Only copy new or modified files into VM on restart

pkg/minikube/assets/vm_assets.go

@@ -23,6 +23,7 @@ import (
 	"io"
 	"os"
 	"path"
+	"time"
 
 	"github.com/golang/glog"
 	"github.com/pkg/errors"
@@ -36,6 +37,7 @@ type CopyableFile interface {
 	GetTargetDir() string
 	GetTargetName() string
 	GetPermissions() string
+	GetModTime() time.Time
 }
 
 // BaseAsset is the base asset class
@@ -66,6 +68,11 @@ func (b *BaseAsset) GetPermissions() string {
 	return b.Permissions
 }
 
+// GetModTime returns mod time
+func (b *BaseAsset) GetModTime() time.Time {
+	return time.Time{}
+}
+
 // FileAsset is an asset using a file
 type FileAsset struct {
 	BaseAsset
@@ -104,6 +111,15 @@ func (f *FileAsset) GetLength() (flen int) {
 	return int(fi.Size())
 }
 
+// GetModTime returns modification time of the file
+func (f *FileAsset) GetModTime() time.Time {
+	fi, err := os.Stat(f.AssetName)
+	if err != nil {
+		return time.Time{}
+	}
+	return fi.ModTime()
+}
+
 func (f *FileAsset) Read(p []byte) (int, error) {
 	if f.reader == nil {
 		return 0, errors.New("Error attempting FileAsset.Read, FileAsset.reader uninitialized")

pkg/minikube/command/ssh_runner.go

@@ -23,6 +23,8 @@ import (
 	"io"
 	"os/exec"
 	"path"
+	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -143,6 +145,12 @@ func (s *SSHRunner) RunCmd(cmd *exec.Cmd) (*RunResult, error) {
 
 // Copy copies a file to the remote over SSH.
 func (s *SSHRunner) Copy(f assets.CopyableFile) error {
+	dst := path.Join(path.Join(f.GetTargetDir(), f.GetTargetName()))
+	if s.fileExistsInVM(f, dst) {
+		glog.Infof("Skipping copying %s as it already exists", f.GetAssetName())
+		return nil
+	}
+
 	sess, err := s.c.NewSession()
 	if err != nil {
 		return errors.Wrap(err, "NewSession")
@@ -156,7 +164,6 @@ func (s *SSHRunner) Copy(f assets.CopyableFile) error {
 	// StdinPipe is closed. But let's use errgroup to make it explicit.
 	var g errgroup.Group
 	var copied int64
-	dst := path.Join(path.Join(f.GetTargetDir(), f.GetTargetName()))
 	glog.Infof("Transferring %d bytes to %s", f.GetLength(), dst)
 
 	g.Go(func() error {
@@ -189,6 +196,49 @@ func (s *SSHRunner) Copy(f assets.CopyableFile) error {
 	return g.Wait()
 }
 
+func (s *SSHRunner) fileExistsInVM(f assets.CopyableFile, dst string) bool {
+	sess, err := s.c.NewSession()
+	if err != nil {
+		return false
+	}
+
+	// check if sizes of the two files are the same
+	srcSize := f.GetLength()
+	size := fmt.Sprintf("ls -l %s | cut -d \" \" -f5", dst)
+	out, err := sess.CombinedOutput(size)
+	if err != nil {
+		return false
+	}
+	dstSize, err := strconv.Atoi(strings.Trim(string(out), "\n"))
+	if err != nil {
+		return false
+	}
+	if srcSize != dstSize {
+		return false
+	}
+
+	sess, err = s.c.NewSession()
+	if err != nil {
+		return false
+	}
+	// ensure src file hasn't been modified since dst was copied over
+	srcModTime := f.GetModTime()
+	stat := "stat -c %Y" + fmt.Sprintf(" %s", dst)
+	out, err = sess.CombinedOutput(stat)
+	if err != nil {
+		return false
+	}
+	unix, err := strconv.Atoi(strings.Trim(string(out), "\n"))
+	if err != nil {
+		return false
+	}
+	dstModTime := time.Unix(int64(unix), 0)
+	if err != nil {
+		return false
+	}
+	return srcModTime.Before(dstModTime)
+}
+
 // teePrefix copies bytes from a reader to writer, logging each new line.
 func teePrefix(prefix string, r io.Reader, w io.Writer, logger func(format string, args ...interface{})) error {
 	scanner := bufio.NewScanner(r)