implement review

Dockerfile

@@ -1,5 +1,5 @@
 # Build the manager binary
-FROM golang:1.21 as builder
+FROM --platform=${BUILDPLATFORM:-linux/amd64} golang:1.21 as builder
 
 ARG BUILDPLATFORM
 ARG TARGETPLATFORM

Makefile

@@ -165,13 +165,10 @@ docker-push: ## Push the operator docker image.
 PLATFORMS ?= linux/arm64,linux/amd64
 .PHONY: docker-buildx
 docker-buildx: ## Build and push docker image for the manager for cross-platform support
-	# copy existing Dockerfile and insert --platform=${BUILDPLATFORM} into Dockerfile.cross, and preserve the original Dockerfile
-	sed -e '1 s/\(^FROM\)/FROM --platform=\$$\{BUILDPLATFORM\}/; t' -e ' 1,// s//FROM --platform=\$$\{BUILDPLATFORM\}/' Dockerfile > Dockerfile.cross
-	- docker buildx create --name project-v3-builder
-	docker buildx use project-v3-builder
-	- docker buildx build --push --platform=$(PLATFORMS) --tag ${IMG} -f Dockerfile.cross .
-	- docker buildx rm project-v3-builder
-	rm Dockerfile.cross
+	- docker buildx create --name koperator-builder
+	docker buildx use koperator-builder
+	docker buildx build --push --platform=$(PLATFORMS) --tag ${IMG} -f Dockerfile .
+	- docker buildx rm koperator-builder
 
 bin/controller-gen: bin/controller-gen-$(CONTROLLER_GEN_VERSION) ## Symlink controller-gen-<version> into versionless controller-gen.
 	@ln -sf controller-gen-$(CONTROLLER_GEN_VERSION) bin/controller-gen