Clarify logic around beginDownloadKicArtifacts

Author: tstromberg

pkg/minikube/node/cache.go

@@ -35,8 +35,8 @@ import (
 	"k8s.io/minikube/pkg/minikube/out"
 )
 
-// beginCacheRequiredImages caches images required for kubernetes version in the background
-func beginCacheRequiredImages(g *errgroup.Group, imageRepository string, k8sVersion string) {
+// beginCacheKubernetesImages caches images required for kubernetes version in the background
+func beginCacheKubernetesImages(g *errgroup.Group, imageRepository string, k8sVersion string) {
 	if !viper.GetBool("cache-images") {
 		return
 	}
@@ -82,17 +82,22 @@ func doCacheBinaries(k8sVersion string) error {
 	return machine.CacheBinariesForBootstrapper(k8sVersion, viper.GetString(cmdcfg.Bootstrapper))
 }
 
-func beginDownloadKicArtifacts(g *errgroup.Group, k8sVersion, cRuntime string) {
+// beginDownloadKicArtifacts downloads the kic image + preload tarball, returns true if preload is available
+func beginDownloadKicArtifacts(g *errgroup.Group, k8sVersion, cRuntime string) bool {
 	glog.Info("Beginning downloading kic artifacts")
 	g.Go(func() error {
 		glog.Infof("Downloading %s to local daemon", kic.BaseImage)
 		return image.WriteImageToDaemon(kic.BaseImage)
 	})
 
-	g.Go(func() error {
-		glog.Info("Caching tarball of preloaded images")
-		return download.Preload(k8sVersion, cRuntime)
-	})
+	if download.PreloadExists(k8sVersion, cRuntime) {
+		g.Go(func() error {
+			glog.Info("Caching tarball of preloaded images")
+			return download.Preload(k8sVersion, cRuntime)
+		})
+		return true
+	}
+	return false
 }
 
 func waitDownloadKicArtifacts(g *errgroup.Group) {

pkg/minikube/node/start.go

@@ -23,7 +23,6 @@ import (
 	"golang.org/x/sync/errgroup"
 	"k8s.io/minikube/pkg/addons"
 	"k8s.io/minikube/pkg/minikube/config"
-	"k8s.io/minikube/pkg/minikube/download"
 	"k8s.io/minikube/pkg/minikube/driver"
 	"k8s.io/minikube/pkg/minikube/exit"
 	"k8s.io/minikube/pkg/minikube/kubeconfig"
@@ -41,17 +40,17 @@ func Start(mc config.ClusterConfig, n config.Node, primary bool, existingAddons
 	// See if we can create a volume of preloaded images
 	// If not, pull images in the background while the VM boots.
 	var kicGroup errgroup.Group
-	downloadImages := true
+	needKubernetesImages := true
 	if driver.IsKIC(driverName) {
-		if download.PreloadExists(k8sVersion, mc.KubernetesConfig.ContainerRuntime) {
-			beginDownloadKicArtifacts(&kicGroup, k8sVersion, mc.KubernetesConfig.ContainerRuntime)
-			downloadImages = false
+		// If we can download a preload tarball, it isn't necessary to pull Kubernetes images
+		if beginDownloadKicArtifacts(&kicGroup, k8sVersion, mc.KubernetesConfig.ContainerRuntime) {
+			needKubernetesImages = false
 		}
 	}
 
 	var cacheGroup errgroup.Group
-	if downloadImages {
-		beginCacheRequiredImages(&cacheGroup, mc.KubernetesConfig.ImageRepository, k8sVersion)
+	if needKubernetesImages {
+		beginCacheKubernetesImages(&cacheGroup, mc.KubernetesConfig.ImageRepository, k8sVersion)
 	}
 
 	// Abstraction leakage alert: startHost requires the config to be saved, to satistfy pkg/provision/buildroot.