Address code review comments`

hack/metrics/metrics.go

@@ -19,6 +19,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -97,8 +98,20 @@ func execute() error {
 	}
 	defer sd.StopMetricsExporter()
 	ctx := context.Background()
+
+	// create a tmp file to download minikube to
+	tmp, err := ioutil.TempFile("", binary())
+	if err != nil {
+		return errors.Wrap(err, "creating tmp file")
+	}
+	if err := tmp.Close(); err != nil {
+		return errors.Wrap(err, "closing file")
+	}
+	defer os.Remove(tmp.Name())
+
+	// start loop where we will track minikube start time
 	for {
-		st, err := minikubeStartTime(ctx, projectID)
+		st, err := minikubeStartTime(ctx, projectID, tmp.Name())
 		if err != nil {
 			log.Printf("error collecting start time: %v", err)
 			continue
@@ -109,12 +122,10 @@ func execute() error {
 	}
 }
 
-func minikubeStartTime(ctx context.Context, projectID string) (float64, error) {
-	minikubePath, err := downloadMinikube()
-	if err != nil {
+func minikubeStartTime(ctx context.Context, projectID, minikubePath string) (float64, error) {
+	if err := downloadMinikube(ctx, minikubePath); err != nil {
 		return 0, errors.Wrap(err, "downloading minikube")
 	}
-	defer os.Remove(minikubePath)
 	defer deleteMinikube(ctx, minikubePath)
 
 	cmd := exec.CommandContext(ctx, minikubePath, "start", "--driver=docker", "-p", profile, "--memory=2000", "--trace=gcp")
@@ -123,11 +134,12 @@ func minikubeStartTime(ctx context.Context, projectID string) (float64, error) {
 	cmd.Stderr = os.Stderr
 
 	t := time.Now()
-	log.Print("Running minikube start....")
+	log.Printf("Running [%v]....", cmd.Args)
 	if err := cmd.Run(); err != nil {
 		return 0, errors.Wrapf(err, "running %v", cmd.Args)
 	}
-	return time.Since(t).Seconds(), nil
+	totalTime := time.Since(t).Seconds()
+	return totalTime, nil
 }
 
 func deleteMinikube(ctx context.Context, minikubePath string) {

hack/metrics/minikube.go

@@ -21,7 +21,9 @@ import (
 	"fmt"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"runtime"
+	"strings"
 
 	"log"
 
@@ -33,39 +35,62 @@ const (
 	bucketName = "minikube/latest"
 )
 
-// download minikube latest to a tmp file
-func downloadMinikube() (string, error) {
-	b := binary()
-	tmp, err := ioutil.TempFile("", b)
+// download minikube latest to file
+func downloadMinikube(ctx context.Context, minikubePath string) error {
+	client, err := storage.NewClient(ctx)
 	if err != nil {
-		return "", errors.Wrap(err, "creating tmp file")
+		return errors.Wrap(err, "creating client")
 	}
-	if err := tmp.Close(); err != nil {
-		return "", errors.Wrap(err, "closing tmp file")
+
+	if localMinikubeIsLatest(ctx, minikubePath, client) {
+		log.Print("local minikube is latest, skipping download...")
+		return nil
 	}
-	client, err := storage.NewClient(context.Background())
+
+	os.Remove(minikubePath)
+	// download minikube binary from GCS
+	obj := client.Bucket("minikube").Object(fmt.Sprintf("latest/%s", binary()))
+	rc, err := obj.NewReader(ctx)
 	if err != nil {
-		return "", errors.Wrap(err, "creating client")
-	}
-	ctx := context.Background()
-	rc, err := client.Bucket(bucketName).Object(b).NewReader(ctx)
-	if err != nil {
-		return "", errors.Wrap(err, "gcs new reader")
+		return errors.Wrap(err, "gcs new reader")
 	}
 	defer rc.Close()
 
 	data, err := ioutil.ReadAll(rc)
 	if err != nil {
-		return "", errors.Wrap(err, "ioutil read all")
+		return errors.Wrap(err, "ioutil read all")
 	}
-	log.Printf("downloading gs://%s/%s to %v", bucketName, b, tmp.Name())
-	if err := ioutil.WriteFile(tmp.Name(), data, 0777); err != nil {
-		return "", errors.Wrap(err, "writing file")
+	log.Printf("downloading gs://%s/%s to %v", bucketName, binary(), minikubePath)
+	if err := ioutil.WriteFile(minikubePath, data, 0777); err != nil {
+		return errors.Wrap(err, "writing minikubePath")
 	}
-	if err := os.Chmod(tmp.Name(), 0700); err != nil {
-		return "", errors.Wrap(err, "chmod")
+	if err := os.Chmod(minikubePath, 0700); err != nil {
+		return errors.Wrap(err, "chmod")
 	}
-	return tmp.Name(), nil
+	return nil
+}
+
+// localMinikubeIsLatest returns true if the local version of minikube
+// matches the latest version in GCS
+func localMinikubeIsLatest(ctx context.Context, minikubePath string, client *storage.Client) bool {
+	log.Print("checking if local minikube is latest...")
+	obj := client.Bucket("minikube").Object(fmt.Sprintf("latest/%s", binary()))
+	attrs, err := obj.Attrs(ctx)
+	if err != nil {
+		log.Printf("error getting %s object attrs: %v", obj.ObjectName(), err)
+		return false
+	}
+	gcsMinikubeVersion, ok := attrs.Metadata["commit"]
+	if !ok {
+		log.Printf("there is no commit: %v", attrs.Metadata)
+		return false
+	}
+	currentMinikubeVersion, err := exec.Command(minikubePath, "version", "--output=json").Output()
+	if err != nil {
+		log.Printf("error running [%s version]: %v", minikubePath, err)
+		return false
+	}
+	return strings.Contains(string(currentMinikubeVersion), gcsMinikubeVersion)
 }
 
 func binary() string {