postfix: improve building scenario

postfix/Makefile

@@ -1,13 +1,19 @@
-VERSION=3.5.9-1
+VERSION=3.5.9
+BUILD=2
 IMAGE=postfix
 REGISTRY=gitea.geekhome.org/ghp
 
+DOVECOT_VERSION=2.3.16
+POSTFIX_VERSION=$(VERSION)
+
 .PHONY: build push all
 
 build:
-	docker build -t $(REGISTRY)/$(IMAGE):$(VERSION) .
+	docker build --build-arg DOVECOT_VERSION=$(DOVECOT_VERSION) \
+    --build-arg POSTFIX_VERSION=$(POSTFIX_VERSION) \
+    -t $(REGISTRY)/$(IMAGE):$(VERSION)-$(BUILD) .
 
 push:
-	docker push $(REGISTRY)/$(IMAGE):$(VERSION)
+	docker push $(REGISTRY)/$(IMAGE):$(VERSION)-$(BUILD)
 
 all: build push