Use API also when pulling from helpers used in client

pkg/compiler/backend/simpleimg.go

@@ -16,7 +16,6 @@
 package backend
 
 import (
-	"os"
 	"os/exec"
 	"strings"
 
@@ -178,33 +177,6 @@ func (s *SimpleImg) ExportImage(opts Options) error {
 	return nil
 }
 
-// ExtractRootfs extracts the docker image content inside the destination
-func (s *SimpleImg) ExtractRootfs(opts Options, keepPerms bool) error {
-	name := opts.ImageName
-	path := opts.Destination
-
-	if !s.ImageExists(name) {
-		if err := s.DownloadImage(opts); err != nil {
-			return errors.Wrap(err, "failed pulling image "+name+" during extraction")
-		}
-	}
-
-	os.RemoveAll(path)
-
-	buildarg := []string{"unpack", "-o", path, name}
-	s.ctx.Debug(":tea: Extracting image " + name)
-
-	s.ctx.Spinner()
-	defer s.ctx.SpinnerStop()
-
-	out, err := exec.Command("img", buildarg...).CombinedOutput()
-	if err != nil {
-		return errors.Wrap(err, "Failed extracting image: "+string(out))
-	}
-	s.ctx.Debug(":tea: Image " + name + " extracted")
-	return nil
-}
-
 func (s *SimpleImg) Push(opts Options) error {
 	name := opts.ImageName
 	bus.Manager.Publish(bus.EventImagePrePush, opts)