read in dockerfile from stdin

Makefile

@@ -801,13 +801,13 @@ docker-build-kubeadm-control-plane: ## Build the docker image for kubeadm contro
 
 .PHONY: docker-build-docker-infrastructure
 docker-build-docker-infrastructure: ## Build the docker image for docker infrastructure controller manager
-	DOCKER_BUILDKIT=1 docker build --build-arg builder_image=$(GO_CONTAINER_IMAGE) --build-arg goproxy=$(GOPROXY) --build-arg ARCH=$(ARCH) --build-arg ldflags="$(LDFLAGS)" . -t $(CAPD_CONTROLLER_IMG)-$(ARCH):$(TAG) --file $(CAPD_DIR)/Dockerfile
+	cat $(CAPD_DIR)/Dockerfile | DOCKER_BUILDKIT=1 docker build --build-arg builder_image=$(GO_CONTAINER_IMAGE) --build-arg goproxy=$(GOPROXY) --build-arg ARCH=$(ARCH) --build-arg ldflags="$(LDFLAGS)" . -t $(CAPD_CONTROLLER_IMG)-$(ARCH):$(TAG) --file -
 	$(MAKE) set-manifest-image MANIFEST_IMG=$(CAPD_CONTROLLER_IMG)-$(ARCH) MANIFEST_TAG=$(TAG) TARGET_RESOURCE="$(CAPD_DIR)/config/default/manager_image_patch.yaml"
 	$(MAKE) set-manifest-pull-policy TARGET_RESOURCE="$(CAPD_DIR)/config/default/manager_pull_policy.yaml"
 
 .PHONY: docker-build-in-memory-infrastructure
 docker-build-in-memory-infrastructure: ## Build the docker image for in-memory infrastructure controller manager
-	DOCKER_BUILDKIT=1 docker build --build-arg builder_image=$(GO_CONTAINER_IMAGE) --build-arg goproxy=$(GOPROXY) --build-arg ARCH=$(ARCH) --build-arg ldflags="$(LDFLAGS)" . -t $(CAPIM_CONTROLLER_IMG)-$(ARCH):$(TAG) --file $(CAPIM_DIR)/Dockerfile
+	cat $(CAPIM_DIR)/Dockerfile | DOCKER_BUILDKIT=1 docker build --build-arg builder_image=$(GO_CONTAINER_IMAGE) --build-arg goproxy=$(GOPROXY) --build-arg ARCH=$(ARCH) --build-arg ldflags="$(LDFLAGS)" . -t $(CAPIM_CONTROLLER_IMG)-$(ARCH):$(TAG) -
 	$(MAKE) set-manifest-image MANIFEST_IMG=$(CAPIM_CONTROLLER_IMG)-$(ARCH) MANIFEST_TAG=$(TAG) TARGET_RESOURCE="$(CAPIM_DIR)/config/default/manager_image_patch.yaml"
 	$(MAKE) set-manifest-pull-policy TARGET_RESOURCE="$(CAPIM_DIR)/config/default/manager_pull_policy.yaml"
 
@@ -817,7 +817,7 @@ docker-build-clusterctl: ## Build the docker image for clusterctl
 
 .PHONY: docker-build-test-extension
 docker-build-test-extension: ## Build the docker image for core controller manager
-	DOCKER_BUILDKIT=1 docker build --build-arg builder_image=$(GO_CONTAINER_IMAGE) --build-arg goproxy=$(GOPROXY) --build-arg ARCH=$(ARCH) --build-arg ldflags="$(LDFLAGS)" . -t $(TEST_EXTENSION_IMG)-$(ARCH):$(TAG) --file ./test/extension/Dockerfile
+	cat ./test/extension/Dockerfile | DOCKER_BUILDKIT=1 docker build --build-arg builder_image=$(GO_CONTAINER_IMAGE) --build-arg goproxy=$(GOPROXY) --build-arg ARCH=$(ARCH) --build-arg ldflags="$(LDFLAGS)" . -t $(TEST_EXTENSION_IMG)-$(ARCH):$(TAG) --file -
 	$(MAKE) set-manifest-image MANIFEST_IMG=$(TEST_EXTENSION_IMG)-$(ARCH) MANIFEST_TAG=$(TAG) TARGET_RESOURCE="./test/extension/config/default/manager_image_patch.yaml"
 	$(MAKE) set-manifest-pull-policy TARGET_RESOURCE="./test/extension/config/default/manager_pull_policy.yaml"