Extract preloaded tarball as soon as minikube volume is created

Extracting preload currently takes 6 seconds. This PR begins preload extraction as soon as the minikube volume is created, and runs it in parallell with creating the container node and setting up SSH.

This shaves 2-3 secnods off of `node.StartHost`

pkg/drivers/kic/kic.go

@@ -22,6 +22,7 @@ import (
 	"os/exec"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/docker/machine/libmachine/drivers"
@@ -112,6 +113,28 @@ func (d *Driver) Create() error {
 		}
 	}
 
+	if err := oci.SetupContainerNode(params); err != nil {
+		return errors.Wrap(err, "setting up container node")
+	}
+
+	var waitForPreload sync.WaitGroup
+	waitForPreload.Add(1)
+	go func() {
+		defer waitForPreload.Done()
+		// If preload doesn't exist, don't bother extracting tarball to volume
+		if !download.PreloadExists(d.NodeConfig.KubernetesVersion, d.NodeConfig.ContainerRuntime) {
+			return
+		}
+		t := time.Now()
+		glog.Infof("Starting extracting preloaded images to volume")
+		// Extract preloaded images to container
+		if err := oci.ExtractTarballToVolume(download.TarballPath(d.NodeConfig.KubernetesVersion, d.NodeConfig.ContainerRuntime), params.Name, BaseImage); err != nil {
+			glog.Infof("Unable to extract preloaded tarball to volume: %v", err)
+		} else {
+			glog.Infof("Took %f seconds to extract preloaded images to volume", time.Since(t).Seconds())
+		}
+	}()
+
 	if err := oci.CreateContainerNode(params); err != nil {
 		return errors.Wrap(err, "create kic node")
 	}
@@ -120,19 +143,7 @@ func (d *Driver) Create() error {
 		return errors.Wrap(err, "prepare kic ssh")
 	}
 
-	// If preload doesn't exist, don't bother extracting tarball to volume
-	if !download.PreloadExists(d.NodeConfig.KubernetesVersion, d.NodeConfig.ContainerRuntime) {
-		return nil
-	}
-	t := time.Now()
-	glog.Infof("Starting extracting preloaded images to volume")
-	// Extract preloaded images to container
-	if err := oci.ExtractTarballToVolume(download.TarballPath(d.NodeConfig.KubernetesVersion, d.NodeConfig.ContainerRuntime), params.Name, BaseImage); err != nil {
-		glog.Infof("Unable to extract preloaded tarball to volume: %v", err)
-	} else {
-		glog.Infof("Took %f seconds to extract preloaded images to volume", time.Since(t).Seconds())
-	}
-
+	waitForPreload.Wait()
 	return nil
 }
 

pkg/drivers/kic/oci/oci.go

@@ -84,6 +84,18 @@ func DeleteContainer(ociBin string, name string) error {
 	return nil
 }
 
+// SetupContainerNode sets up the container node
+func SetupContainerNode(p CreateParams) error {
+	if p.OCIBinary != Docker {
+		return nil
+	}
+	if err := createDockerVolume(p.Name, p.Name); err != nil {
+		return errors.Wrapf(err, "creating volume for %s container", p.Name)
+	}
+	glog.Infof("Successfully created a docker volume %s", p.Name)
+	return nil
+}
+
 // CreateContainerNode creates a new container node
 func CreateContainerNode(p CreateParams) error {
 	runArgs := []string{
@@ -122,10 +134,6 @@ func CreateContainerNode(p CreateParams) error {
 		runArgs = append(runArgs, "--volume", fmt.Sprintf("%s:/var:exec", hostVarVolPath))
 	}
 	if p.OCIBinary == Docker {
-		if err := createDockerVolume(p.Name, p.Name); err != nil {
-			return errors.Wrapf(err, "creating volume for %s container", p.Name)
-		}
-		glog.Infof("Successfully created a docker volume %s", p.Name)
 		runArgs = append(runArgs, "--volume", fmt.Sprintf("%s:/var", p.Name))
 		// setting resource limit in privileged mode is only supported by docker
 		// podman error: "Error: invalid configuration, cannot set resources with rootless containers not using cgroups v2 unified mode"