build_image.go

// buildLocalImage build a docker image from the supplied `path` parameter.
// The image built is intended to be pushed to a local docker registry.
// This function assumes there is a Dockerfile in the dir
func buildLocalImage(path string) error {
  // get current working dir, to resolve the path to Dockerfile
  wd, err := os.Getwd()
  if err != nil {
     return err
  }

  // create a docker buildContext by `archiving` the files
  // the target dir
  buildCtx, err := createBuildContext(path)
  if err != nil {
     return err
  }

  // form a unique docker tag. the first string seg is the local docker registry host
  tag := fmt.Sprintf("%s%s%s", "docker-registry:5000/", build.Name(), p.md5()[:6])
  ctx := context.Background()
  // build image. reader can be used to get output from docker deamon
  reader, err := p.client.ImageBuild(ctx, buildCtx, types.ImageBuildOptions{
     Dockerfile: "Dockerfile", PullParent: true, Tags: []string{tag}, Remove: true, NoCache: true,
  })
  if err != nil {
     return err
  }

  for {
	buf := make([]byte, 512)
	_, err := reader.Body.Read(buf)
	if err != nil {
	   if err == io.EOF {
		break
	    }
	    log.Println("error reading response ", err)
	    continue
	}
	// print outputs
  	log.Println(string(buf[:]))
   }
  // yay! no errors
  return nil
}