Cross-compile koperator for arm and intel. (#84)

Makefile

@@ -156,6 +156,20 @@ docker-build: ## Build the operator docker image.
 docker-push: ## Push the operator docker image.
 	docker push ${IMG}
 
+# PLATFORMS defines the target platforms for the manager image be built to provide support to multiple
+# architectures. (i.e. make docker-buildx IMG=myregistry/mypoperator:0.0.1). To use this option you need to:
+# - be able to use docker buildx. More info: https://docs.docker.com/build/buildx/
+# - have enabled BuildKit. More info: https://docs.docker.com/develop/develop-images/build_enhancements/
+# - be able to push the image to your registry (i.e. if you do not set a valid value via IMG=<myregistry/image:<tag>> then the export will fail)
+# To adequately provide solutions that are compatible with multiple platforms, you should consider using this option.
+PLATFORMS ?= linux/arm64,linux/amd64
+.PHONY: docker-buildx
+docker-buildx: ## Build and push docker image for the manager for cross-platform support
+	- 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