fix: correct build context for dotnet8-builder Docker image (#427)

Author: davidchase

dotnet8/Makefile

@@ -11,5 +11,5 @@ dotnet8-env-img: Dockerfile
 	docker build --platform=$(PLATFORMS) -t $(REPO)/dotnet8-env:$(TAG) -f $< .
 
 dotnet8-builder-img: builder/Dockerfile
-	@echo === Building image $(REPO)/dotnet8-builder:$(TAG) using context $(CURDIR)/builder and dockerfile $<
-	docker build --platform=$(PLATFORMS) -t $(REPO)/dotnet8-builder:$(TAG) -f $< builder/
+	@echo === Building image $(REPO)/dotnet8-builder:$(TAG) using context $(CURDIR) and dockerfile $<
+	docker build --platform=$(PLATFORMS) -t $(REPO)/dotnet8-builder:$(TAG) -f $< .

dotnet8/builder/Makefile

@@ -5,4 +5,7 @@ PLATFORMS ?= linux/amd64,linux/arm64
 .PHONY: all
 all: dotnet8-builder-img
 
-dotnet8-builder-img: Dockerfile 
+# Override the rule to use parent directory as context
+dotnet8-builder-img: Dockerfile
+	@echo === Building image $(REPO)/dotnet8-builder:$(TAG) using parent directory as context
+	cd .. && docker buildx build --platform=$(PLATFORMS) -t $(REPO)/dotnet8-builder:$(TAG) $(DOCKER_FLAGS) -f builder/Dockerfile .