add Dockerfile and build target

Dockerfile

@@ -0,0 +1,11 @@
+FROM gcr.io/distroless/base-debian11 
+
+WORKDIR /
+
+COPY ./alertmanager ./alertmanager
+
+EXPOSE 8080
+
+USER nonroot:nonroot
+
+ENTRYPOINT ["./alertmanager"]

Makefile

@@ -1,8 +1,16 @@
-clean:
+ALERTMANAGER_VERSION := $(shell ./alertmanager --version | cut -d" " -f3)
+
+clean: 
 	rm alertmanager
 
-build:
-	go build
+build: vet
+	go build -tags netgo
+
+docker-build: build
+	 docker build -t alertmanager:$(ALERTMANAGER_VERSION) -f Dockerfile .     
 
 test:
-	go test ./... -v
+	go test ./... -v
+
+vet:
+	go vet ./...