tmp/bin/protoc
-          export PATH=/tmp/bin:$PATH
-          make proto
+      - run: make protoc
+      - run: make proto
       - run: git diff --exit-code
 
   test_go_oldest:

Makefile

@@ -31,6 +31,15 @@ GOYACC_VERSION ?= v0.6.0
 
 include Makefile.common
 
+ifeq (arm, $(GOHOSTARCH))
+	PROTOC_ARCH ?= aarch_64
+else
+	PROTOC_ARCH ?= x86_64
+endif
+
+PROTOC_VERSION ?= 3.15.8
+PROTOC_URL     ?= https://github.com/protocolbuffers/protobuf/releases/download/v$(PROTOC_VERSION)/protoc-$(PROTOC_VERSION)-linux-$(PROTOC_ARCH).zip
+
 DOCKER_IMAGE_NAME       ?= prometheus
 
 # Only build UI if PREBUILT_ASSETS_STATIC_DIR is not set
@@ -129,6 +138,15 @@ assets-tarball: assets
 	@echo '>> packaging assets'
 	scripts/package_assets.sh
 
+.PHONY: protoc
+protoc:
+	@echo ">> Installing protoc"
+	$(eval PROTOC_TMP := $(shell mktemp))
+	curl -s -o $(PROTOC_TMP) -L $(PROTOC_URL) 
+	unzip -u $(PROTOC_TMP) bin/protoc -d $(FIRST_GOPATH)
+	chmod +x $(FIRST_GOPATH)/bin/protoc
+	rm -v $(PROTOC_TMP)
+
 .PHONY: parser
 parser:
 	@echo ">> running goyacc to generate the .go file."