add make targets for building server images

hack/lib/golang.sh

@@ -40,6 +40,23 @@ IFS=" " read -ra KUBE_SERVER_TARGETS <<< "$(kube::golang::server_targets)"
 readonly KUBE_SERVER_TARGETS
 readonly KUBE_SERVER_BINARIES=("${KUBE_SERVER_TARGETS[@]##*/}")
 
+# The set of server targets we build docker images for
+kube::golang::server_image_targets() {
+  # NOTE: this contains cmd targets for kube::build::get_docker_wrapped_binaries
+  local targets=(
+    cmd/cloud-controller-manager
+    cmd/kube-apiserver
+    cmd/kube-controller-manager
+    cmd/kube-scheduler
+    cmd/kube-proxy
+  )
+  echo "${targets[@]}"
+}
+
+IFS=" " read -ra KUBE_SERVER_IMAGE_TARGETS <<< "$(kube::golang::server_image_targets)"
+readonly KUBE_SERVER_IMAGE_TARGETS
+readonly KUBE_SERVER_IMAGE_BINARIES=("${KUBE_SERVER_IMAGE_TARGETS[@]##*/}")
+
 # The set of server targets that we are only building for Kubernetes nodes
 # If you update this list, please also update build/BUILD.
 kube::golang::node_targets() {