allow kubectl to be built statically

* Package kubectl in a container
* Add example with a pod using kubectl as a sidecar

examples/kubectl-container/Makefile

@@ -0,0 +1,30 @@
+# Use:
+#
+# `make kubectl` will build kubectl.
+# `make tag` will suggest a tag.
+# `make container` will build a container-- you must supply a tag.
+# `make push` will push the container-- you must supply a tag.
+
+kubectl:
+	KUBE_STATIC_OVERRIDES="kubectl" ../../hack/build-go.sh cmd/kubectl; cp ../../_output/local/bin/linux/amd64/kubectl .
+
+.tag: kubectl
+	./kubectl version -c | grep -o 'GitVersion:"[^"]*"' | cut -f 2 -d '"' > .tag
+
+tag: .tag
+	@echo "Suggest using TAG=$(shell cat .tag)"
+	@echo "$$ make container TAG=$(shell cat .tag)"
+	@echo "or"
+	@echo "$$ make push TAG=$(shell cat .tag)"
+
+container:
+	$(if $(TAG),,$(error TAG is not defined. Use 'make tag' to see a suggestion))
+	docker build -t gcr.io/google_containers/kubectl:$(TAG) .
+
+push: container
+	$(if $(TAG),,$(error TAG is not defined. Use 'make tag' to see a suggestion))
+	gcloud preview docker push gcr.io/google_containers/kubectl:$(TAG)
+
+clean:
+	rm -f kubectl
+	rm -f .tag